VOLUME IV SLICE I Bisharin to Bohea (continued 8)

Serum-albumin gives all the typical colour and precipitation reactions of the albumins. If plasma be weakly acidified with sulphuric acid, then treated with crystals of ammonium sulphate until a slight precipitate forms, filtered and the filtrate allowed to evaporate very slowly, typical crystals of serum-albumin may form. According to many it is a uniform and specific substance, but others hold the view that it consists of at least three distinct substances, as shown by the fact that if a solution be gradually heated coagulation will occur at three different temperatures, viz. at 73°, 77° and 84° C. On the other hand the close agreement between different analyses of even the amorphous preparations points to there being but one serum-albumin.

When blood clots two new proteins make their appearance in the fluid part of the blood, or serum, as it is now called. The first of these is fibrin ferment (for its origin see section on Clotting below). The other, fibrinoglobulin, possesses all the typical characteristics of the globulins and coagulates at 64° C.

Carbohydrates.—Three several carbohydrates are described as occurring in plasma, viz. glycogen, animal gum and dextrose. If glycogen is present in solution in the plasma it is there in very small quantities only, and has probably arisen from the destruction of the white blood corpuscles, since some leucocytes undoubtedly contain glycogen. A small amount of carbohydrate having the formula for starch and yielding a reducing sugar on hydrolysis with acid has also been described. The constant carbohydrate constituent of plasma, however, is dextrose. This is present to the approximate amount of 0.15% in arterial blood. The amount may be much greater in the blood of the portal vein during carbohydrate absorption, and according to some observers there is less in venous than in arterial blood, but the difference is small and falls within the error of observation. The statement that when no absorption is taking place the blood of the hepatic vein is richer in dextrose than that of the portal vein (Bernard) is denied by Pavy.

Fats.—Plasma or serum is as a rule quite clear, but after a meal rich in fats it may become quite milky owing to the presence of neutral fats in a very fine state of subdivision. This suspended fat rapidly disappears from the blood after fat absorption has ceased. To some extent it varies in composition with that of the fat absorbed, but usually consists of the glycerides of the common fatty acids—palmitic, stearic and oleic. In addition, there is a small amount of fatty acid in solution in the plasma. As to the form in which this occurs there is some uncertainty. It is possibly present as a soap or even as a neutral fat, since a little can be dissolved in plasma, the solvent substance being probably protein or cholesterin. Fatty acids also appear to be present to some extent combined with cholesterin forming cholesterin esters (about 0.06%).

Other Organic Compounds.—In addition to the substances above described, belonging to the three main classes of food stuffs, there are still other organic bodies present in plasma in small amounts, which for convenience we may classify as non-nitrogenous and nitrogenous. Among the former may be mentioned lactic acid, glycerin, a lipochrome, and probably many other substances of a similar type whose separation has not yet been effected.

The non-protein nitrogenous constituents consist of the following: ammonia as carbonate or carbamate (0.2 to 0.6%), urea (0.02 to 0.05%), creatine, creatinine, uric acid, xanthine, hypoxanthine and occasionally hippuric acid. Three ferments are also described as being present: (1) a glycolytic ferment exerting an action upon dextrose; (2) a lipase or fat-splitting ferment; and (3) a diastase capable of converting starch into sugar.

Salts.—The saline constituents of plasma comprise chlorides, phosphates, carbonates and possibly sulphates, of sodium, potassium, calcium and magnesium. The most abundant metal is sodium and the most abundant acid is hydrochloric. These two are present in sufficient amount to form about 0.65% of sodium chloride. The phosphate is present to about 0.02%. Sulphuric acid is always present if the blood has been calcined for the purposes of the analysis, and may then be present to about 0.013%. This is, however, probably produced during the destruction of the protein, since it has been shown that no sulphate can be removed from normal plasma by dialysis. The amount of potassium present (0.03%) is less than one-tenth of that of the sodium, and the quantities of calcium and magnesium are even less.

Formed Elements.—When viewed under the microscope the main number of these are seen to be small yellow bodies of very uniform size, size and shape varying, however, in different animals. When observed in bulk they have a red colour, their presence in fact giving the typical colour to blood. These are the red blood corpuscles or erythrocytes (Gr. ἐρυθρός, red). Mingled with them in the blood are a smaller number of corpuscles which possess no colour and have therefore been called white blood corpuscles or leucocytes (Gr. λευκός, white). Lastly, there are present a large number of small lens-shaped structures, less in number than the red corpuscles, and much more difficult to distinguish. These are known as blood platelets.

Red Corpuscles.—These are present in very large numbers and, under normal conditions, all possess exactly the same appearance. With rare exceptions their shape is that of a biconcave disk with bevelled edges, the size varying somewhat in different animals, as is seen in the following table which gives their diameters:—

Man 0.0075 mm.

Dog 0.0073 mm.

Rabbit 0.0069 mm.

Cat 0.0065 mm.

Goat 0.0041 mm.

The coloured corpuscles of amphibia as well as of nearly all vertebrates below mammals are biconvex and elliptical. The following are the dimensions of some of the more common:—

Pigeon 0.0147 mm. long by 0.0065 mm. wide.

Frog 0.0223 ” ” 0.0157 ” ”

Newt 0.0293 ” ” 0.0195 ” ”

Proteus 0.0580 ” ” 0.0350 ” ”

Amphiuma 0.0770 ” ” 0.0460 ” ”

Their number also varies as follows:—

Man 4,000,000 to 5,000,000 per cub. mm.

Goat 9,000,000 to 10,000,000 ” ”

Sheep 13,000,000 to 14,000,000 ” ”

Birds 1,000,000 to 4,000,000 ” ”

Fish 250,000 to 2,000,000 ” ”

Frog 500,000 per cub. mm.

Proteus 36,000 ” ”

In mammals they are apparently homogeneous in structure, have no nucleus, but possess a thin envelope. Their specific gravity is distinctly higher than that of the plasma (1.088), so that if clotting has been prevented, blood on standing yields a large deposit which may form as much as half the total volume of the blood.

Chemical Composition.—On destruction the red corpuscles yield two chief proteins, haemoglobin and a nucleo-protein, and a number of other substances similar to those usually obtained on the break-down of any cellular tissue, such for instance as lecithin, cholesterin and inorganic salts. The most important protein is the haemoglobin. To it the corpuscle owes its distinctive property of acting as an oxygen carrier, for it possesses the power of combining chemically with oxygen and of yielding up that same oxygen whenever there is a decrease in the concentration of the oxygen in the solvent. Thus in a given solution of haemoglobin the amount of it which is combined with oxygen depends absolutely on the oxygen concentration. The greatest dissociation of oxyhaemoglobin occurs as the oxygen tension falls from about 40 to 20 mm. of mercury. That the oxygen forms a definite compound with the haemoglobin is proved by the fact that haemoglobin thoroughly saturated with oxygen (oxyhaemoglobin) has a definite absorption spectrum showing two bands between the D and E lines, whilst haemoglobin from which the oxygen has been completely removed only gives one band between those lines. In association with this, oxyhaemoglobin has a typical bright red colour, whereas haemoglobin is dark purple. A further striking characteristic of haemoglobin is that it contains iron in its molecule. The amount present, though small bears a perfectly definite quantitative relation to the amount of oxygen with which the haemoglobin is capable of combining (two atoms of oxygen to one of iron). One gram of haemoglobin crystals can combine with 1.34 cc. of oxygen. On destruction with an acid or alkali, haemoglobin yields a pigment portion, haematin, and a protein portion, globin, the latter belonging to the group of the histones (Gr. ἱστός, web, tissue). In this cleavage the iron is found in the pigment. By the use of a strong acid, it may be made to yield iron-free pigment, the remainder of the molecule being much further decomposed.

Destruction and Formation.—In the performance of their work the corpuscles gradually deteriorate. They are then destroyed, chiefly in the liver, but whether the whole of this process is effected by the liver alone is not decided. It is proved, however, that the destruction of the haemoglobin is entirely effected there. It was for a long time considered to be one of the functions of the spleen to examine the red corpuscles and to destroy or in some way to mark those no longer fitted for the performance of their work. It is proved that the destruction of the haemoglobin is entirely effected in the liver, since both the main cleavage products may be traced to this organ, which discharges the pigmentary portion as the bile pigment, but retains the iron-protein moiety at any rate for a time. The amount of bile pigment eliminated during the day indicates that the destruction must be considerable, and since the number of corpuscles does not vary there must be an equivalent formation of new ones. This takes place in the red bone-marrow, where special cells are provided for their continuous production. In embryonic life their formation is effected in another way. Certain mesodermic cells, resembling those of the connective tissue, collect masses of haemoglobin, and from these elaborate red blood corpuscles which thus come to lie in the fluid part of the cell. By a canalization of the branches of these cells which unite with branches of other cells the precursors of the blood capillaries are formed.

White Blood Corpuscles.—These constitute the second important group of formed elements in the blood, and number about 12,000 to 20,000 per cubic mm. They are typical wandering cells carried to all parts of the body by the blood stream, but often leave that stream and gain the tissue spaces by passing through the capillary wall. They exist in many varieties and were first classified according as, under the microscope, they presented a granular appearance or appeared clear. The cells were also distinguished from one another according as they possessed fine or coarse granules. The granules are confined to the protoplasm of the cell, and it has been shown that they differ chemically, because their staining properties vary. Thus, some granules select an acid stain, and the cells containing them are then designated acidophile or eosinophile;1 other granules select a basic stain and are called basophile, while yet others prefer a neutral stain (neutrophile).

In human blood the following varieties of leucocytes may be distinguished:—

1. The Polymorphonuclear Cell.—This possesses a nucleus of very complicated outline and a fair amount of protoplasm filled with numbers of fine granules which stain with eosin. They vary in size but are usually about 0.01 mm. in diameter. They are highly amoeboid and phagocytic, and form about 70% of the total number of leucocytes.

2. The Coarsely Granular Eosinophile Cell.—These large cells contain a number of well-defined granules which stain deeply with acid dyes. The nucleus is crescentic. The cells amount to about 2% of the total number of leucocytes, though the proportion varies considerably. They are actively amoeboid.

3. The Lymphocyte.—This is the smallest leucocyte, being only about 0.0065 mm. in diameter. It has a large spherical nucleus with a small rim of clear protoplasm surrounding it. It forms from 15 to 40% of the number of leucocytes, and is less markedly amoeboid than the other varieties.

4. The Hyaline (Gr. ὑάλινος, glassy, crystalline, ὔαλος, glass) cell or macrocyte (Gr. μακρός, long or large).—This is a cell similar to the last with a spherical, oval or indented nucleus, but it has much more protoplasm. It constitutes about 4% of all the leucocytes and is highly amoeboid and phagocytic.

5. The Basophile Cell.—This possesses a spherical nucleus and the protoplasm contains a small number of granules staining deeply with basic dyes. It is rarely found in the blood of adults except in certain diseases.

Functions.—These cells act as scavengers or as destroyers of living organisms that may have gained access to the tissue spaces. They play an important part in the chemical processes underlying the phenomena of immunity, and some at least are of importance in starting the process of clotting.

They are constantly suffering destruction in the performance of their work. Many, too, are lost to the body by their passage through the different mucous surfaces. Their origin is still obscure in many points. The lymphocytes are derived from lymphoid tissue, wherever it exists in the different parts of the body. The polymorphonuclear and eosinophile cells are derived from the bone-marrow, each by division of specific mother cells located in that tissue. The macrocyte is believed by many to represent a further stage in the development of the lymphocyte. Their rate of formation may be influenced by a variety of conditions—for instance, they are found to vary in number according to the diet and also, to a considerable extent, in disease.

Platelets.—The platelets or thrombocytes (Gr. θρόμβος, clot) are the third class of formed elements occurring in mammalian blood. There are still, however, many observers who consider that platelets are not present in the normal circulating blood, but only make their appearance after it has been shed or otherwise injured. They are minute lens-shaped structures, and may amount to as many as 800,000 per cubic mm. Under certain conditions, examination has shown that they are protoplasmic and amoeboid, and that each one contains a central body of different staining properties from the remainder of the structure. This has been regarded by some as a nucleus. On being brought into contact with a foreign surface they adhere to it firmly, very rapidly passing through a number of phases resulting ultimately in the formation of granular debris. In shed blood they tend to collect into groups, and during clotting, fibrin filaments may be observed to shoot out from these clumps.

Variations in the Blood of different Animals.—If we contrast the blood of different animals of the vertebrate class we find striking differences both in microscopic appearances and in chemical properties. In the first place, the corpuscles vary in amount and in kind. Thus, whilst in a mammal the corpuscles form 40 to 50% of the total volume of the blood, in the lower vertebrates the volume is much less, e.g. in frogs as low as 25% and in fishes even lower. The deficiency is chiefly in the red corpuscles, the ratio of white to red increasing as we examine the blood from animals lower in the scale. The corpuscles themselves are also found to vary, especially the red ones. In the mammal they are biconcave disks with bevelled edges, they do not contain a nucleus so that they are not cells. In the bird they are larger, ellipsoidal in shape and have a large nucleus in the centre of the cell. In reptiles and amphibia the red corpuscles are also nucleated, but the stroma portion containing the haemoglobin is arranged in a thickened annular part encircling the nucleus. When seen from the flat they are oval in section. In fishes the corpuscles show very much the same structure. A further very significant difference to be observed between the bloods of different vertebrates is in the amount of haemoglobin they contain; thus in the lower classes, fishes and amphibia, not only is the number of red corpuscles small but the amount of haemoglobin each corpuscle contains is relatively low. The concentration of the haemoglobin in the corpuscles attains its maximum in the mammal and the bird. Since the haemoglobin is practically the same from whatever animal it is obtained and can only combine with the same amount of oxygen, the oxygen-capacity of the blood of any vertebrate is in direct proportion to the amount of haemoglobin it contains. Therefore we see that as we ascend the scale in the vertebrate series the oxygen-carrying capacity of the blood rises. This increase was a natural preliminary condition for the progress of evolution. In order that a more active animal might be developed the main essential was that the chemical processes of the cell should be carried out more rapidly, and as these processes are fundamentally oxidative, increased activity entails an increased rate of supply of oxygen. This latter has been brought about in the animal kingdom in two ways, first by an increase in the concentration of the haemoglobin of the blood effected by an increase both in the number of corpuscles and in the amount of haemoglobin contained in each, and secondly by an increase in the rate at which the blood has been made to pass through the tissues. In the lower vertebrates the blood pressure is low and the haemoglobin content of the blood is low, consequently both rate of blood-flow and oxygen-content are low. In contrast with this, in higher vertebrates the blood pressure is high and the haemoglobin content of the blood is high, consequently both rate of blood-flow and oxygen-content are high. We must associate with this important step in evolution the means employed for the more rapid absorption of oxygen and for its increased rate of discharge to the tissues, the most important features of which are a diminution in the size of the corpuscle and the attainment of its peculiar shape, both resulting in the production of a relatively enormous corpuscular surface in a unit volume of blood.

Variations are also found in the white corpuscles as well as in the red, but these differences are not so striking and lie chiefly in unimportant details of structure of individual cells. Enormous variations are to be found in different species of mammals, but the cells generally conform to the types of secreting cells or phagocytes.

The platelets also differ in the different species. In the frog, for instance, many are spindle-shaped and contain a nucleus-like structure. Birds’ blood is stated to contain no platelets. The variations in number of these bodies have not been satisfactorily ascertained on account of the difficulties involved in any attempt to preserve them and to render them visible under the microscope.

Differences are also found in the chemical composition of the plasma. The chief variation is in the amount of protein present, which attains its maximum concentration in birds and mammals, while in reptiles, amphibia and fishes it is much less. The bloods of the latter two classes are much more watery than that of the mammal. Moreover, it has been proved that there are specific differences in the chemical nature of the various proteins present even between different varieties of mammals. Thus the ratio of the globulin fraction to the albumin fraction may vary considerably, and again, one or other of the proteins may be quite specific for the animal from which it is derived.

Clotting.—If a sample of blood be withdrawn from an animal, within a short time it undergoes a series of changes and becomes converted into a stiff jelly. It is said to clot. If the process is watched it is seen to start first from the surfaces where it is in contact with any foreign body; thence it extends through the blood until the whole mass sets solid. A short time elapses before this process commences—a time dependent upon two chief conditions, viz. the temperature at which the blood is kept and the extent of foreign surface with which it is brought into contact. Thus in a mammal the blood clots most quickly at a temperature a little above body temperature, while if the blood be cooled quickly the clotting is considerably delayed and in the case of some animals altogether prevented. For example, human blood kept at body temperature clots in three minutes, while if allowed to cool to room temperature the first sign of clotting may not make its appearance until eight minutes after its removal from the body. The process of clotting is also considerably accelerated by making the blood flow in a thin stream over a wide surface. The full completion of the process occupies some time if the blood be kept quiet, but ultimately the whole mass of the blood becomes converted into a solid. At this stage the containing vessel may be inverted without any drop of fluid escaping. A short time after this stage has been reached drops of a yellow fluid appear upon the surface and, increasing in size and number, run together to form a layer of fluid separated from the clot. This fluid is termed serum; its appearance is due to the contraction of the clot, which thus squeezes out the fluid from between its solid constituents. Contraction continues for about twenty-four hours, at the end of which time a large quantity (one-third or more of the total volume) of serum may have been separated. The clot contracts uniformly, thus preserving throughout the same general shape as that of the vessel in which the blood has been collected. Finally the clot swims freely in the serum which it has expressed.

The cause of the clot formation has been found to be the precipitation of a solid from the liquid plasma of the blood. This solid is in the form of very minute threads and hence is termed fibrin. The threads traverse the mass of blood in every possible direction, interlacing and thus confining in their meshes all the solid elements of the blood. Soon after their deposition they begin to contract, and as the meshwork they form is very minute they carry with them all the corpuscles of the blood. These with the fibrin form the shrunken clot.

If the rate at which blood clots be retarded either by cooling or by some other process the corpuscles may have time to settle, partially or completely, in which case distinct layers may form. The lowermost of these contains chiefly the red corpuscles, the second layer may be grey owing to the high percentage of leucocytes present, while a third, marked by opalescence only, may be very rich in platelets. Above these a clear layer of fluid may be found. This is plasma. The formation of these layers depends solely upon the rate of sedimentation of these elements, the rate depending partly upon differences in specific gravity, and partly upon the tendency the corpuscles have to run into clumps. Horse’s blood offers one of the best instances of the clumping of red corpuscles, and in this animal sedimentation of the red corpuscles is most rapid.

If now such a sedimented blood is allowed to clot the process is found to start in the middle two layers, i.e. in those containing the white corpuscles and platelets. From these layers it spreads through the rest of the liquid, being most retarded, however, in the red corpuscle layer, and particularly so if the sedimentation has been very complete. Not only does the clotting process start from the layers containing the leucocytes and platelets, but in them it also proceeds more quickly. These observations clearly indicate that the clotting process is initiated by some change starting from these elements.

The object of the clotting of the blood is quite clear. It is to prevent, as far as possible, any loss of blood when there is an injury to an animal’s vessels. The shed blood becomes converted into a solid, and this, extending into the interior of the ruptured vessel, forms a plug and thus arrests the bleeding. It is found that clotting is especially accelerated whenever the blood touches a foreign tissue, for instance, the outer layers of a torn blood-vessel wall, muscle tissue, &c., i.e. in exactly those conditions in which rapid clotting becomes of the greatest importance. Yet another very pregnant fact in connexion with clotting is that if an animal be bled rapidly and the blood collected in successive samples it is found that those collected last clot most quickly. Hence the more excessive the haemorrhage in any case, the greater becomes the onset of the natural cure for the bleeding, viz. clotting.

When we begin to inquire into the nature of clotting we have to determine in the first place whence the fibrin is derived. It has long been known that two chemical substances at least are requisite for its production. Thus certain fluids are known, e.g. some samples of hydrocele or pericardial fluid, which will not clot spontaneously, but will clot rapidly when a small quantity of serum or of an old blood-clot is added to it. The constituent substance which is present in the first-named fluids is known as fibrinogen, and that present in the serum or the clot is known as fibrin-ferment or thrombin.

Fibrinogen is present in living blood dissolved in the plasma; it is also present in such fluids as hydrocele or pericardial effusions, which, though capable of clotting, do not clot spontaneously. Thrombin, on the other hand, does not exist in living blood, but only makes its appearance there after blood is shed. It is not yet certain what is the nature of the final reaction between fibrinogen and thrombin. The possibilities are, that thrombin may act—(1) by acting upon fibrinogen, which it in some way converts into fibrin, (2) by uniting with fibrinogen to form fibrin, or (3) by yielding part of itself to the fibrinogen which thus becomes converted into fibrin. The experimental study of the rate of fibrin formation, when different strengths of thrombin solutions are allowed to act upon a fibrinogen solution, leads us to the probable conclusion that the first of these three possibilities is the correct one, and that thrombin therefore exerts a true ferment action upon fibrinogen. It is known that in the reaction, in addition to the formation of fibrin, yet another protein makes its appearance. This is known as fibrinoglobulin, and apparently it arises from the fibrinogen, so that the change would be one of cleavage into fibrin and fibrinoglobulin. It is very noteworthy that although the amount of fibrin formed during the clotting appears very bulky, yet the actual weight is extremely small, not more than 0.4 grms. from 100 cc. of blood.

Having ascertained that the clotting is due to the action of thrombin upon fibrinogen, we now see that the next step to be explained is the origin of thrombin. It has been shown that the final step in its formation consists in the combination of another substance, termed prothrombin, with calcium. Any soluble calcium salt is found to be effective in this respect, and conversely the removal of soluble calcium (e.g. by sodium oxalate) will prevent the formation of thrombin and therefore of clotting.

In the next place it can be proved that prothrombin does not exist as such in circulating blood, so that the problem becomes an inquiry as to the origin of prothrombin. Experiment has shown that in its turn prothrombin arises from yet another precursor, which is named thrombogen, and that thrombogen also is not to be found in circulating blood but only makes its appearance after the blood is shed. The conversion of thrombogen into prothrombin has been proved to be due to the action of a second ferment which has been named thrombokinase, and this latter is again absent from living blood. Hence the question arises, whence are derived thrombogen and thrombokinase? In the study of this question it has been found that if the blood of birds be collected direct from an artery through a perfectly clean cannula into a clean and dust-free glass vessel, it does not clot spontaneously. The plasma collected from such blood is found to contain thrombogen but no thrombokinase. A somewhat similar plasma may be prepared from a mammal’s blood by collecting samples of blood from an artery into vessels which have been thoroughly coated with paraffin, though in this instance thrombogen may be absent as well as thrombokinase. If plasma containing thrombogen but no thrombokinase be treated with a saline extract of any tissues it will soon clot. The saline extract contains thrombokinase. This ferment can therefore be derived from most tissues, including also the white blood corpuscles and the platelets. Thrombogen is produced from the leucocytes, but it is not yet certain whether it is also formed from the platelets. The discovery of the origin of the thrombokinase from tissue cells explains a fact that has long been known, namely, that if in collecting blood, it is allowed to flow over cut tissues, clotting is most markedly accelerated. The fact that birds’ blood if very carefully collected will not clot spontaneously tends to prove that thrombokinase is not derived from the leucocytes, and makes probable its origin from the platelets, for it is known that birds’ blood apparently does not contain platelets, at any rate in the form in which they are found in mammalian blood. When examining the general properties of platelets, attention was drawn to the remarkably rapid manner in which they undergo change on coming into contact with a foreign surface. It is apparently the actual contact which initiates these changes, changes which are fundamentally chemical in character, resulting in the production of thrombokinase and possibly also of thrombogen.

Thus as our knowledge at present stands the following statement gives a recapitulated account of the changes which constitute the many phases of clotting. When blood escapes from a blood-vessel it comes into contact with a foreign surface, either a tissue or the damaged walls of the cut vessel. Very speedily this contact results in the discharge of thrombogen and thrombokinase, the former from the white blood corpuscles and also possibly from the platelets, the latter from the platelets or from the tissue with which the blood comes in contact. The interaction of these two bodies next results in the formation of prothrombin, which, combining with the calcium of any soluble lime salt present, forms thrombin or fibrin-ferment. The last step in the change is the action of thrombin upon fibrinogen to form fibrin, and the clot is complete.

The intrinsic value to the animal of these changes is quite plain. The power of clotting and thus stopping haemorrhage is of essential importance, and yet this clotting must not occur within the living blood-vessels, or it would speedily result in death. That the tissues should be able to accelerate the process is of very obvious value. That the inner lining of the blood-vessels does not act as a foreign tissue is possibly due to the extreme smoothness of their surface.

Further, an animal must always be exposed to a possible danger in the absorption of some thrombin from a mass of clotted blood still retained within the body, and we know that if a quantity of active ferment be injected into the blood-stream intravascular clotting does result. Under all usual conditions this is obviated, the protective mechanism being of a twofold character. First, it is found that thrombin becomes converted very quickly into an inactive modification. Serum, for instance, very quickly loses its power of inducing clotting in fibrinogen solutions. Secondly, the body has been found to possess the power of making a substance, antithrombin, which can combine with thrombin forming a substance which is quite inactive as far as clotting is concerned. Finally, there is evidence that normal blood contains a small quantity of this substance, antithrombin, and that under certain conditions the amount present may be enormously increased.

(T. G. Br.)

Pathology of the Blood.

The changes in the blood in disease are probably as numerous and varied as the diseases which attack the body, for the blood is not only the medium of respiration, but also of nutrition, of defence against organisms and of many other functions, none of which can be affected without corresponding alterations occurring in the circulating fluid. The immense majority of these changes are, however, so subtle that they escape detection by our present methods. But in certain directions, notably in regard to the relations with micro-organisms, changes in the blood-plasma can be made out, though they are not associated in all cases with changes in the formed elements which float in it, nor with any obvious microscopical or chemical alterations.

The phenomena of immunity to the attacks of bacteria or their toxins, of agglutinative action, of opsonic action, of the precipitin tests, and of haemolysis, are all largely dependent on the inherent or acquired characters Immunity. of the blood serum. It is a commonplace that different people vary in their susceptibility to the attacks of different organisms, and different species of animals also vary greatly. This “natural immunity” is due partly to the power possessed by the leucocytes or white blood corpuscles of taking into their bodies and digesting or holding in an inert state organisms which reach the blood—phagocytosis,—partly to certain bodies in the blood serum which have a bactericidal action, or whose presence enables the phagocytes to deal more easily with the organisms. This natural immunity can be heightened when it exists, or an artificial immunity can be produced in various ways. Doses of organisms or their toxins can be injected on one or several occasions, and provided that the lethal dose be not reached, in most cases an increased power of resistance is produced. The organisms may be injected alive in a virulent condition, or with their virulence lessened by heat or cold, by antiseptics, by cultivation in the presence of oxygen, or by passage through other animals, or they may first be killed, or their toxins alone injected. The method chosen in each case depends on the organism dealt with. The result of this treatment is that in the animal treated protective substances appear in the serum, and these substances can be transferred to the serum of another animal or of man; in other words the active immunity of the experimental animal can be translated into the passive immunity of man. According to the nature of the substances injected into the former, its serum may be antitoxic, if it has been immunized against any particular toxin, or antibacterial, if against an organism. Familiar examples of these are, of the former diphtheria antitoxin, of the latter anti-plague and anti-typhoid sera. An antitoxin exerts its effects by actual combination with the respective toxin, the combination being inert. It is probable that the ultimate source of the antitoxin is to be found in the living cells of the tissues and that it passes from them into the blood. The action of an antibacterial serum depends on the presence in it of a substance known as “immune-body,” which has a special affinity and power of combining with the bacterium used. In order that it may exert this power it requires the presence of a substance normally present in the serum known as “complement.” The development of these “anti-bodies,” though it has been studied mainly in connexion with bacteria and their toxins, is not confined to their action, but can be demonstrated in regard to many other substances, such as ferments, tissue cells, red corpuscles, &c. In some animals, for example, the blood serum has the power of dissolving the red corpuscles of an animal of different species; e.g. the guinea-pig’s serum is “haemolytic” to the red corpuscles of the ox. This haemolytic power (haemolysis) can be increased by repeated injections of red corpuscles from the other animal, in this case also, as in the bacterial case, by the production and action of immune-body and complement. The antiserum produced in the case of the red corpuscles may sometimes, if injected into the first animal, whose red corpuscles were used, cause extensive destruction of its red corpuscles, with haemoglobinuria, and sometimes a fatal result.

Opsonic action depends on the presence of a substance, the “opsonin,” in the serum of an immunized animal, which makes the organism in question more easily taken up by the phagocytes (leucocytes) of the blood. The opsonin becomes fixed to the organisms. It is present to a certain extent in normal serum, but can be greatly increased by the process of immunization; and the “opsonic index,” or relation between the number of organisms taken up by leucocytes when treated with the serum of a healthy person or “control,” and with the serum of a person affected with any bacterial disease and under treatment by immunization, is regarded by some as representing the degree of immunity produced.

Agglutinative action is evidence of the presence in a serum of a somewhat similar set of substances, known as “agglutinins.” When a portion of an antiserum is added to an emulsion of the corresponding organism, the organisms, if they are motile, cease to move, and in any case become gathered together into clumps. In all probability several different bodies are concerned in this process. This reaction, in its practical applications at least, may be regarded as a reaction of infection rather than of immunization as ordinarily understood, for it is found that the blood serum of patients suffering from typhoid, Malta fever, cholera, and many other bacterial diseases, agglutinates the corresponding organisms. This fact has come to be of great importance in diagnosis.

The precipitin test depends on a somewhat analogous reaction. If the serum of an animal be injected repeatedly into another animal of different species, a “precipitin” appears in the serum of the animal treated, which causes a precipitate when added to the serum of the first animal. The special importance of this fact is that it can be utilized as a method of distinguishing between human blood and that of animals, which is often of importance in medical jurisprudence.

In this summary the facts adduced are practically all biological, and are due to the extraordinary activity with which the study of bacteriology (q.v.) has been pursued in recent years. The chemistry of the blood has not hitherto been found to give information of clinical or diagnostic importance, and nothing need here be added to what is said above on the physiology of the blood. Enough has been said, however, to show the extraordinary complexity of the apparently simple blood serum.

The methods at present employed in examining the blood clinically are: the enumeration of the red and white corpuscles per cubic millimetre; the estimation of the percentage of haemoglobin and of the specific gravity of the blood; the microscopic examination of freshly-drawn blood and of blood films made upon cover-glasses, fixed and stained. In special cases the alkalinity and the rapidity of coagulation may be ascertained, or the blood may be examined bacteriologically. We have no universally accepted means of estimating, during life, the total amount of blood in the body, though the method of J.S. Haldane and J. Lorrain Smith, in which the total oxygen capacity of the blood is estimated, and its total volume worked out from that datum, has seemed to promise important results (Journ. of Physiol. vol. xxv. p. 331, 1900). After death the amount of blood sometimes seems to be increased, and sometimes, as in “pernicious anaemia,” it is certainly diminished. But the high counts of red corpuscles which are occasionally reported as evidence of plethora or increase of the total blood are really only indications of concentration of the fluid except in certain rare cases. It is necessary, therefore, in examining blood diseases, to confine ourselves to the study of the blood-unit, which is always taken as the cubic millimetre, without reference to the number of units in the body.

Anaemia is often used as a generic term for all blood diseases, for in almost all of them the haemoglobin is diminished, either as a result of diminution in the number of the red corpuscles in which it is contained, or because the Anaemia. individual red corpuscles contain a smaller amount of haemoglobin than the normal. As haemoglobin is the medium of respiratory interchange, its diminution causes obvious symptoms, which are much more easily appreciated by the patient than those caused by alterations in the plasma or the leucocytes. It is customary to divide anaemias into “primary” and “secondary”: the primary are those for which no adequate cause has as yet been discovered; the secondary, those whose cause is known. Among the former are usually included chlorosis, pernicious anaemia, and sometimes the leucocythaemias; among the latter, the anaemias due to such agencies as malignant disease, malaria, chronic metallic poisoning, chronic haemorrhage, tubercle, Bright’s disease, infective processes, intestinal parasites, &c. As our knowledge advances, however, this distinction will probably be given up, for the causes of several of the primary anaemias have been discovered. For example, the anaemia due to bothriocephalus, an intestinal parasite, is clinically indistinguishable from the other forms of pernicious anaemia with which it used to be included, and leucocythaemia has been declared by Löwit, though probably erroneously, to be due to a blood parasite closely related to that of malaria. In all these conditions there is a considerable similarity in the symptoms produced and in the pathological anatomy. The general symptoms are pallor of the skin and mucous membranes, weakness and lassitude, shortness of breath, palpitation, a tendency to fainting, and usually also gastro-intestinal disturbance, headache and neuralgia. The heart is often dilated, and on auscultation the systolic murmurs associated with that condition are heard. In fatal cases the internal organs are found to be pale, and very often their cells contain an excessive amount of fat. In many anaemias there is a special tendency to haemorrhage. Most of the above symptoms and organic changes are directly due to diminished respiratory interchange from the loss of haemoglobin, and to its effect on the various organs involved. The diagnosis depends ultimately in all cases upon the examination of the blood.

Though the relative proportions of the leucocytes are probably continually undergoing change even in health, especially as the result of taking food, the number of red corpuscles remains much more constant. Through the agency of some unknown mechanism, the supply of fresh red corpuscles from the bone-marrow keeps pace with the destruction of effete corpuscles, and in health each corpuscle contains a definite and constant amount of haemoglobin. The disturbance of this arrangement in anaemia may be due to loss or to increased destruction of corpuscles, to the supply of a smaller number of new ones, to a diminution of the amount of haemoglobin in the individual new corpuscles, or to a combination of these causes. It is most easy to illustrate this by describing what happens after a haemorrhage. If this is small, the loss is replaced by the fully-formed corpuscles held in reserve in the marrow, and there is no disturbance. If it is larger, the amount of fluid lost is first made up by fluid drawn from the tissues, so that the number of corpuscles is apparently diminished by dilution of the blood; the erythroblasts, or formative red corpuscles, of the bone-marrow are stimulated to proliferation, and new corpuscles are quickly thrown into the circulation. These are apt, however, to be small and to contain a subnormal amount of haemoglobin, and it is only after some time that they are destroyed and their place taken by normal corpuscles. If the loss has been very great, nucleated red corpuscles may even be carried into the blood-stream. The blood possesses a great power of recovery, if time be given it, because the organ (bone-marrow) which forms so many of its elements never, in health, works at high pressure. Only a part of the marrow, the so-called red marrow, is normally occupied by erythroblastic tissue, the rest of the medullary cavity of the bones being taken up by fat. If any long-continued demand for red corpuscles is made, the fat is absorbed, and its place gradually taken by red marrow. This compensatory change is found in all chronic anaemias, no matter what their cause may be, except in some rare cases in which the marrow does not react.

It is often very difficult, especially in “secondary” anaemias, to say which of the above processes is mainly at work. In acute anaemias, such as those associated with septicaemia, there is no doubt that blood destruction plays the principal part. But if the cause of anaemia is a chronic one, a gastric cancer, for instance, though there may possibly be an increased amount of destruction of corpuscles in some cases, and though there is often loss by haemorrhage, the cancer interferes with nutrition, the blood is impoverished and does not nourish the erythroblasts in the marrow sufficiently, and the new corpuscles which are turned out are few and poor in haemoglobin. In chronic anaemias, regeneration always goes on side by side with destruction, and it is important to remember that the state of the blood in these conditions gives the measure, not of the amount of destruction which is taking place so much as of the amount of regeneration of which the organism is capable. The evidence of destruction has often to be sought for in other organs, or in secretions or excretions.

Of the so-called primary anaemias the most common is chlorosis, an anaemia which occurs only in the female sex, between the ages of fifteen and twenty-five as a rule. Its symptoms are those caused by a diminution of haemoglobin, and though it is never directly fatal, and is extremely amenable to treatment with iron preparations, its subjects very frequently suffer from relapses at varying intervals after the first attack. Its causation is probably complex. Bad hygienic conditions, over-fatigue, want of proper food, especially of the iron-containing proteids of meat, the strain put upon the blood and blood-forming organs by the accession of puberty and the occurrence of menstruation, all probably play a part in it. It has also been suggested that internal secretions may be concerned in stimulating the bone-marrow, and that in the female sex in particular the genital organs may act in this way. Imperfect assumption of function by these organs at puberty, caused perhaps by some of the above-mentioned conditions, might lead to sluggishness in the bone-marrow, and to the supply to the blood of the poorly-formed corpuscles deficient in haemoglobin which are characteristic of the disease. Chlorosis is the type of anaemias from imperfect blood-formation. Lorrain Smith has produced evidence to show that the total amount of haemoglobin in the body is not diminished in this disease, but that the blood-plasma is greatly increased in amount, so that the haemoglobin is diluted and the amount in each blood-unit greatly lessened.

Pernicious anaemia is a rarer disease than chlorosis, occurs usually later in life, and is distributed nearly equally between the two sexes. But it is of great importance because of its almost uniformly fatal termination, though its downward course is generally broken by temporary improvement on one or more occasions. The symptoms are those of a progressive anaemia, in which gastro-intestinal disturbance usually plays a large part, and nervous symptoms are common, and they become at last much more severe than those of any secondary anaemia. The patient may die in the first attack, but more usually, when things seem to be at their worst, improvement sets in, either spontaneously or as the result of treatment, and the patient slowly regains apparent health. This remission may be followed by a relapse, that again by a remission, and so on, but as a rule the disease is fatal within, at the outside, two or three years.

The prime cause of the disease is not known. It seems probable indeed that the causal factors are numerous. Severe malarial infection, syphilis, pregnancy, chronic gastro-intestinal disease, chronic gas-poisoning, are all, in different cases, known to have been causally associated with it, and it is probable that a congenital weakness of the bone-marrow has often to do with its production, as in many cases a family or hereditary history of the disease can be obtained. The condition is now regarded as a chronic toxaemia, partly because of the clinical symptoms and pathological appearances, partly because analogous conditions can be produced experimentally by such poisons as saponin and toluylendiamin, and partly because of the facts of bothriocephalus anaemia. The site of production of the toxin, or toxins, for it is possible that several may have the same effect on the blood, is possibly not always the same, but must often be the alimentary canal, as bothriocephalus anaemia proves. Not all persons affected with this intestinal tapeworm contract the disease, but only those in whose intestines the worm is dead and decomposing or sometimes only “sick.” The expulsion of the worm puts an end to the absorption of the toxin and the patients recover. No adequate explanation of the formation of the toxin in the immense majority of the cases, in which there is no tapeworm, has yet been given. It is certain that no organism as yet known is concerned.

This toxaemia affects the marrow and through it the blood, the gastro-intestinal apparatus and the nervous system, especially the spinal cord, in different proportions in different cases. The effect upon the marrow is to alter the type of red corpuscle formation, causing a reversion to the embryonic condition, in which the nucleated red corpuscles are large (megaloblasts), and the corpuscles in the blood formed from them are also large, are apparently ill suited to the needs of the adult, and easily break down, as the deposits of iron in the liver, spleen, kidneys and marrow prove. Whether this reversion is due to an exhaustion of the normal process or to an inhibition of it is not definitely known. The result is that the circulating red corpuscles are enormously diminished; it is usual to find 1,000,000 or less in the cubic millimetre instead of the normal 5,000,000. Though the haemoglobin is of course absolutely diminished, it is always, in severe cases, present in relatively higher percentage than the red corpuscles, because the average red corpuscle is larger and contains more haemoglobin than the normal. The large nucleated red corpuscles (megaloblasts) with which the marrow is crowded, often appear in the blood.

Other anaemias, such as those known as lymphadenoma, or Hodgkin’s disease, splenic anaemia, chloroma, leucanaemia and the anaemia pseudo-leucaemica of children, need not be described here, as they are either rare or their occurrence or nature is still too much under discussion.

The number and nature of the leucocytes in the blood bears no constant or necessary relation to the number or condition of the red corpuscles, and their variations depend on entirely different conditions. The number in the Leucocytosis. cubic millimetre is usually about 7000, but may vary in health from 5000 to 10,000. A diminution in their number is known as leucopenia, and is found in starvation, in some infective diseases, as for example in typhoid fever, in malaria and Malta fever, and in pernicious anaemia. An increase is very much more frequent, and is known as leucocytosis, though in this term is usually connoted a relative increase in the proportion of the polymorphonuclear neutrophile leucocytes. Leucocytosis occurs under a great variety of conditions, normally to a slight extent during digestion, during pregnancy, and after violent exercise, and abnormally after haemorrhage, in the course of inflammations and many infective diseases, in malignant disease, in such toxic states as uraemia, and after the ingestion of nuclein and other substances. It does not occur in some infective diseases, the most important of which are typhoid fever, malaria, influenza, measles and uncomplicated tuberculosis. In all cases where it is sufficiently severe and long continued, the reserve space in the bone-marrow is filled up by the active proliferation of the leucocytes normally found there, and is used as a nursery for the leucocytes required in the blood. In many cases leucocytosis is known to be associated with the defence of the organism from injurious influences, and its amount depends on the relation between the severity of the attack and the power of resistance. There may be an increase in the proportions present in the blood of lymphocytes (lymphocytosis), and of eosinophile cells (eosinophilia). This latter change is associated specially with some forms of asthma, with certain skin diseases, and with the presence of animal parasites in the body, such as ankylostoma and filaria.

The disease in which the number of leucocytes in the blood is greatest is leucocythaemia or leucaemia. There are two main forms of this disease, in both of which there are anaemia, enlargement of the spleen and lymphatic Leucaemia. glands, or of either of them, leucocytic hypertrophy of the bone-marrow, and deposits of leucocytes in the liver, kidney and other organs. The difference lies in the kind of leucocytes present in excess in the blood, blood-forming organs and deposits in the tissues. In the one form these are lymphocytes, which are found in health mainly in the marrow, the blood itself, the lymph glands and in the lymphatic tissue round the alimentary canal; in the other they are the kinds of leucocytes normally found in the bone-marrow-myelocytes, neutrophile, basophile and eosinophile, and polymorphonuclear cells, also neutrophile, basophile and eosinophile. The clinical course of the two forms may differ. The first, known as lymphatic leucaemia or lymphaemia, may be acute, and prove fatal in a few weeks or even days with rapidly advancing anaemia, or may be chronic and last for one or two years or longer. The second, known as spleno-myelogenous leucaemia or myelaemia, is almost always chronic, and may last for several years. Recovery does not take place, though remissions may occur. The use of the X-rays has been found to influence the course of this disease very favourably. The most recent view of the pathology of the disease is that it is due to an overgrowth of the bone-marrow leucocytes, analogous in some respects to tumour growth and caused by the removal of some controlling mechanism rather than by stimulation. The anaemia accompanying the disease is due partly to the leucocyte overgrowth, which takes up the space in the marrow belonging of right to red corpuscle formation and interferes with it.

(G. L. G.)

1 The suffix -phile, Greek φιλεῖν, to love, prefer, is in scientific terminology frequently applied to substances that exhibit such preference for particular stains or reagents, the names of which form the first part of the word.

BLOOD-LETTING. There are certain morbid conditions when a patient may obtain marked relief from the abstraction of a certain amount of blood, from three or four ounces up to twenty or even thirty in extreme cases. This may be effected by venesection, or the application of leeches, or more rarely by cupping (q.v.). Unfortunately, in years gone by, blood-letting was used to such excess, as a cure for almost every known disease, that public opinion is now extremely opposed to it. In certain pathological conditions, however, it brings relief and saves life when no other means would act with sufficient promptness to take its place.

Venesection, in which the blood is usually withdrawn from the median-basilic vein of the arm, has the disadvantage that it can only be performed by the medical man, and that the patient’s friends are generally very much opposed to the idea. But the public are not nearly so prejudiced against the use of leeches; and as the nurse in charge can be instructed to use these if occasion arises, this is the form of blood-letting usually practised to-day. From one to twelve leeches are applied at the time, the average leech withdrawing some two drachms of blood. Should this prove insufficient, as much again can be abstracted by the immediate application of hot fomentations to the wounds. They should always be applied over some bony prominence, that pressure may be effectively used to stop the haemorrhage afterwards. They should never be placed over superficial veins, or where there is much loose subcutaneous tissue. If, as is often the case, there is any difficulty in making them bite, the skin should be pricked at the desired spot with the point of a sterilized needle, and the leech will then attach itself without further trouble. Also they must be left to fall off of their own accord, the nurse never dragging them forcibly off. If cold and pressure fail to stop the subsequent haemorrhage, a little powdered alum or other styptic may be inserted in the wound. The following are the main indications for their use, though in some cases they are better replaced by venesection, (1) For stagnation of blood on the right side of the heart with constant dyspnoea, cyanosis, &c. In acute lung disease, the sudden obstruction to the passage of blood through the lungs throws such an increased strain on the right ventricle that it may dilate to the verge of paralysis; but by lessening the total volume of blood, the heart’s work is lightened for a time, and the danger at the moment tided over. This is a condition frequently met with in the early stages of acute pneumonia, pleurisy and bronchitis, when the obstruction is in the lungs, the heart being normal. But the same result is also met with as a result of failure of compensation with back pressure in certain forms of heart disease (q.v.). (2) To lower arterial tension. In the early stages of cerebral haemorrhage (before coma has supervened), when the heart is working vigorously and the tension of the pulse is high, a timely venesection may lead to arrest of the haemorrhage by lowering the blood pressure and so giving the blood in the ruptured vessel an opportunity to coagulate. (3) In various convulsive attacks, as in acute uraemia.

BLOOD-MONEY, colloquially, the reward for betraying a criminal to justice. More strictly it is used of the money-penalty paid in old days by a murderer to the kinsfolk of his victim. These fines completely protected the offender from the vengeance of the injured family. The system was common among the Scandinavian and Teutonic races previous to the introduction of Christianity, and a scale of payments, graduated according to the heinousness of the crime, was fixed by laws, which further settled who could exact the blood-money, and who were entitled to share it. Homicide was not the only crime thus expiable: blood-money could be exacted for all crimes of violence. Some acts, such as killing any one in a church or while asleep, or within the precincts of the royal palace, were “bot-less”; and the death penalty was inflicted. Such a criminal was outlawed, and his enemies could kill him wherever they found him.

BLOODSTONE, the popular name of the mineral heliotrope, which is a variety of dark green chalcedony or plasma, with bright red spots, splashes and streaks. The green colour is due to a chloritic mineral; the red to haematite. Some coarse kinds are opaque, resembling in this respect jasper, and some writers have sought to restrict the name “bloodstone” to green jasper, with red markings, thus making heliotrope a translucent and bloodstone an opaque stone, but, though convenient, such a distinction is not generally recognized. A good deal of bloodstone comes from India, where it occurs in the Deccan traps, and is cut and polished at Cambay. The stone is used for seals, knife-handles and various trivial ornaments. Bloodstone is not very widely distributed, but is found in the basaltic rocks of the Isle of Rum in the west of Scotland, and in a few other localities. Haematite (Gr. αἷμα, blood), or native peroxide of iron, is also sometimes called “bloodstone.”

BLOOM (from A.S. blôma, a flower), the blossom of flowering plants, or the powdery film on the skin of fresh-picked fruit; hence applied to the surface of newly-minted coins or to a cloudy appearance on the varnish of painting due to moisture; also, in metallurgy, a term used of the rough billets of iron and steel, which have undergone a preliminary hammering or rolling, and are ready for further working.

BLOOMER, AMELIA JENKS (1818-1894), American dress-reformer and women’s rights advocate, was born at Homer, New York, on the 27th of May 1818. After her marriage in 1840 she established a periodical called The Lily, which had some success. In 1849 she took up the idea—previously originated by Mrs Elizabeth Smith Miller—of a reform in woman’s dress, and the wearing of a short skirt, with loose trousers, gathered round the ankles. The name of “bloomers” gradually became popularly attached to any divided-skirt or knickerbocker dress for women. Until her death on the 30th of December 1894 Mrs Bloomer took a prominent part in the temperance campaign and in that for woman’s suffrage.

BLOOMFIELD, MAURICE (1855- ), American Sanskrit scholar, was born on the 23rd of February 1855, in Bielitz, Austrian Silesia. He went to the United States in 1867, and ten years later graduated from Furman University, Greenville, South Carolina. He then studied Sanskrit at Yale, under W.D. Whitney, and at Johns Hopkins, to which university he returned as associate professor in 1881 after a stay of two years in Berlin and Leipzig, and soon afterwards was promoted professor of Sanskrit and comparative philology. His papers in the American Journal of Philology number a few in comparative linguistics, such as those on assimilation and adaptation in congeneric classes of words, and many valuable “Contributions to the Interpretation of the Vedas,” and he is best known as a student of the Vedas. He translated, for Max-Müller’s Sacred Books of the East, the Hymns of the Atharva-Veda (1897); contributed to the Bühler-Kielhorn Grundriss der indo-arischen Philologie und Altertumskunde the section “The Atharva-Veda and the Gopatha Brahmana” (1899); was first to edit the Kauçika-Sutra (1890), and in 1907 published, in the Harvard Oriental series, A Vedic Concordance. In 1905 he published Cerberus, the Dog of Hades, a study in comparative mythology.

BLOOMFIELD, ROBERT (1766-1823), English poet, was born of humble parents at the village of Honington, Suffolk, on the 3rd of December 1766. He was apprenticed at the age of eleven to a farmer, but he was too small and frail for field labour, and four years later he came to London to work for a shoemaker. The poem that made his reputation, The Farmer’s Boy, was written in a garret in Bell Alley. The manuscript, declined by several publishers, fell into the hands of Capell Lofft, who arranged for its publication with woodcuts by Bewick in 1800. The success of the poem was remarkable, over 25,000 copies being sold in the next two years. His reputation was increased by the appearance of his Rural Tales (1802), News from the Farm (1804), Wild Flowers (1806) and The Banks of the Wye (1811). Influential friends attempted to provide for Bloomfield, but ill-health and possibly faults of temperament prevented the success of these efforts, and the poet died in poverty at Shefford, Bedfordshire, on the 19th of August 1823. His Remains in Poetry and Verse appeared in 1824.

BLOOMFIELD, a town of Essex county, New Jersey, U.S.A., about 12 m. W. of New York, and directly adjoining the city of Newark on the N. Pop. (1900) 9668, of whom 2267 were foreign-born; (1905, state census) 11,668; (1910), 15,070. Area, 5.42 sq. m. Bloomfield is served by the Erie, and the Delaware, Lackawanna & Western railways, and by several electric lines connecting with Newark, Montclair, Orange, East Orange and other neighbouring places. It is a residential suburb of Newark and New York, is the seat of a German theological school (Presbyterian, 1869) and has the Jarvie Memorial library (1902). There is a Central Green, and in 1908 land was acquired for another park. Among the town’s manufactures are silk and woollen goods, paper, electric elevators, electric lamps, rubber goods, safety pins, hats, cream separators, brushes and novelties. The value of the town’s factory products increased from $3,370,924 in 1900 to $4,645,483 in 1905, or 37.8%. First settled about 1670-1675 by the Dutch and by New Englanders from the Newark colony, Bloomfield was long a part of Newark, the principal settlement at first being known as Wardsesson. In 1796 it was named Bloomfield in honour of General Joseph Bloomfield (1753-1823), who served (1775-1778) in the War of American Independence, reaching the rank of major, was governor of New Jersey in 1801-1802 and 1803-1812, brigadier-general in the United States army during the War of 1812, and a Democratic representative in Congress from 1817 to 1821. The township of Bloomfield was incorporated in 1812. From it were subsequently set off Belleville (1839), Montclair (1868) and Glen Ridge (1895).

BLOOMINGTON, a city and the county-seat of McLean county, Illinois, U.S.A., in the central part of the state, about 125 m. S.W. of Chicago. Pop. (1890) 20,484; (1900) 23,286, of whom 3611 were foreign-born, there being a large German element; (1910 census) 25,768. The city is served by the Chicago & Alton, the Illinois Central, the Cleveland, Chicago, Cincinnati & St Louis, and the Lake Erie & Western railways, and by electric inter-urban lines. Bloomington is the seat of the Illinois Wesleyan University (Methodist Episcopal, co-educational, founded in 1850), which comprises a college of liberal arts, an academy, a college of law, a college of music and a school of oratory, and in 1907 had 1350 students. In the town of Normal (pop. in 1900, 3795), 2 m. north of Bloomington, are the Illinois State Normal University (opened at Bloomington in 1857 and removed to its present site in 1860), one of the first normal schools in the Middle West, and the state soldiers’ orphans’ home (1869). Bloomington has a public library, and Franklin and Miller parks; among its principal buildings are the court house, built of marble, and the Y.M.C.A. building. Among the manufacturing establishments are foundries and machine shops, including the large shops of the Chicago & Alton railway, slaughtering and meat-packing establishments, flour and grist mills, printing and publishing establishments, a caramel factory and lumber factories. The value of the city’s factory products increased from $3,011,899 in 1900 to $5,777,000 in 1905, or 91.8%. There are valuable coal mines in and near the city, and the city is situated in a fine farming region. Bloomington derives its name from Blooming Grove, a small forest which was crossed by the trails leading from the Galena lead mines to Southern Illinois, from Lake Michigan to St Louis, and from the Eastern to the far Western states. The first settlement was made in 1822, but the town was not formally founded until 1831, when it became the county-seat of McLean county. The first city charter was obtained in 1850, and in 1857 the public school system was established. In 1856 Bloomington was the meeting place of a state convention called by the Illinois editors who were opposed to the Kansas-Nebraska Bill (see DECATUR). This was the first convention of the Republican party in Illinois; among the delegates were Abraham Lincoln, Richard Yates, John M. Palmer and Owen Lovejoy. The city has been the residence of a number of prominent men, including David Davis (1815-1886), an associate justice of the United States Supreme Court in 1862-1877, a member of the United States Senate in 1877-1883, and president pro tempore of the Senate in 1881-1883; Governor John M. Hamilton (1847-1905), Governor Joseph W. Fifer (b. 1840); and Adlai Ewing Stevenson (b. 1835), a Democratic representative in Congress in 1875-1877 and 1879-1881, and vice-president of the United States in 1893-1897. Bloomington’s prosperity increased after 1867, when coal was first successfully mined in the vicinity.

In the Transactions of the Illinois State Historical Society for 1905 may be found a paper, “The Bloomington Convention of 1856 and Those Who Participated in it.”

BLOOMINGTON, a city and the county-seat of Monroe county, Indiana, U.S.A., about 45 m. S. by W. of Indianapolis. Pop. (1890) 4018; (1900) 6460, including 396 negroes; (1910) 8838. It is served by the Chicago, Indianapolis & Louisville and the Indianapolis Southern (Illinois Central) railways. Bloomington is the seat of the Indiana University (co-educational since 1868), established as a state seminary in 1820, and as Indiana College in 1828, and chartered as the State university in 1838; in 1907-1908 it had 80 instructors, 2051 students, and a library of 65,000 volumes; its school of law was established in 1842, suspended in 1877 and re-established in 1889; its school of medicine was established in 1903; but most of the medical course is given in Indianapolis; a graduate school was organized in 1904; and a summer school (or summer term of eleven weeks) was first held in 1905. Dr David Starr Jordan was the first president of the university in 1885-1891, when it was thoroughly reorganized and its curriculum put on the basis of major subjects and departments. The university’s biological station is on Winona Lake, Kosciusko county. Among the manufactures of Bloomington are furniture and wooden ware. There are valuable limestone quarries in the vicinity. The city was first settled about 1818.

BLOOMSBURG, a town and the county-seat of Columbia county, Pennsylvania, U.S.A., on Fishing Creek, 2 m. from its confluence with the Susquehanna, and about 40 m. S.W. of Wilkes-Barre. Pop. (1890) 4635; (1900) 6170 (213 foreign-born); (1910) 7413. It is served by the Delaware, Lackawanna & Western, the Philadelphia & Reading, and the Bloomsburg & Sullivan and the Susquehanna, Bloomsburg & Berwick railways (the last two only 30 m. and 39 m. long respectively); and is connected with Berwick, Catawissa and Danville by electric lines. The town is built on a bluff commanding extensive views. Among the manufactures of Bloomsburg are railway cars, carriages, silk and woollen goods, furniture, carpets, wire-drawing machines and gun carriages. Iron ore was formerly obtained from the neighbouring hills. The town is the seat of a state normal school, established as such in 1869. Bloomsburg was laid out as a town in 1802, became the county-seat in 1846, and was incorporated in 1870.

BLOUNT, CHARLES (1654-1693), English author, was born at Upper Holloway on the 27th of April 1654. His father, Sir Henry Blount (1602-1682), was the author of a Voyage to the Levant, describing his own travels. He gave his son a careful education, and is said to have helped him in his Anima Mundi; or An Historical Narration of the Opinions of the Antients concerning Man’s Soul after his Life, according to unenlightened Nature (1679), which gave great offence by the sceptical views expressed in it. It was suppressed by order of the bishop of London, and even burnt by some over-zealous official, but a re-issue was permitted. Blount was an admirer of Hobbes, and published his “Last Sayings” (1679), a pamphlet consisting of extracts from The Leviathan. Great is Diana of the Ephesians, or the Original of Idolatry, together with the Political Institution of the Gentiles’ Sacrifices (1680) attracted severe criticism on the ground that in deprecating the evils of priestcraft Blount was attacking Christianity itself. His best-known book, The Two First Books of Philostratus concerning the Life of Apollonius Tyaneus... (1680), is said to have been prohibited in 1693, chiefly on account of the notes, which are stated by Bayle (note, s.v. Apollonius) to have been taken mainly from a MS. of Lord Herbert of Cherbury. Blount contributed materially to the removal of the restrictions on the freedom of the press, with two pamphlets (1693) by “Philopatris,” mainly derived from Milton’s Areopagitica. He also laid a successful trap for the censor, Edmund Bohun. Under the name of “Junius Brutus” he wrote a pamphlet entitled “King William and Queen Mary Conquerors.” The title-page set forth the theory of the justice of title by conquest, which Blount knew to be agreeable to Bohun. It was duly licensed, but was ordered by the House of Commons to be burnt by the common hangman, as being diametrically opposed to the attitude of William’s government on the subject. These proceedings showed the futility of the censorship, and hastened its overthrow.

Blount had fallen in love with his deceased wife’s sister, and, in despair of overcoming her scruples as to the legality of such a marriage, shot himself in the head. He survived for some time, refusing help except from his sister-in-law. Alexander Pope asserted (Epilogue to the Satires, Note, i. 124) that he wounded himself in the arm, pretending to kill himself, and that the result was fatal contrary to his expectations. He died in August 1693.

Shortly before his death a collection of his pamphlets and private papers was printed with a preface by Charles Gildon, under the title of the Oracles of Reason. His Miscellaneous Works (1695) is a fuller edition by the same editor.

BLOUNT (or Blunt), EDWARD (b. 1565?), the printer, in conjunction with Isaac Jaggard, of Mr William Shakespeares Comedies, Histories and Tragedies. Published according to the true Originall Copies (1623), usually known as the first folio of Shakespeare. It was produced under the direction of John Heming (d. 1630) and Henry Condell (d. 1627), both of whom had been Shakespeare’s colleagues at the Globe theatre, but as Blount combined the functions of printer and editor on other occasions, it is fair to conjecture that he to some extent edited the first folio. The Stationers’ Register states that he was the son of Ralph Blount or Blunt, merchant tailor of London, and apprenticed himself in 1578 for ten years to William Ponsonby, a stationer. He became a freeman of the Stationers’ Company in 1588. Among the most important of his publications are Giovanni Florio’s Italian-English dictionary and his translation of Montaigne, Marlowe’s Hero and Leander, and the Sixe Court Comedies of John Lyly. He himself translated Ars Aulica, or the Courtier’s Arte (1607) from the Italian of Lorenzo Ducci, and Christian Policie (1632) from the Spanish of Juan de Santa Maria.

BLOUNT, THOMAS (1618-1679), English antiquarian, was the son of one Myles Blount, of Orleton in Herefordshire. He was born at Bordesley, Worcestershire. Few details of his life are known. It appears that he was called to the bar at the Inner Temple, but, being a zealous Roman Catholic, his religion interfered considerably with the practice of his profession. Retiring to his estate at Orleton, he devoted himself to the study of the law as an amateur, and also read widely in other branches of knowledge. He died at Orleton on the 26th of December 1679. His principal works are Glossographia; or, a dictionary interpreting the hard words of whatsoever language, now used in our refined English tongue (1656, reprinted in 1707), which went through several editions and remains most amusing and instructive reading; Nomolexicon: a law dictionary interpreting such difficult and, obscure words and terms as are found either in our common or statute, ancient or modern lawes (1670; third edition, with additions by W. Nelson, 1717); and Fragmenta Antiquitatis: Ancient Tenures of land, and jocular customs of some mannors (1679; enlarged by J. Beckwith and republished, with additions by H.M. Beckwith, in 1815; again revised and enlarged by W.C. Hazlitt, 1874). Blount’s Boscobel (1651), giving an account of Charles II.’s preservation after Worcester, with the addition of the king’s own account dictated to Pepys, has been edited with a bibliography by C.G. Thomas (1894).

BLOUNT, SIR THOMAS POPE (1649-1697), English author, eldest son of Sir Henry Blount and brother of Charles Blount (q.v.), was born at Upper Holloway on the 12th of September 1649. He succeeded to the estate of Tittenhanger on his mother’s death in 1678, and in the following year was created a baronet. He represented the borough of St Albans in the two last parliaments of Charles II. and was knight of the shire from the revolution till his death. He married Jane, daughter of Sir Henry Caesar, by whom he had five sons and nine daughters. He died at Tittenhanger on the 30th of June 1697. His Censura celebrorum authorum sive tractatus in quo varia virorum doctorum de clarissimis cujusque seculi scriptoribus judicia traduntur (1690) was originally compiled for Blount’s own use, and is a dictionary in chronological order of what various eminent writers have said about one another. This necessarily involved enormous labour in Blount’s time. It was published at Geneva in 1694 with all the quotations from modern languages translated into Latin, and again in 1710. His other works are A Natural History, containing many not common observations extracted out of the best modern writers (1693), De re poetica, or remarks upon Poetry, with Characters and Censures of the most considerable Poets.... (1694), and Essays on Several Occasions (1692). It is on this last work that his claims to be regarded as an original writer rest. The essays deal with the perversion of learning, a comparison between the ancients and the moderns (to the advantage of the latter), the education of children, and kindred topics. In the third edition (1697) he added an eighth essay, on religion, in which he deprecated the multiplication of ceremonies. He displays throughout a hatred of pedantry and convention, which makes his book still interesting.

See A. Kippis, Biographia Britannica (1780), vol. ii. For an account of Blount’s family see Robert Clutterbuck. History and Antiquities of the County of Hertford (1815), vol. i. pp. 207-212.

BLOUNT, WILLIAM (1749-1800), American politician, was born in Bertie county, North Carolina, on the 26th of March 1749. He was a member of the Continental Congress in 1783-1784 and again in 1786-1787, of the constitutional convention at Philadelphia in 1787, and of the state convention which ratified the Federal constitution for North Carolina in 1789. From 1790 until 1796 he was, by President Washington’s appointment, governor of the “Territory South of the Ohio River,” created out of land ceded to the national government by North Carolina in 1789. He was also during this period the superintendent of Indian affairs for this part of the country. In 1791 he laid out Knoxville (Tennessee) as the seat of government. He presided over the constitutional convention of Tennessee in 1796, and, on the state being admitted to the Union, became one of its first representatives in the United States Senate. In 1797 his connexion became known with a scheme, since called “Blount’s Conspiracy,” which provided for the co-operation of the American frontiersmen, assisted by Indians, and an English force, in the seizure on behalf of Great Britain of the Floridas and Louisiana, then owned by Spain, with which power England was then at war. As this scheme, if carried out, involved the corrupting of two officials of the United States, an Indian agent and an interpreter, a breach of the neutrality of the United States, and the breach of Article V. of the treaty of San Lorenzo el Real (signed on the 27th of October 1795) between the United States and Spain, by which each power agreed not to incite the Indians to attack the other, Blount was impeached by the House of Representatives on the 7th of July 1797, and on the following day was formally expelled from the Senate for “having been guilty of high misdemeanor, entirely inconsistent with his public trust and duty as a senator.” On the 29th of January 1798 articles of impeachment were adopted by the House of Representatives. On the 14th of January 1799, however, the Senate, sitting as a court of impeachment, decided that it had no jurisdiction, Blount not then being a member of the Senate, and, in the Senate’s opinion, not having been, even as a member, a civil officer of the United States, within the meaning of the constitution. The case is significant as being the first case of impeachment brought before the United States Senate. “In a legal point of view, all that the case decides is that a senator of the United States who has been expelled from his seat is not after such expulsion subject to impeachment” (Francis Wharton, State Trials). In effect, however, it also decided that a member of Congress was not in the meaning of the constitution a civil officer of the United States and therefore could not be impeached. The “conspiracy” was disavowed by the British government, which, however, seems to have secretly favoured it. Blount was enthusiastically supported by his constituents, and upon his return to Tennessee was made a member and the presiding officer of the state senate. He died at Knoxville on the 21st of March 1800.

For a defence of Blount, see General Marcus J. Wright’s Account of the Life and Services of William Blount (Washington, D.C., 1884).

BLOUSE, a word (taken from the French) used for any loosely fitting bodice belted at the waist. In France it meant originally the loose upper garment of linen or cotton, generally blue, worn by French workmen to preserve their clothing, and, by transference, the workman himself.

BLOW, JOHN (1648-1708), English musical composer, was born in 1648, probably at North Collingham in Nottinghamshire. He became a chorister of the chapel royal, and distinguished himself by his proficiency in music; he composed several anthems at an unusually early age, including Lord, Thou hast been our refuge; Lord, rebuke me not; and the so-called “club anthem,” I will always give thanks, the last in collaboration with Pelham Humphrey and William Turner, either in honour of a victory over the Dutch in 1665, or—more probably—simply to commemorate the friendly intercourse of the three choristers. To this time also belongs the composition of a two-part setting of Herrick’s Goe, perjur’d man, written at the request of Charles II. to imitate Carissimi’s Dite, o cieli. In 1669 Blow became organist of Westminster Abbey. In 1673 he was made a gentleman of the chapel royal, and in the September of this year he was married to Elizabeth Braddock, who died in childbirth ten years later. Blow, who by the year 1678 was a doctor of music, was named in 1685 one of the private musicians of James II. Between 1680 and 1687 he wrote the only stage composition by him of which any record survives, the Masque for the Entertainment of the King: Venus and Adonis. In this Mary Davies played the part of Venus, and her daughter by Charles II., Lady Mary Tudor, appeared as Cupid. In 1687 he became master of the choir of St Paul’s church; in 1695 he was elected organist of St Margaret’s, Westminster, and is said to have resumed his post as organist of Westminster Abbey, from which in 1680 he had retired or been dismissed to make way for Purcell. In 1699 he was appointed to the newly created post of composer to the chapel royal. Fourteen services and more than a hundred anthems by Blow are extant. In addition to his purely ecclesiastical music Blow wrote Great sir, the joy of all our hearts, an ode for New Year’s day 1681-1682; similar compositions for 1683, 1686, 1687, 1688, 1689, 1693 (?), 1694 and 1700; odes, &c., for the celebration of St Cecilia’s day for 1684, 1691, 1695 and 1700; for the coronation of James II. two anthems, Behold, O God, our Defender, and God spake sometimes in visions; some harpsichord pieces for the second part of Playford’s Musick’s Handmaid (1869); Epicedium for Queen Mary (1695); Ode on the Death of Purcell (1696). In 1700 he published his Amphion Anglicus, a collection of pieces of music for one, two, three and four voices, with a figured-bass accompaniment. A famous page in Burney’s History of Music is devoted to illustrations of “Dr Blow’s Crudities,” most of which only show the meritorious if immature efforts in expression characteristic of English music at the time, while some of them (where Burney says “Here we are lost”) are really excellent. Blow died on the 1st of October 1708 at his house in Broad Sanctuary, and was buried in the north aisle of Westminster Abbey.

BLOW-GUN, a weapon consisting of a long tube, through which, by blowing with the mouth, arrows or other missiles can be shot accurately to a considerable distance. Blow-guns are used both in warefare and the chase by the South American Indian tribes inhabiting the region between the Amazon and Orinoco rivers, and by the Dyaks of Borneo. In the 18th century they were also known to certain North American Indians, especially the Choctaws and Cherokees of the lower Mississippi. Captain Bossu, in his Travels through Louisiana (1756), says of the Choctaws: “They are very expert in shooting with an instrument made of reeds about 7 ft. long, into which they put a little arrow feathered with the wool of the thistle (wild cotton?).” The blow-guns of the South American Indians differ in style and workmanship. That of the Macusis of Guiana, called pucuna, is the most perfect. It is made of two tubes, the inner of which, called oorah, is a light reed ½ in. in diameter which often grows to a length of 15 ft. without a joint. This is enclosed, for protection and solidity, in an outer tube of a variety of palm (Iriartella setigera). The mouth-piece is made of a circlet of silk-grass, and the farther end is feruled with a kind of nut, forming a sight. A rear open sight is formed of two teeth of a small rodent. The length of the pucuna is about 11 ft. and its weight 1½ ℔ The arrows, which are from 12 to 18 in. long and very slender, are made of ribs of the cocorite palm-leaf. They are usually feathered with a tuft of wild cotton, but some have in place of the cotton a thin strip of bark curled into a cone, which, when the shooter blows into the pucuna, expands and completely fills the tube, thus avoiding windage. Another kind of arrow is furnished with fibres of bark fixed along the shaft, imparting a rotary motion to the missile, a primitive example of the theory of the rifle. The arrows used in Peru are only a few inches long and as thin as fine knitting-needles. All South American blow-gun arrows are steeped in poison. The natives shoot very accurately with the pucuna at distances up to 50 or 60 yds.

The blow-gun of the Borneo Dyaks, called sumpitan, is from 6 to 7 ft. long and made of ironwood. The bore, of ½ in., is made with a long pointed piece of iron. At the muzzle a small iron hook is affixed, to serve as a sight, as well as a spear-head like a bayonet and for the same purpose. The arrows used with the sumpitan are about 10 in. long, pointed with fish-teeth, and feathered with pith. They are also envenomed with poison.

Poisoned arrows are also used by the natives of the Philippine island of Mindanao, whose blow-pipes, from 3 to 4 ft. long and made of bamboo, are often richly ornamented and even jewelled.

The principle of the blow-gun is, of course, the same as that of the common “pea-shooter.”

See Sport with Rod and Gun in American Woods and Waters, by A.M. Mayer, vol. ii. (Edinburgh, 1884); Wanderings in South America, &c., by Charles Waterton (London, 1828); The Head Hunters of Borneo, by Carl Bock (London, 1881).

BLOWITZ, HENRI GEORGES STEPHAN ADOLPHE DE (1825-1903), Anglo-French journalist, was born, according to the account given in his memoirs, at his father’s chateau in Bohemia on the 28th of December 1825. At the age of fifteen he left home, and travelled over Europe for some years in company with a young professor of philology, acquiring a thorough knowledge of French, German and Italian and a mixed general education. The finances of his family becoming straitened, young Blowitz was on the point of starting to seek his fortune in America, when he became acquainted in Paris with M. de Falloux, minister of public instruction, who appointed him professor of foreign languages at the Tours Lycée, whence, after some years, he was transferred to the Marseilles Lycée. After marrying in 1859 he resigned his professorship, but remained at Marseilles, devoting himself to literature and politics. In 1869 information which he supplied to a legitimist newspaper at Marseilles with regard to the candidature of M. de Lesseps as deputy for that city led to a demand for his expulsion from France. He was, however, allowed to remain, but had to retire to the country. In 1870 his predictions of the approaching fall of the Empire caused the demand for his expulsion to be renewed. While his case was under discussion the battle of Sedan was fought, and Blowitz effectually ingratiated himself with the authorities by applying for naturalization as a French subject. Once naturalized, he returned to Marseilles, where he was fortunately able to render considerable service to Thiers, who subsequently employed him in collecting information at Versailles, and when this work was finished offered him the French consulship at Riga. Blowitz was on the point of accepting this post when Laurence Oliphant, then Paris correspondent of The Times, for which Blowitz had already done some occasional work, asked him to act as his regular assistant for a time, Frederick Hardman, the other Paris correspondent of The Times, being absent. Blowitz accepted the offer, and when, later on, Oliphant was succeeded by Hardman he remained as assistant correspondent. In 1873 Hardman died, and Blowitz became chief Paris correspondent to The Times. In this capacity he soon became famous in the world of journalism and diplomacy. In 1875 the duc de Decazcs, then French foreign minister, showed Blowitz a confidential despatch from the French ambassador in Berlin (in which the latter warned his government that Germany was contemplating an attack on France), and requested the correspondent to expose the German designs in The Times. The publication of the facts effectually aroused European public opinion, and any such intention was immediately thwarted. Blowitz’s most sensational journalistic feat was achieved in 1878, when his enterprise enabled The Times to publish the whole text of the treaty of Berlin at the actual moment that the treaty was being signed in Germany. In 1877 and again in 1888 Blowitz rendered considerable service to the French government by his exposure of internal designs upon the Republic. He died on the 18th of January 1903.

My Memoirs, by H.S. de Blowitz, was published in 1903.

BLOWPIPE, in the arts and chemistry, a tube for directing a jet of air into a fire or into the flame of a lamp or gas jet, for the purpose of producing a high temperature by accelerating the combustion. The blowpipe has been in common use from the earliest times for soldering metals and working glass, but its introduction into systematic chemical analysis is to be ascribed to A.F. Cronstedt, and not to Anton Swab, as has been maintained (see J. Landauer, Ber. 26, p. 898). The first work on this application of the blowpipe was by G. v. Engeström, and was published in 1770 as an appendix to a treatise on mineralogy. Its application has been variously improved at the hands of T.O. Bergman, J.G. Gahn, J.J. Berzelius, C.F. Plattner and others, but more especially by the two last-named chemists.

The simplest and oldest form of blowpipe is a conical brass tube, about 7 in. in length, curved at the small end into a right angle, and terminating in a small round orifice, which is applied to the flame, while the larger end is applied to the mouth. Where the blast has to be kept up for only a few seconds, this instrument is quite serviceable, but in longer chemical operations inconvenience arises from the condensation of moisture exhaled by the lungs in the tube. Hence most blowpipes are now made with a cavity for retaining the moisture. Cronstedt placed a bulb in the centre of his blowpipe. Dr Joseph Black’s instrument consists of a conical tube of tin plate, with a small brass tube, supporting the nozzle, inserted near the wider end, and a mouth-piece at the narrow end.

The sizes of orifice recommended by Plattner are 0.4 and 0.5 mm. A trumpet mouth-piece is recommended from the support it gives to the cheeks when inflated. The mode of blowing is peculiar, and requires some practice; an uninterrupted blast is kept up by the muscular action of the cheeks, while the ordinary respiration goes on through the nostrils.

If the flame of a candle or lamp be closely examined, it will be seen to consist of four parts—(a) a deep blue ring at the base, (b) a dark cone in the centre, (c) a luminous portion round this, and (d) an exterior pale blue envelope (see Flame). In blowpipe work only two of these four parts are made use of, viz. the pale envelope, for oxidation, and the luminous portion, for reduction. To obtain a good oxidizing flame, the blowpipe is held with its nozzle inserted in the edge of the flame close over the level of the wick, and blown into gently and evenly. A conical jet is thus produced, consisting of an inner cone, with an outer one commencing near its apex—the former, corresponding to (a) in the free flame, blue and well defined; the latter corresponding to (d), pale blue and vague. The heat is greatest just beyond the point of the inner cone, combustion being there most complete. Oxidation is better effected (if a very high temperature be not required) the farther the substance is from the apex of the inner cone, for the air has thus freer access. To obtain a good reducing flame (in which the combustible matter, very hot, but not yet burned, is disposed to take oxygen from any compound containing it), the nozzle, with smaller orifice, should just touch the flame at a point higher above the wick, and a somewhat weaker current of air should be blown. The flame then appears as a long, narrow, luminous cone, the end being enveloped by a dimly visible portion of flame corresponding to that which surrounds the free flame, while there is also a dark nucleus about the wick. The substance to be reduced is brought into the luminous portion, where the reducing power is strongest.

Various materials are used as supports for substances in the blowpipe flame; the principal are charcoal, platinum and glass or porcelain. Charcoal is valuable for its infusibility and low conductivity for heat (allowing substances to be strongly heated upon it), and for its powerful reducing properties; so that it is chiefly employed in testing the fusibility of minerals and in reduction. The best kind of charcoal is that of close-grained pine or alder; it is cut in short prisms, having a flat smooth surface at right angles to the rings of growth. In this a shallow hole is made for receiving the substance to be held in the flame. Gas-carbon is sometimes used, since it is more permanent in the flame than wood charcoal. Platinum is employed in oxidizing processes, and in the fusion of substances with fluxes; also in observing the colouring effect of substances on the blowpipe flame (which effect is apt to be somewhat masked by charcoal). Most commonly it is used in the form of wire, with a small bend or loop at the end.

The mouth blowpipe is unsuitable for the production of a large flame, and cannot be used for any lengthy operations; hence recourse must be made to types in which the air-blast is occasioned by mechanical means. The laboratory form in common use consists of a bellows worked by either hand or foot, and a special type of gas burner formed of two concentric tubes, one conveying the blast, the other the gas; the supply of air and gas being regulated by stopcocks. The hot blast blowpipe of T. Fletcher, in which the blast is heated by passing through a copper coil heated by a separate burner, is only of service when a pointed flame of a fairly high temperature is required. Blowpipes in which oxygen is used as the blast have been manufactured by Fletcher, Russell & Co., and have proved of great service in conducting fusions which require a temperature above that yielded by the air-blowpipe.