A CYCLOPÆDIA OF PRACTICAL RECEIPTS, &c. VOLUME II (continued 13)

4. Almond, CASTOR, LINSEED, NUT, OLIVE, RAPE, and some other vegetable oils, are readily bleached by either of the following processes:—

a. Exposure in glass bottles to the sun’s rays, on the leads or roofs of houses, or in any other suitable position, open to the south-east and south. This is the method employed by druggists and oilmen to whiten their castor and linseed oils. 14 to 21 days’ exposure to the sun in clear weather during summer is usually sufficient for castor oil when contained in 2 to 4-quart pale green glass bottles (preferably the former), and covered with white gallipots inverted over them. The oil is filtered before exposing it to the light, as, if only in a slight degree opaque, it does not bleach well. Almond and olive oil are, when thus treated, apt to acquire a slight sulphurous smell; but this may be removed by filtration through a little animal charcoal, or, still better, by washing the oil with hot water.

b. Another method employed to decolour these oils is to heat them in a wooden, tinned, or well-glazed earthen vessel along with some dry ‘filtering powder’ (1 to 2 lbs. per gall.), with agitation for some time, and lastly, to filter them in the usual manner through an oil-bag. In this way the West-end perfumers prepare their ‘WHITE ALMOND OIL’ (OLEUM AMYGDALÆ ALBUM), and their ‘WHITE OLIVE OIL’ (OLEUM OLIVÆ ALBUM). Formerly, freshly burnt animal charcoal was used for this purpose, and is still so employed by some houses.

5. Mr Bancroft refines OILS FOR MACHINERY AND LUBRICATING PURPOSES generally, by agitating them with a lye of caustic soda of the sp. gr. 1·2. A sufficient quantity is known to have been added when, after repose, a portion begins to settle down clear at the bottom. About 4% to 8% is commonly required for lard oil and olive oil. After 24 hours’ repose the clear supernatant oil is decanted from the soapy sediment, and filtered.

6. Not only the oils above referred to, but all other oils and fats, may be rendered perfectly colourless by the use of a little chromic acid; or, what is the same, by a mixture of a solution of bichromate of potassa and sufficient sulphuric, hydrochloric, or nitric acid, to seize on all the alkali, and thus liberate the chromic acid.

7. Palm oil and Cocoa-nut oil are generally

a. The ‘butyraceous oil’ is liquefied by heat in a wooden vessel, and 7% to 9% of good chloride of lime, previously made into a smooth cream with water, is added, and the whole assiduously stirred until the ingredients appear united; the mixture is then allowed to cool, and is next cut up into small lumps, which are exposed to a free current of air for 2, 3, or even 4 weeks; these are melted in a wooden vessel heated by high-pressure steam circulating through leaden pipes, or in a cast-iron boiler lined with lead, and an equal weight of oil of vitriol (diluted with about 20 times its weight of water) is poured in, and the whole gently boiled until the oil is discoloured and runs clear; the fire is then moderated, and the whole allowed to settle; lastly, the fire is removed, and the oil is left to cool very slowly.

b. The process with chromic acid has been already noticed, but is more fully explained below.

c. The oil, heated to the temperature of about 250° Fahr., is exposed to the action of high-pressure steam, which is continuously ‘blown’ through it for 10 or 12 hours, or even longer. The process is greatly facilitated by the introduction of some chromic acid.

8. Mr Watt’s methods of purifying fats and oils are very effective, more especially for those intended for illumination. They are as follows:—

a. (For FISH OILS.) Each ton is boiled for ¹⁄₂ an hour with caustic soda, ¹⁄₂ lb., previously made into a weak lye with water; or steam is blown through the mixture for a like period; oil of vitriol, ¹⁄₂ lb., diluted with 6 times its weight of water, is next added, the whole again boiled for 15 minutes, and allowed to settle for an hour or longer, when the clear oil is run off from the water and sediment into the bleaching tubs; here solution of bichromate of potash, 4 lbs., in oil of vitriol, 2 lbs., previously diluted with water, q. s., together with a little nitric acid and some oxalic acid, are added, and after thorough admixture of the whole, by blowing steam through it, strong nitric acid, 1 lb., diluted with water, 1 quart, is poured in, and the boiling continued for ¹⁄₂ an hour longer; a small quantity of naphtha or rectified spirit of turpentine is then mixed in, and the oil is, finally, well washed with hot water, and left to settle.

b. (For PALM OIL.) The oil is melted by the heat of steam, and, after it has settled and cooled down to about 130° Fahr., is carefully decanted from the water and sediment into the steaming tubs; here a mixture of a saturated solution of bichromate of potash, 25 lbs., and oil of vitriol, 8 or 9 lbs., is added, and after thorough admixture, hydrochloric acid, 50 lbs., is poured in; the whole is then constantly stirred until it acquires a uniform greenish colour, or is sufficiently decoloured, a little more of the bleaching materials being added if the latter is not the case, after which it is allowed to repose for half an hour to settle; it is next run into a wooden vat, where it is washed, &c., as before.

c. (For VEGETABLE OILS.) These are treated with a solution of chromic acid, or with a solution of bichromate of potassa, or some mineral acid, as noticed at No. 6. For COLZA, LINSEED, MUSTARD, NUT, and RAPE OIL, a little hydrochloric acid is added; but for ALMOND, CASTOR, OLIVE OIL, and POPPY OIL, no such addition (at least in excess) is required.

9. Rancid oils and FATS are recovered by boiling them for about 15 minutes with a little water and calcined magnesia; or, by filtering them through freshly burnt charcoal.

In reference to the above processes, it may be useful to remark, that chlorine, the common bleacher and deodoriser of other substances, cannot be well employed directly in the purification of oils, as certain chemical reactions occur when these substances are brought together, which increase the colour instead of removing it, and are often otherwise injurious. The same remarks apply to the use of the ‘chlorides,’ which frequently fails in unskilful hands, and is, indeed, of questionable utility, except, perhaps, in the case of palm oil. Even charcoal exerts little of its usual energy on the oils, and whilst it removes or lessens their offensive odour, sometimes increases their colour. The addition of 1% or 2% of very pure and recently rectified naphtha or oil of turpentine (camphine) to lamp oil is a real improvement, since it increases its combustibility and its illuminative power.

Oils for medical purposes, as CASTOR OIL, COD-LIVER OIL &c., must not be subjected to any process beyond mere clarification by subsidence, filtration through Canton flannel or porous paper, or, at the utmost, washing with warm water, as otherwise their active and valuable properties, if not wholly removed, will be considerably lessened. See Filtration.

Purity. The fixed oils vary greatly in their value, and hence the constant inducement which leads the unprincipled dealer to adulterate the more expensive ones with those of a similar character, but of an inferior kind of grade. Various methods are adopted to detect these frauds, among which the following are the most valuable of those capable of general application. Others referring to individual oils will be found under the respective heads.

1. (From the odour.) The method of applying this test is to heat a few drops of the oil under examination in a small porcelain, platinum, or silver spoon or capsule (a watch-glass answers well), and to carefully compare the odour evolved with that arising from a known pure sample of the same kind andLINSEED, NUT, RAPE, SEAL, TRAIN, or WHALE OIL, is thus readily detected, and the imperfections of the sample, even if pure, rendered much more perceptible.

2. (From the density.)—a. According to M. Penot, every oil supposed to come from the same plant, or the same animal, has its own particular density, which, at the same temperature, never deviates more than a few thousandths. To apply this test, the relative density or specific gravity of the sample must be determined. This may be done by means of a thousand-grain bottle or an ordinary ‘AREOMETER,’ or, more conveniently, by an ‘ELAÏOMETER’ or ‘OLEOMETER,’ constructed and graduated for the purpose. ‘Fischer’s ELAÏOMETER’ or ‘OIL-BALANCE’ is much employed on the Continent for this purpose, and is a very useful instrument. On the large scale, the weight of an accurately measured imperial gallon of the oil may be taken.

b. M. Lauret, an eminent Parisian chemist, a short time since observed that the variations of the density of an oil from adulteration are rendered much more apparent when it is examined in a heated state. To render this discovery practically available, he plunges an ‘elaïometer,’ graduated for the given temperature, into a small tin cylinder nearly filled with the oil, and then places this in a vessel containing boiling water; as soon as the whole has acquired a uniform temperature, he observes the point on the scale of the instrument at which it floats. This point for—

Colza oil is 0°

Fish oil 83°

Poppy oil 124°

Hemp-seed oil 136°

Linseed oil 210°

c. By employing a specific gravity bottle or small glass globe, fitted with a stopper in which is hermetically fixed a capillary tube of about 8 or 9 inches in length, we may apply the above principle of M. Lauret with the greatest accuracy. This little apparatus is filled with the oil, and then immersed in boiling water for a sufficient length of time for it to acquire that temperature; it is then removed and weighed. The smallest adulteration is, it is said, in this way immediately detected.

When the density of the given sample has been taken, and the name of the oil used to adulterate it is known, the quantity of the latter present may be approximately determined from the specific gravities by the common method of alligation.[49]

3. (Sulphuric-acid test.)—a. Heidenreich was the first person who gave a useful and general application to the reactions which occur when oil of vitriol is mixed with the fatty oils. As soon as these substances are placed together, very intense chemical action commences, the temperature of the mixture rises, and the mass becomes coloured. These changes are sufficiently varied in the case of the different oils to furnish us with the means of identifying many of them, and of determining their purity. The method of M. Heidenreich is to lay a plate of white glass over a sheet of white paper; on the glass he places 10 or 15 drops of oil, and then adds to it a small drop of concentrated sulphuric acid (‘oil of vitriol’). The appearances which follow differ with the character of the fatty oil examined, and whether the acid is allowed to act on the oil undisturbed (without stirring) or the two are stirred together with a glass rod. In many cases, as with tallow oil, a peculiar odour as well as a change of colour is developed, and a further means of detection supplied. M. Heidenreich has minutely described these reactions, which, for the most part, closely resemble those given in the table, p. 1129. It is necessary, however, in order to ensure great accuracy, to compare the effect of the reagent on the sample with those which it produces on pure oil of the same kind and character under precisely similar circumstances.

b. M. Penot, who has followed up the researches of M. Heidenreich with considerable success, recommends the employment of 20 drops of oil, instead of only 10 or 15; and the use of a small capsule of white porcelain, instead of a plate of glass. He also employs a saturated solution of bichromate of potash in sulphuric acid, which he uses in the same proportion as before; but in this case the oil and the reagent are always stirred together.

The observations of M. Penot have been repeated in many cases by Mr Cooley, and the results, with additions, and rearranged, are given in the table, p. 1129.

“By perusing this table,” writes M. Penot, “it will be observed that the same oil does not, under all circumstances, yield precisely similar results with the same reagent. This depends on the place of growth, the age, and the manner of pressing. If, however, any oil be examined comparatively with a perfectly pure one, the proof of adulteration may be rendered, if not certain, at least probable, by noting the difference. Thus I obtained, by adding 1 part of either whale-train, or linseed oil, or oleic acid, or 10 parts of rapeseed oil, the following results:

Name of Oil. Reagents.

Sulphuric Acid. Solution of Bichromate of Potash.

Not stirred. Stirred. Stirred.

Rape oil with whale-train oil More red ground than with rape oil Brownish-olive coloured Small reddish lumps on a grey ground.

Rape oil with linseed oil No perceptible difference from the rape oil Olive coloured Small and more numerous red lumps on a very dark-green ground.

Rape oil with olein or oleic acid No perceptible difference from the rape oil Greenish brown Small brownish lumps on an olive-coloured ground.

“The adulteration being ascertained as far as is possible, the oil is then tested by endeavouring to discover the adulterating oil, either by reagents or by its odour when gently heated, as before described. This having been found out, small quantities of the suspected oil are added to a perfectly pure oil of the kind under examination. Every mixture is then tested by the reagents, until precisely similar results are obtained as those yielded by the oil under examination. Thus, the proportions of the two mixed oils will be discovered by approximation.” (M. Penot.) A simpler method of finding the proportions of the so mixed oils is referred to above.

4. (From increase of temperature.) M. Maumené proposed the increase of temperature arising from the admixture of monohydrated sulphuric acid (oil of vitriol, sp. gr. 1·845) with the fatty oils as a test of their purity, but a sufficient number of observations have not yet been made to furnish data for a general application of this method. According to MM. Faisst and Knauss, who have re-examined the subject, the following are the results when 15 grammes of oil are mixed with 5 grammes of the acid:

Rise of Temperature.

Almond oil 72·5°

Olive oil 68·0°

Poppy oil 127·0°

Rape or colza oil 100·0°

Linseed oil (with Nordhausen or fuming acid only) 133·0°

The above method is less liable to error when a larger quantity of the substances are thrown together.

5. The presence of FISH OIL in the vegetable oils may be readily detected by passing a stream of chlorine through them; the pure vegetable oils are not materially altered, but a mixture of the two turns dark brown or black.

6. Mr Coleman states that the presence of mineral oils in animal or vegetable oils can be easily detected by two characteristic tests—(1) the fluorescent properties they impart to all animal or vegetable oils. (2) The strongly marked aromatic burning flavour they communicate to mixtures containing them. The first-mentioned property is brought out by smearing a metallic surface, such as tin plate or steel, with the oil, and then viewing it at different angles in the open air or sunlight. Mr Coleman suggests that, in examining a dark-coloured oil, it may first be necessary to refine the sample by successive treatments with concentrated sulphuric acid and weak soda solution or lime water, so small a quantity as 2¹⁄₂ per cent. may then be detected by the bluish colour noticed on viewing the oil at certain angles and by tasting it.

The absence of resin oil must also be proved. Nitric acid is said to be a good test, as the colour developed is much greater than in pure oils. Sometimes it may be detected by the smell. The presence of 10 per cent. of resin or mineral oil in non-drying oils delays their solidification with the nitrate of mercury test.[50]

7. Miss Kate Crane[51] states that the cohesion figures of oils may be usefully employed as tests of the identity and purity of the oils. She says, “A number of experiments on this subject have led her to the conclusion that a little patient practice will teach the eye of the observer in a short time to detect the characteristic differences of the figures. To make these perfect it is necessary to observe the time in forming, for at different periods some varieties form figures very like; but with this precaution each is entirely characteristic.

“It is essential that the dish used, &c., be perfectly clean, so that when filled with water no dust or lint floats upon the surface, as this materially interferes with the perfect formation of the figure.

“A single drop is let fall from a burette or glass rod held steadily above the water, upon the centre of the surface. The experiments made with fixed oils are as follows:—Poppy-seed oil spreads instantly to a large figure, retaining an entire outline, and for a few seconds the surface is unbroken, except the bare intimation of a beaded edge.

“In a few moments little holes appear round the edge, and soon the whole surface is broken in like manner; these increase in size very slowly. In fifteen minutes the edge begins to open, forming indentations, which gradually work their way across the figure. As they increase in length these begin to curve, and in three quarters of an hour have doubled themselves two or three times.

“Cod-liver oil spreads in a large film; a little way from the edge a row of small holes appears, and in a minute or two the surface is covered with them; these gradually enlarge, assuming irregular shapes, soon separated by branching lines.

“Cod-liver oil with lard oil spreads very like the former, but in a few moments the edge

“Castor oil spreads instantly, the edge remaining entire; openings appear quickly in thirty seconds, and increase gradually, but unevenly, those nearer the edge being larger, and lengthening out irregularly as they spread. The figure lasts some time.

“Castor with a little lard oil makes a smaller figure, and not nearly so much broken; in five minutes the holes open into each other, and the figure breaks up from the edge.

“A mixture of castor and poppy-seed oils spreads to form a lacework border, but smooths out to an entire edge soon, and within a few seconds openings appear. The figure, in size and general appearance, is more like castor oil alone, but the holes spread less uniformly in a given time, a few being larger, but the greater portion much smaller. In fifteen minutes there is a general tendency to break up.

“Castor with a little croton oil throws out a spray, which in a few moments unites into a thin film. The spray, as it spreads, draws out the inner portion into radiate points, which open into a beautiful network, the centre cohering closely.

“Croton oil throws out, in spreading, a fine spray in advance of the more closely cohering portion, which follows quickly. The outer edge breaks up unevenly into little indentations, the border of the inside portion being quite broken, but gradually becomes nearly entire. The surface, too, has openings, which increase quite rapidly in size, the outer ones being much the larger. In the final breaking up, before the holes open one into another, the outlines are beautifully fringed.

8. “Spontaneous combustion ensues when a handful of cotton waste is embued with oil and placed in an air bath at 130° to 200° F. Boiled linseed oil required 1¹⁄₄ hour; raw linseed oil, 4 hours; lard oil, 4 hours; refined rape about 9 hours.”[52]

Mr Gellatly found that an admixture of 20 per cent. of mineral oil retarded combustion, and 50 per cent. prevented it completely.

M. Burstyn,[53] believing that the value of a fatty oil as a lubricant depends on the amount of acid it contains, has invented a method for volumetrically determining the acidity. The process is as follows:—A tall cylindrical vessel, provided with a ground-glass stopper, and having two marks on it to indicate respectively 100 cubic centimètres, and 200 cubic centimètres, is filled to the first mark with the oil to be tested, and to the second mark with 88 to 90 per cent. alcohol. The cylinder is then closed and well shaken. Equal quantities other than 100 cubic centimètres can be employed without any other change in the process. After standing two or three hours the oil settles, and the clear alcohol, which contains in solution the free acids and a little of the oil, rises to the top perfectly clear; 25 cubic centimètres of the clear alcohol is taken from the top by means of a pipette. A few drops of alcohol extract of turmeric is added, and the acid determined by means of a standard solution of potash, as in acetometry. The change from yellow to brownish red takes place with great sharpness when neutralisation is reached.

The number of cubic centimètres of potash employed, multiplied by four, gives the quantity of normal solution requisite to neutralise the free acid in 100 cubic centimètres of oil. As it is not an individual acid, but a variable mixture of acids, it is not possible to calculate the percentage of acids present. These numbers, however, may be taken as degrees of acidity. For instance, an oil of 3° of acidity is one which contains enough free acid to neutralise 3 cubic centimètres of normal alkali.

If we assume that oleic acid predominates, which in most cases is the fact, 1° of acidity correspond to 0·28 per cent. by weight of oleic acid. The olive oil of commerce has an acidity ranging from 0·4° to 12°. The first passes as very fine, and is called free from acid or salad oil, while the latter is known by smell and taste as very rancid. Oil that has 4° to 6° of acidity has been found to answer very well as a lubricator.

What relation there exists between the degree of acidity and any injurious effect upon metals is shown by the following experiments:—Four shallow vessels of sheet brass, having a surface of 40 square centimètres each, at the bottom, were filled to the depth of 2 millimètres, with oils of different acidity, and exposed to the air at the ordinary temperature. The vessels were soon more or less covered with green fatty salts, and the oil too acquired a green colour. Oil and vessel No. 1 were the only ones in which no change could be perceived. At the end of 3 days the vessels were cleaned with ether and weighed. The following table shows the amounts of action:

Vessel No. 1, filled with oil of 0·8° lost 0·03 gr.

” No. 2, ” 4·6° ” 0·22 ”

” No. 3, ” 7·8° ” 0·36 ”

” No. 4, ” 8·8° ” 0·04 ”

The quantity of metal destroyed, in equal times and under equal conditions, increases with the acidity of the oil.

The table on page 1128, by Mr Bottome, describes the most striking physical properties of some of the principal fixed oils.

⁂ The following are the principal fixed oils met with in commerce, or which are objects of interest or utility:

Oil of Al′monds. Syn. Oleum amygdalæ (B. P., Ph. L), O. amygdalarum (Ph. D.), O. amygdali communis (Ph. E.), L. “The oil expressed from the kernels.” (Ph. L.) “Bruise the fresh almonds in a stone mortar, then put them into a hempen sack, and express the oil, without heat.” (Ph. E.) The oil of almonds B. P. and of commerce is obtained from either the bitter or sweet almond, but chiefly from the first, on account of their less value, and the marc being employed in the manufacture of essential oil.

Prop., &c. Oil of almonds is black, demulcent, emollient, and nutritious; possesses a purely oleaginous taste, and is one of the most agreeable of the fixed oils; when taken in quantity it is mildly laxative; it is little affected by cold, and congeals with difficulty; is soluble in 35 parts of cold and 6 parts of boiling alcohol; ether dissolves it freely. Sp. gr. ·915 to ·918. Av. prod. Sweet almonds, 46%; bitter a., 41%.

Pur. It is extensively adulterated with poppy, nut, and teel oil, and not unfrequently with refined rape or colza oil. (See above.)

Oil of Bay. 1. (Expressed o. of b.; Oleum lauri, O. laurinum, L.) By expression from either fresh or dried bayberries, as castor oil. Limpid; insipid.

2. (By decoction; Butter of b.; Oleum lauri nobilis, O. l. verum, L.) From the berries, by boiling them in water, and skimming off the oil. Green, buttery; chiefly imported from Italy. Used by the vulgar in bruises, sprains, rheumatism, deafness, &c. Prod. 20%.

Oil of Beech. Syn. Oleum fagi, L. From the nuts of Fagus sylvatica (Linn.) or beech mast. Clear; keeps well; when washed with hot water, it is used for salads, and burnt in lamps. Sp. gr. ·9225. Prod. 16%.

Oil of Belladon′na. Syn. Oleum belladonnæ seminum, O. b. baccæ, L. From the seeds or berries of Atropa belladonna or deadly nightshade. Yellow; insipid. Used for lamps in Swabia and Wurtemberg, and as an application to bruises. The marc is poisonous. It freezes at 34° Fahr. Sp. gr. ·9250.

Oil of Ben. Syn. Oil of behen; Oleum balatinum. From the seeds of Moringa pterygosperma (ben nuts). Scentless, colourless; keeps long without growing rank; by standing, it separates into two parts, one of which freezes with difficulty, and is hence much used in perfumery.

Oil of Benne Seed. See Oil of Gingelly.

Oil of Brazil-nuts. Syn. Oleum bertholletiæ. From the kernels of the fruit of Bertholletia excelsa, or Brazil-nuts. An oil of a bright amber colour, congealing at 24° Fahr. Sp. gr. ·917. It has been used as a substitute for olive oil in plasters and ointments.

Oil of Caca′o. Syn. Butter of c.; Oleum cacao concretum, Butyrum cacao, L. From the seeds of Theobroma Cacao, or chocolate nuts, gently heated over the fire, and then decorticated, and pressed between hot iron plates. Sp. gr. ·892.

Column headings:

A. Name of Oil.

B. Specific Gravity at 15°C., Water = 1,000.

C. Combustibility. Grms. consumed per hour in a Lamp with Wick.

D. Freezing Point in degrees Centigrade.

E. Colour.

F. Taste.

G. Smell.

H. Limpidity. Time (in seconds) required to trickle a given distance.

I. Drying Power.

A. B. C. D. E. F. G. H. I.

Plum kernel 0·9127 68 -9 Brownish yellow Amygdalaceous Very slight 93 Non-drying.

Rape seed 0·9128 30 -4 Yellow Nauseous Nauseous 159 Non-drying.

Colza 0·9136 40 -9·25 Yellow Nauseous Nauseous 162 Non-drying.

Cabbage seed 0·9139 48·5 -8 Yellow Nauseous Nauseous 148 Non-drying.

White mustard 0·9142 29·8 -16·25 Light yellow Pleasant Very slight 157 Non-drying.

Ground nut 0·9163 ? -3 Pale greenish yellow Like peas Like peas Not tested Non-drying.

Black mustard 0·9170 25 -17·5 Yellow Pleasant Very slight 141 Non-drying.

Olive 0·9176 62 -6[54] Yellow Sweet Peculiar 195 Non-drying.

Sweet almond 0·9180 52·8 -21·5 Amber Agreeable None 150 Non-drying.

Horse-radish seed 0·9187 43 -16·25 Yellowish brown Pleasant None 143 Non-drying.

Grape seed 0·9202 37 -16·25 Gold yellow Sweet None 99 Dries slowly.

Beech nut 0·9225 50 -17·5 Amber Very sweet None 158 Non-drying.

Pumpkin 0·9231 43 -15 Pale brown yellow Sweet None 185 Dries slowly.

Land-cress 0·9240 42 -15 Brownish yellow Acrid Disagreeable 103 Dries slowly.

Hazel nut 0·9242 53·4 -10 Amber Sweet None 166 Non-drying.

Poppy 0·9243 31 -18[55] Pale yellow Flat None 123 Drying.

Camelina 0·9252 34 -18 Yellowish Peculiar Peculiar 119 Drying.

Walnut 0·9260 45 -27·5 Light yellow Flat None 88 Drying.

Sunflower 0·9262 51·8 -16 Colourless Sweet None 114 Dries slowly.

Hemp seed 0·9276 46 -27·5 Dark greenish yellow Disagreeable Disagreeable 87 Drying.

Cotton seed 0·9316 ? -2·5 Reddish brown Strong None Not tested Drying.

Sesame 0·9320 ? -5 Bright yellow Pleasant, slightly piquant None Not tested Non-drying.

Linseed 0·9347 38 -27 Dark greenish yellow Strong Disagreeable 88 Drying.

Wood 0·9358 44 Not noted Green Unpleasant None 73 Drying.

Spindle 0·9360 61 -20 Reddish brown Acrid Slight 143 Non-drying.

Castor 0·9611 47 -18 Colourless Sickly Very slight 1,830 Dries slowly.

Table giving the reactions of various OILS with SULPHURIC ACID and with a saturated solution of BICHROMATE OF POTASH in sulphuric acid. Re-arranged from M. Penot’s table, with additions, by Mr Cooley.

⁂ The result indicated is obtained in each case by the action of one drop of the REAGENT on twenty drops of OIL.

Name of Oil Reagents

Sulphuric Acid Saturated Solution of Bichromate of Potassa in Sulphuric Acid

Not stirred Stirred Stirred

Almond oil Greenfinch yellow, with orange spots Dirty green Yellowish, small lumps

Castor oil Yellow, with slight spots Little reaction Slightly green

Cod-liver oil (fine sample of pale oil) Deep purple in the centre, rapidly turning brown, whilst violet or purple clouds or streaks spread out towards the circumference, the colour of which remains minutes after the central portion turned nearly black Deep purple, passing into purple brown, reddish brown, and gradually deepening to an intense brown, approaching black Reddish-brown clots, changing to a clear bright green

Hemp-seed oil Small brown lumps or clots on a yellow ground Greenish brown Small yellow lumps or clots on a green ground

Linseed oil (from the Upper Rhine) Dark reddish brown Brown small lumps on a grey ground Brown small lumps on an almost colourless ground

(from Paris) Reddish brown, less dark coloured Brown clots on a green ground Brown small lumps on a green ground

(English) Chestnut brown Brown clots on a greenish-grey ground Brown lumps on a greenish-grey ground

Liver-train oil Dark red Dark red Dark red

Madia-sativa oil Slightly reddish brown underneath a thin greyish film Olive green Light brown small lumps on an olive-coloured ground

Black-mustard oil Bluish green Olive green Olive brown

Neat’s-foot oil Yellow slight spots Dirty brown Brown spots on a brownish ground

Nut oil (recent) Yellowish brown Clotted, dark brown Small brown lumps or clots

(one year old) Yellow Dirty brown, less dark coloured Small brown lumps

(still older) Orange yellow Dirty brown Small brownish lumps

Olein, oleic acid, lard, or tallow oil Reddish spots, with reddish circles Reddish brown Bright chestnut colour

Olive oil Yellow Dirty brown Olive brown

(another sample) Orange yellow Brownish grey Brown

(from fermented olives) Orange yellow Brownish grey Brown

Poppy oil (recent cold drawn) Yellow spots Olive brown Small yellow lumps on a white ground

(recent, expressed with slight heat) Greenish-yellow spots Olive brown, turning more on the green Small yellow lumps on a greenish-grey ground

(one year old, expressed with heat) Greenish spots Olive green Small yellow lumps on a green ground

Rape or colza oil (trade) Yellowish-brown streaks surrounded by a bluish-green ring Brownish, turning on the olive green Yellow small lumps on a green ground

(recent) Green Bluish green Yellow small lumps on a green ground

(one year old) Green Bluish green Yellow lumps on a brighter green ground

(one year old, rough hot-pressed) Green Olive green Small yellow lumps, more numerous, on an olive-green ground

Whale-train oil Small reddish lumps on a brownish ground Resembles wine lees Small, bright, chestnut-coloured lumps on a brown ground

Oil, Cas′tor. Syn. Ricini oleum (B. P.), Oleum castorei, O. ricini (Ph. L., E., & D.), L. “The oil prepared by heat, or by pressure, from the seed” of “Ricinis communis, Linn.” (Ph. L.), the Palma Christi, or Mexican oil-bush.

The best castor oil (COLD-DRAWN CASTOR OIL; OLEUM RICINI SINE IGNE)is prepared by pressing the shelled and crushed fruit (seed) in hemp bags, in an hydraulic press, and heating the oil thus obtained along with water in well tinned vessels, until the water boils and the albumen and gum separate as a scum; this is carefully removed, and the oil as soon as it has become cold is filtered through Canton flannel, and put into canisters. The commoner kinds are prepared by gently heating the crushed seeds, and pressing them whilst hot. Another method, sometimes adopted, is to put the crushed seed into loose bags, to boil these in water, and to skim off the floating oil.

Prop. It is the most viscid of all the fixed oils; when pure it mixes in all proportions with alcohol and ether, and also dissolves, to a certain extent, in rectified spirit, but a portion of the oil separates on standing. Camphor and benzoic acid increase its solubility in spirit. By long exposure to the air it becomes rancid, thick, and is ultimately transformed into a transparent yellow mass; light hastens these changes. Exposed to cold, a solid, white crystalline fat separates from the liquid portion, and when cooled to 0° it congeals into a yellow transparent mass, which does not again liquefy until the temperature rises to about 18° Fahr. Sp. gr. ·9611 to ·9612, at 60°; ·9690, at 55° (Saussure); ·9575, at 77° (Saussure). Prod. 38% to 40% (62%—Ure).

Pur. Castor oil is sometimes adulterated with rape oil or with lard oil, a fraud which may be detected by its diminished density; and, when the added oil exceeds 33%, by its insolubility in its own weight of alcohol of ·820. In many cases croton oil is added to increase the purgative quality of the mixture. A compound of this kind is vended in gelatine capsules under the name of ‘CONCENTRATED CASTOR OIL,’ the use of which is fraught with danger. “I have heard of several cases in which very violent and dangerous effects were produced by these capsules.” (Pereira.) The best is imported from the East Indies in tin canisters. The oil obtained from the seeds of Ricinus viridis (Willd.), or lamp-oil seeds, is often mixed with or sold for castor oil.

Uses, &c. Castor oil is an exceedingly useful mild purgative, particularly when abdominal irritation should be avoided, as in inflammations of the stomach and bowels, pregnancy, surgical operations, &c.—Dose, 2 fl. dr. to 1 fl. oz.

Oil, Cocoa-nut. Syn. Cocoa-nut butter; Oleum cocois nuciferæ, L. By expression from the kernels of the cocoa nut, or fruit of the Cocos nucifera.

Oil, Cod-liver. Syn. Morrhuæ oleum (B. P.), Cod-fish oil; Oleum jecoris aselli, O. gadi, O. g. morrhuæ, Oleum morrhuæ (Ph. L.), L. “The oil extracted from the fresh liver of the Gadus morrhua by a steam heat or water bath not exceeding 180° Fahr. Yellow.” “The oil prepared from the liver of Gadus morrhua, Linn.” (Ph. L.)

The common cod-liver oil of commerce drains from the livers of the cod-fish when freely exposed to the sun, and just beginning to putrefy. It is dark coloured, strong, and nauseous, and is now chiefly employed in this country by the curriers, for dressing leather. It is the ‘OLEUM JECORIS ASELLI FUSCUM’ of Continental writers. Formerly, the less fetid varieties of this crude oil, after the impurities were removed, either by subsidence or filtration, constituted the only cod-liver oil used in medicine. As its employment as a remedy increased, its revolting flavour, and its great tendency to permanently disorder the stomach and bowels, was found, however, to be a serious obstacle to its general use. It was observed that the oil as it exists in the liver of the cod is bland and nearly colourless, and has only a slight fishy, but not a disagreeable flavour. The attention of persons interested was therefore immediately directed to the subject, and improved methods of obtaining the oil were suggested, and ere long adopted on the large scale.

The methods of preparing cod-liver oil are noticed in another part of this work, but we think it advisable to add to these a description of the plan adopted by Messrs Charles Fox and Co., of Newfoundland, Scarborough, and London, the well-known manufacturers and importers of cod-liver oil:—

“The Newfoundland fisheries are entirely carried on in small boats, principally by the hand-line system, and quite close to the shore. The boats go out early in the morning, and return about four o’clock in the afternoon. The fish, on landing, are handed over to a ‘fish-room keeper,’ whose duty it is to split and open the fish, and to deposit the livers in small tubs holding 17 or 18 gallons each. The tubs are soon afterwards collected from the different ‘fish-rooms,’ and conveyed to the manufactory. The livers are here thrown into tubs filled with clean cold water, and, after being well washed and jerked over, are placed on galvanised iron-wire sieves to drain. They are next put into covered steam-jacket-pans, and submitted to a gentle heat for about three quarters of an hour, after which the steam is turned off, cold air again admitted, and the whole allowed to repose for a short time, during which the livers subside, and the oil separates and floats on the top. The oil is then skimmed off into tin vessels, and passed through flannel strainers into tubs, where it is left to subside for about 24 hours. From these the purer upper portion of oil is run into a very deep, galvanized-iron cistern, and again left to clarify itself by defecation for a few days. It is now further refined by carefully passing it through clean and very stout mole-skin filters, under pressure. The transparent filtered oil is received in a clean, galvanised-iron cistern containing a pump, from which the casks are filled for exportation. The latter, before being filled, are carefully seasoned and cleaned, to prevent their imparting either flavour or colour to the pure oil.”

The superiority of the oil prepared as above consists essentially in every part of the process of extraction being performed whilst the livers are fresh, and in no chemical means being adopted to give the oil a factitious appearance. Its natural pale colour is thus preserved from contamination, and its medicinal virtues maintained intact.

Much of the light brown oil of commerce is obtained from Gadus callarius (the dorse). G. carbonarius (the coal-fish), and G. pollachius (the pollack).

Pur., &c. “The finest oil,” remarks Dr Pereira, “is that which is most devoid of colour, odour, and flavour. The oil, as contained in the cells of the fresh liver, is nearly colourless, and the brownish colour possessed by ordinary cod-liver oil is due to colouring matters derived from the decomposition (putrefying) of hepatic tissues and fluids, or from the action of the air on the oil (age). Chemical analysis lends no support to the opinion, at one time entertained, that the brown oil was superior, as a therapeutic agent, to the pale oil. Chemistry has not discovered any substance in the brown oil that would confer on it superior activity as a medicine. On the other hand, the disgusting odour and flavour and nauseating qualities of the brown oil preclude its repeated use. Moreover, there is reason to suspect that, if patients could conquer their aversion to it, its free use, like that of other rancid and empyreumatic fats, would disturb the digestive functions, and be attended with injurious effects.”[56]

Among the tests of purity, that generally relied on is known as the ‘sulphuric acid test.’ See Oils (Fixed): Purity.

Dorse oil, and other FISH OIL, sold as ‘LIGHT-BROWN COD-LIVER OIL,’ exhibit with this test much lighter reactions, which closely resemble those of LIVER-TRAIN and WHALE-TRAIN OIL.

To detect the presence of combined iodine, upon which, by some, the therapeutic value of cod-liver oil is thought to depend, the sample is saponified by trituration with a little caustic potassa and hot water, the resulting soap cautiously incinerated, the ashes digested with water, and the whole thrown on a filter. The

The presence of iodine artificially added is best detected by agitating the oil with a little rectified spirit, and then testing this last for iodine. Or, a little solution of starch and a few drops of sulphuric or nitric acid may be at once added to the oil, when a blue colour will be developed if iodine, or an iodide, has been mixed with the sample.

The sp. gr. of the pale oil is ·9230 to ·9238; of the light-brown oil, ·9240 to ·9245; of the dark-brown oil, ·9290 to ·9315. The density is, however, apt to vary a little with the quantity of moisture present.

Uses, &c. Cod-liver oil is a most valuable medicine in a great variety of diseases, more especially in glandular indurations and enlargements, scrofula, phthisis, rheumatism, gout, certain cutaneous diseases, amenorrhœa, chlorosis, caries, rickets, &c. To be of service, however, its use must be continued for several weeks, and the oil must be recent.—Dose, 1 to 2 table-spoonfuls, 3 or 4 times daily, or oftener.

Oil, Col′za. From the seeds of Brassica campestris, var. oleifera, or colza de printemps, a variety of Brassica campestris (Linn.). It may be regarded as a superior sort of rape oil. Burns well in lamps, especially after being refined. Sp. gr. ·9136. Prod. 39%. The term ‘colza oil’ is commonly applied to ordinary refined rape.

Oil, Cottonseed. Syn. Oleum gossipii seminum, L. From the seeds of Gossypium Barbadense. Drying.

Oil, Croton. Syn. Crotonis oleum (B. P.), Oleum crotonis (Ph. E.), O. tiglii (Ph. L.), L. From the shelled seeds of Croton tiglium or Molucca grains. Imported chiefly from the East Indies. It is one of the most powerful cathartics known, and acts when either swallowed or merely placed in the mouth. Externally, it is a rubefacient and counter-irritant, often causing a crop of painful pustules, like tartar emetic.—Dose, 1 to 2 drops, on sugar; in apoplexy, &c. It is poisonous in larger doses. Sp. gr. ·947 to ·953. Prod. Unshelled seeds, 22% to 25%; shelled do., 32% to 35%.

Pure croton oil is soluble in an equal volume of alcohol of ·796, but in 2 or 3 days about 96% of the oil separates. In France the marc is exhausted with alcohol, and the oil thus obtained is added to that previously obtained from the same seeds by expression. The East Indian oil (OLEUM CROTONIS EXOTICUM) is usually of a pale yellow; that pressed in England (o. crotonis Anglicanum) is much darker.

Oil of Cu′cumber. Syn. Oleum cucurbitæ, L. From the seeds of Cucurbita pepo or squash, and the C. melopepo or pumpkin. Pale; used in lamps; and, sometimes, as a soothing application to piles. Sp. gr. ·9231. Prod. 24%.

Oil of Eggs. Syn. Oleum ovi, O. o. vitelli, O. ovorum, L. From the yolks of eggs, gently heated until they coagulate and the moisture has evaporated, and then pressed or broken up, digested in boiling rectified spirit, the tincture filtered whilst hot, and the spirit distilled off. Bland; emollient. The common plan is to fry the yolks hard; but the oil is then darker coloured and stronger. The P. Cod. orders them to be exhausted with ether, by displacement. Formerly commonly used to ‘kill’ quicksilver, and still held in great esteem in some parts of England for sore nipples and excoriations. Prod. 10 to 12 eggs yield 1 oz. See Mixed oils.

Oil of Garden Cress. Syn. Oleum lepidii sativi, L. From the seed. Drying. Sp. gr. ·9240. Prod. 54%.

Oil of Gar′den Spurge. Syn. Oleum lathyris, O. euphorbiæ l., L. From the seeds of Euphorbia lathyris or garden spurge. Cathartic.—Dose, 3 to 8 drops. Sp. gr. ·9281. Prod. 30% to 41%. Croton oil mixed with 6 times its weight of nut or rape oil is usually sold for it.

Oil of Gingel′ly. Syn. Oil of Sesamum, Benne oil, Teel o., Tel o.; Oleum sesami, L. From the seeds of Sesamum orientale (Willd.), or gingelly. Pale; bland. Used in salads, paints, &c.; also to adulterate oil of almonds. Prod. 46%.

Oil, Gourd. See Oil of Cucumber.

Oil of Ground Nuts. From the nuts of Arachis hypogæa. Glutinous.

Oil of Gurgun. See Balsam, Gurgun.

Oil of Hemp. Syn. Oleum cannabis, L. From the seed of Cannabis sativa (Linn.), or common hemp. Mawkish. Sometimes used for frying, but chiefly for paints, soaps, &c. Freely soluble in boiling alcohol; does not thicken until cooled to 5° Fahr. Sp. gr. ·9276. Prod. 18% to 24%.

Oil of Jatro′pha. Syn. Oil of wild castor seeds; Oleum jatrophæ, L. From the seeds of Jatropha purgans. Somewhat resembles CROTON OIL. Used for lamps in the East Indies.

Oil, Kundah. Syn. Tallicoonah o.; Oleum touloucounæ, L. From the fruit of Carapa Touloucouna. Rancid, nauseous, vermifuge, rubefacient, emetic, and purgative. Chiefly used in lamps.

Oil, Lard. Syn. Tallow o., Crude olein, C. oleic acid; Oleum adipis, L. By separating the olein of lard from the stearin by means of boiling alcohol. Only applicable where spirit is cheap. The product is, however, excellent. The crude oleic acid, or lard oil of commerce, is chiefly obtained as a secondary product in the manufacture of stearin. It is purified by agitation with sulphuric acid, and subsequently by steaming it, or washing it with hot water. Burns well in lamps, if the wick-tube is kept cool. Sp. gr. ·9003.

Oil, Linseed. Syn. Oleum lini (B. P., Ph. L., E. & D.), L. 1. (Cold-drawn linseed oil;Oleum lini sine igne.) From the seed of Linum usitatissimum (Linn.), or common flax, bruised or crushed, and then ground and expressed without heat. Pale, insipid, viscous; does not keep so well as the next. Prod. 17% to 20%.

2. As the last, but employing a steam heat of about 200° Fahr. Amber coloured; less viscous than the last; congeals at 2°; soluble in 5 parts of boiling and 40 parts of cold alcohol. Both are drying and cathartic.—Dose, 1 to 2 oz.; in piles, &c. Chiefly used in paints, varnishes, &c. Sp. gr. ·9347. Prod. 22% to 27%.

3. (Boiled linseed oil.) See Oils (Drying).

Oil of Mace (Expressed). See Oil of Nutmeg (Expressed).

Oil of Male Fern. See Extract of Male fern.

Oil of Mustard. Syn. Oleum sinapis, L. 1. (Oil of white mustard.) From Sinapis alba, or white mustard, but chiefly from Sinapis arvensis, S. chinensis, S. dichotoma, S. glauca, S. ramosa, and S. tori. Sweet. Used for the table. Sp. gr. ·9142 (·2160—Ure). Prod. 36%.

2. (Oil of Black mustard; Oleum sinapis nigri, L.) From the ‘hulls’ of black-mustard seed. Viscid, stimulant. Used in rheumatism, Sp. gr. ·9168 to ·9170. See Oils (Volatile).

3. (Oil of White mustard; Oleum raphani, L.) From the seed of Raphanus raphanistrum (Linn.), or jointed charlock or wild mustard. Prod. 30%.

Oil, Neat’s-foot. Syn. Nerve oil, Trotter o.; Oleum bubulum, O. nervinum, Axungia pedum tauri, L. From neat’s-feet and tripe, by boiling them in water, and skimming off the oil. Does not thicken by age. Used to soften leather, to clean fire-arms, and for other purposes.

Oil, Nut. Syn. Hazel-nut o.; Oleum nucis, O. coryli, L. From the kernels of Corylus Avellana (Linn.), or hazel-nut tree. Pale, mild tasted, drying; superior to linseed oil for paints and varnishes. It is commonly sold for oil of almonds and oil of ben, and is extensively employed to adulterate both. Walnut oil is also frequently sold for nut oil. Sp. gr. ·9260. Prod. 63%(Ure).

Oil of Nut′meg (Expressed). Syn. Expressed oil of mace, Butter of m.; Oleum myristicæ (CONCRETUM) (Ph. L.), Myristicæ adeps (Ph. E.), M. butyrum, O. myristicæ expressum (B. P.), O. moschatæ, O. nucistæ, L. “The concrete oil expressed from the seed of Myristica officinalis,” Linn. (Ph. L.), or common nutmeg. The nutmegs are beaten to a paste, enclosed in a bag, exposed to the vapour of hot water, and then pressed between heated iron plates. Orange coloured, fragrant, spicy; butyraceous, or solid. It is a mixture of the fixed and volatile oils of the nutmeg. When discoloured and hardened by age, it is called ‘Banda soap’ (Ol. macis in massis). When pure, it is soluble in 4 parts of boiling alcohol and in 2 parts of ether. It has been used in rheumatism and palsy, but is now chiefly employed for its odour and aromatic qualities. From the East Indies. Prod. 17% to 20%.

Oil, Ol′ive. Syn. Salad oil, Sweet o.; Olivæ oleum (B. P.), Oleum olivarum, O. olivæ (Ph. L., E., & D.), L. The “oil expressed from the fruit” of “Olea europœa, Linn.” (Ph. L.), or common olive. Five different methods are employed to obtain the oil, from the fruit:

1. (Virgin oil; O. o. virgineum, L.); (Huile vierge, Fr.) From olives, carefully garbled, either spontaneously or only by slight pressure, in the cold. That yielded by the pericarp of the fruit is the finest.

2. (Ordinary ‘FINE OIL,’) This is obtained by either pressing the olives, previously crushed and mixed with boiling water, or by pressing, at a gentle heat, the olives from which the virgin oil has been obtained. The above processes furnish the finer salad oils of commerce. The cake which is left is called ‘GRIGNON,’

3. (Second quality.) By allowing the bruised fruit to ferment before pressing it. Yellow; darker than the preceding; but mild and sweet tasted. Much used for the table.

4. (‘Gorgon.’) By fermenting and boiling the pressed cake or marc in water, and skimming off the oil. Inferior.

5. (Oil of the infernal regions; Oleum omphacinum) is a very inferior quality of oil, which is skimmed off the surface of the water in the reservoirs into which the waste water which has been used in the above operations is received, and allowed to settle. The last two are chiefly used for lamps, and in soap-making, &c.

Of the principal varieties of olive oil known in commerce, and distinguished by the place of their production, ‘Provence oil’ is the most esteemed; ‘Florence oil’ and ‘Lucca oil’ are also of very fine quality; ‘Genoa oil’ comes next, and then ‘Gallipoli oil,’ which forms the mass of what is used in England; ‘Sicily oil,’ which has a slightly resinous flavour, is very inferior; and ‘Spanish oil’ is the worst imported.

Prop., &c. Olive oil is a nearly inodorous, pale greenish-yellow, unctuous fluid, with a purely oleaginous taste, peculiarly grateful to the palate of those who relish oil. It does not suffer active decomposition at a heat not exceeding 600° Fahr.; and when cooled to 36°it congeals into a granular solid mass. It is very slightly soluble in alcohol, but its solubility is increased by admixture with castor oil. It is soluble in 1¹⁄₂ part of ether. When pure it has little tendency to become rancid. Sp. gr. ·9170 to ·9173; ·9192, at 53¹⁄₂° (Saussure); ·9176, at 59° (Heidenreich); and ·9109, at 77° Fahr. (Saussure). Prod. 32%, of which 21% is

Pur. Olive oil, with the exception of that of almonds, being the most costly of the ordinary fixed oils of commerce, is, consequently, the one most subject to adulteration. Nut, poppy, rape, and lard oil, are those most commonly used for this purpose. Refined tallow olein, including that obtained from the ‘knackers’ yards’ of Paris, is said to have been used in the same way. The addition of any other oil to olive oil renders it far less agreeable to the palate, and, by increasing its tendency to rancidity, much more likely to offend and derange the stomach and bowels of those who consume it. Parties who indulge themselves in the use of this luxury would, therefore, do well to ascertain that what they purchase is pure. When pure, and also fresh, olive oil is most wholesome as an article of food or us a condiment.

The detection of the sophistication of salad oil is a matter of no great difficulty. The palate of the connoisseur will readily perceive the slightest variation in the quality of his favourite condiment. Other methods, however, of a more accurate and certain description, and of more general application, are adopted. Amongst these, in addition to those mentioned above, are the following:—

a. When pure olive oil is shaken in a phial, only half filled, the ‘bead’ or bubbles rapidly disappear; but if the sample has been mixed with poppy or other oil, the bubbles continue longer before they burst.

b. Olive oil congeals at 36° Fahr., and is completely solidified when a small bottle containing it is surrounded by ice, or a freezing mixture; but when mixed with poppy oil, it remains partly liquid, even when the latter forms only 1-4th of the mass; if more than 1-3rd of poppy oil is present, it does not solidify at all, unless cooled much below the freezing point of water.

c. (Ph. E.) When olive oil is “carefully mixed with ¹⁄₁₂th part of its volume of a solution of 4 oz. of mercury in 8 fl. oz. 6 dr. of nitric acid (sp. gr. 1·500), it becomes in 3 or 4 hours like a firm fat, without any separation of liquid oil.”

d. M. Pontet recommends the mercurial solution to be made by dissolving 6 parts of mercury in 7¹⁄₂ parts of nitric acid (sp. gr. 1·35), without heat; of this solution he adds 1 part to every 48 parts of the oil, and well shakes the mixture every 30 minutes, until it begins to solidify. This it does after about 7 hours in summer and 4 or 5 hours in winter, and when the oil is pure it will have formed, in 24 hours, a mass so hard that some little force must be employed to thrust a glass rod into it. The other edible oils do not furnish a hard mass with nitrate of mercury. The solidity of the mass is exactly in proportion to the quantity of foreign oil present. When the sophistication is equal to 1-8th of the whole, a distinct liquid layer separates; when the mixture contains half its volume of an inferior oil, one half only of the mixture becomes solid, and the other half continues liquid. A temperature of about 90° Fahr. is the best to cause the oil and coagulum to separate perfectly from each other. When the oil has been adulterated with animal oil, the mixture solidifies in about five hours; but in this case the coagulum consists of the animal oil, whilst the olive oil floats on the surface, and may be decanted for further examination. This coagulum, on being heated, exhales the well-known odour of rancid fat or melted tallow.

e. Dr Ramon Cordina Langlies states that the best reagent for the examination of olive oil is that of Hauchecorne.

This reagent is composed of three parts of pure nitric acid at 40° with one part of distilled water. The following is Dr Langlies’ process for proving that olive oil does not contain seed oil, and more especially cotton oil:—

He mixes three grammes of the oil to be tested with one gramme of the reagent in a test tube, or a small stoppered flask, and heats the liquid in a water bath. If the oil is pure the mixture becomes clearer, and takes a yellow colour, like purified oil; if it is adulterated with seed oil, it acquires the same transparency as the pure oil, but becomes red. With 5 per cent. of seed oil the reddish colouring is characteristic; with 10 per cent. it is decided. The reaction does not require more than from 15 to 20 minutes.

The colouring of the oils lasts for three days.

Uses, &c. The dietetical uses of olive oil are well known. In Spain and Italy it is commonly employed as a substitute for butter. It is highly nutritious, but is digested with difficulty by some persons, and hence should be avoided by the dyspeptic. Like almond oil, it is occasionally employed as a laxative and vermifuge, and is, perhaps, one of the mildest known. In pharmacy it is extensively employed in the preparation of cerates, liniments, ointments, and plasters.—Dose. For an adult, ¹⁄₂ to 1 wine-glassful as a mild aperient; for an infant, ¹⁄₂ to 1 teaspoonful, mixed up with an equal quantity of honey, syrup of roses, or syrup of violets. The white fibrous sediment which forms in the recently expressed oil is the ‘AMURCA’ of Pliny, and was formerly highly esteemed in medicine.

Oil, Olive, Droppings. Syn. Sweet-oil d. The ‘foots’ or ‘deposits,’ and the ‘drippings’ of the casks, cisterns, and utensils. Used for machinery, making soap, &c.

Oil, Olive (Oxygenated). Syn. Oleum olivæ oxygenatum (Ph. Batav.), L. Olive oil, 16 oz., is placed in a receiver surrounded with ice or very cold water, and chlorine is slowly transmitted through it for several days, or until

Oil, Palm. Syn. Palm butter; Oleum palmæ;, L. From the fruit of Elais Guineensis, and E. melanococca, the Guinea oil palms. Orange or red coloured; butyraceous or solid; smells of violets; unchanged by alkalies; bleached by sunlight, age, exposure, chlorine, chromic acid, and oil of vitriol; melts at 117¹⁄₂° Fahr. Sp. gr. ·968. Demulcent. Used to colour and scent ointments, pomades, &c.; but chiefly to make soap and candles. From Africa.

Oil, Pi′′ney. Syn. Piney tallow, P. dammar, P. resin. From Vateria Indica (Linn.) or pænoe tree. Resinous flavoured, fragrant, made into candles. Sp. gr. ·926.

Oil, Pop′py. Syn. Oleum papaveris, L.; Oliete, Huile blanche, Fr. From the seeds of Papaver somniferum (Linn.), or white poppy. Sweet; pale; dries and keeps well. Used for salads, paints, and soaps; also (extensively) to adulterate almond oil, for the inferior qualities of which it is frequently sold. It does not freeze until cooled to 0° Fahr. Sp. gr. ·9243 to ·9245. Prod. 48% to 54%.

Oil of Pumpkin. Syn. Oleum cucurbitæ. Expressed from the seeds of the pumpkin; a soothing application to piles.

Oil, Rape. Syn. Colza oil, Brown o.; Oleum rapæ, L. From the seed of Brassica napus (Linn.; cole or rape), and from Brassica campestris (Linn.; wild navew or rape). Glutinous; buttery at 25° Fahr. Dries slowly; makes soft soaps and good ointments, but bad plasters; smokes much in burning, unless well refined. Sp. gr. ·9135 to ·9136. Prod. 32%.

Oil, Refined or PALE RAPE (Oleum rapæ refinum, Ol. r. album) is prepared from crude rape oil, by agitating it with about 2% of oil of vitriol, previously diluted with about twice its weight of water, and, after 10 or 12 days’ repose, decanting the clear oil, and filtering it through Canton flannel or felt. The quality is improved by washing it with hot water or steam before filtration. Used for lamps, blacking, and machinery; also extensively employed to adulterate both almond and olive oil. It forms the common ‘SWEET OIL’ of the oilmen and druggists. Sp. gr. ·9136 to ·9140.

Oil, Seal. Syn. Oleum phocæ, L. From the hood seal, and harp seal, and other species of Phocidæ. Pale seal oil is that which drains from the blubber before putrefaction commences, and forms about 60% of the whole quantity of oil obtained. It is very clear, free from smell, and, when recently prepared, not unpleasant in its taste. Refined seal oil is the last, washed and filtered. Ranks close after sperm oil. Brown or DARK SEAL OIL is that which subsequently drains from the putrid mass. It is very strong-scented and nauseous, and smokes in burning. Both are used for lamps and dressing leather. A full-grown seal yields 8 to 12 galls. of oil; a small one, 4 to 5 galls.

Oil of Ses′amum. Syn. Oil of Gingelly (above).

Oil, Shark-liver. The lightest of the fixed oils. Sp. gr. ·865 to ·867.

Oil, Skate. Syn. Oleum ralæ, L. From the livers of Raia batis (Linn.), or common skate, as cod-liver oil; also from Raia rhinobatus, or white skate, and Raia clavata, or thornback. Often sold and mixed with cod-liver oil.

Oil, Spermace′ti. Syn. Sperm oil; Oleum cetacei, L. From the ‘head matter’ of Physeter macrocephalus, or spermaceti whale; a species once common in all the principal seas, but now chiefly confined to the Southern Ocean. It is very limpid, smells little, and burns well; and has long been reputed the best oil for lamps and machinery, as it does not thicken by age or friction. It is frequently adulterated with refined seal oil. Sp. gr. ·875.

Oil, Sun′flower. Syn. Oleum helianthi, L. From the seeds of Helianthus annuus and H. perennis. Clear, pale yellow, tasteless; thickens at 60° Fahr. Used for salads and lamps. Sp. gr. ·9261. Prod. 15%.

Oil, Teel. See Oil, Gingelly.

Oil, Tobac′co-seed. Syn. Oleum tabaci (expressum), L. From the seeds of Nicotiana tabacum (Linn.), or true tobacco plant. Pale; dries well; equal to nut oil. Its production has recently been carried on with considerable success in some parts of Russia. Sp. gr. ·9232.

Oil of Touloucou′na. See Oil, Kundah.

Oil, Train. See Oil, Whale.

Oil, Wal′nut. Syn. Oleum juglandis, O. nucis j., L. From the kernels of the nuts of Juglans regia (Linn.), or common walnut tree. Soon gets rank; dries well. Used in paints, and occasionally in plasters. When ‘cold drawn’ and washed it is sometimes eaten with salad. Sp. gr. ·9260 to ·9262. Prod. 48% to 52%.

Oil of Wax. Syn. Butter of wax; Oleum ceræ, L. From beeswax, by quick distillation in a close vessel. Butyraceous. By rectification along with quicklime it yields a liquid oil.

Oil, Whale. Syn. Train oil, Whale-train o.; Oleum balænæ, O. ceti, L. From the blubber of the Balæna mysticetus (Linn.), or the common or Greenland whale, by heat. Coarse; stinking. Southern whale oil is the best. Used for lamps, machinery, &c. Sp. gr. ·9231. Prod. per fish, about 1¹⁄₂ ton for each foot of bone.

Oil of Wheat. Syn. Oleum tritici, L. From bruised Colne wheat, with heat. In chilblains, ringworm, and several other skin diseases.

Oil of Wine-stones. Syn. Grape-stone oil; Oleum vitis viniferæ lapidum, L. From the seeds of grapes, separated from the marc.Prod. 14% to 18%.

⁂ The numbers given above, under ‘products,’ unless when otherwise stated, refer to the respective fruits, kernels, nuts, seeds, &c., deprived of their husks, pods, shells, and every other portion destitute of oil.

OILS (Medicated). Syn. Olea cocta, O. infusa, O. medicata, L. These are prepared by infusion or decoction. The bruised ingredients are either simply digested in 2 to 4 times their weight of olive oil for some days, or they are gently boiled in it until they become dry and crisp, great care being taken that the heat towards the end of the process is not greater than that of boiling water. As soon as the process is complete, the oil is allowed to drain from the ingredients, which are then (if necessary) submitted to the action of the press. The product is commonly run through flannel or a hair sieve whilst still warm, after which it is allowed to repose for a week or ten days, when the clear portion is decanted from the dregs. The green or recent plants are usually employed for this purpose, but, in many cases, the dried plants, reduced to powder, and digested for 6 or 8 hours in the oil, at the heat of hot water, with frequent agitation, yield a much more valuable product. They are nearly all employed as external applications only.

⁂ The following are the most important preparations of this class:—

Oil of Adder’s Tongue. Syn. Oleum ophio glossi, L. From the herb, as OIL OF BELLADONNA. A popular vulnerary.

Oil of Ants. Syn. Oleum formicarum. Digest 4 oz. of ants in 16 oz. (by weight) of olive oil with a gentle heat, and strain.

Oil of Bal′sam Apple. Syn. Oleum balsaminæ. Prep. Balsam apple (deprived of seeds), 1 oz.; oil of almonds, 4 oz.; digest and strain.

Oil of Belladon′na. Syn. Oleum belladonnæ (P. Cod.), L. Prep. From the fresh leaves, bruised, 1 part; olive oil, 4 parts; digested together at a gentle heat until the moisture is evaporated; the oil is then strained off with pressure, and filtered.

Oil of Cantha′rides. Syn. Oleum cantharidis, O. cantharidibus, L. Prep. (P. Cod. 1839). From Spanish flies (powdered), 1 part; olive oil, 8 parts; as Oil of Belladonna. Stimulant and rubefacient. Used as a dressing to indolent sores, blisters, &c.; and in dropsy, rheumatism, gout, &c., Oil of the oil-beetle (Meloe proscarabæus—Linn.) is prepared in a similar manner.

Oil of Cap′sicum. Syn. Oleum capsici, L. Prep. (Dr Turnbull.) From powdered capsicum or Cayenne pepper, 4 oz., olive oil, 1 pint; digested together for 6 hours, with heat, and strained. Stimulant; rubefacient in colic, cholera, &c.

Oil of Cham′omile. Syn. Oleum anthemidis, Ol. chamæmeli, L. From the dried flowers (rubbed to pieces), 1 part, olive oil, 8 parts; digested together, with heat, for 6 hours. Stimulant, emollient, and vermifuge.

Oil of Col′ocynth. Syn. Oleum colocynthidis, L. From the pulp, as Oil of Chamomile. Diuretic. In dropsy, neuralgia, rheumatism, worms, &c.

Oil of Earth′worms. Syn. Oleum lumbricorum. (E. Ph. 1744.) Washed earthworms, ¹⁄₂ lb.; olive oil, 1¹⁄₂ pint; white wine, ¹⁄₂ pint. Boil gently till the wine is consumed, and press and strain.

Oil of Elder-flowers. Syn. White oil of elder; Oleum sambuci album, O. sambucinum (P. Cod.), L. Prep. From the flowers, as Oil of Chamomile. Emollient and discussive.

Oil of Elder-leaves. Syn. Green oil, Green oil of elder, Oil of Swallows; Oleum viride, O. sambuci viride, L. Prep. 1. Green elder leaves, 1 lb.; olive oil, 1 quart; boil gently until the leaves are crisp, press out the oil, and again heat it till it turns green.

2. As before, but by maceration, at a heat under 212° Fahr. More odorous than the last.

3. Elder leaves, 1 cwt.; linseed oil, 3 cwt.; as No. 1.

Obs. The last form is the one usually employed on the large scale. It is generally coloured with verdigris, ¹⁄₂ lb. to the cwt., just before putting it into the casks, and whilst still warm; as, without great skill and a very large quantity of leaves, the deep-green colour so much admired by the ignorant cannot be given to it. The oil is got from the leaves by allowing them to drain in the pan or boiler (with a cock at the bottom), kept well heated. Emollient; in great repute among the vulgar as a liniment, in a variety of affections.

Oil of Fen′ugreek. Syn. Oleum fœnugræci, L. Prep. (P. Cod.) From the seeds, as Oil of Cantharides or of CHAMOMILE. Emollient and resolvent.

Oil of Fox′glove. Syn. Oleum digitalis, L. Prep. (P. Cod.) From the fresh leaves, as Oil of Belladonna. Used as an application to chronic ulcers and indurations, painful swellings &c. As usually met with, it is nearly inert.

Oil of Garden Night′shade. Syn. Oleum solani, L. Prep. (P. Cod.) From the leaves, as Oil of Belladonna. Anodyne and discussive.

Oil of Gar′lic. Syn. Oleum allii infusum, L. From garlic, as Oil of Belladonna. Used as a liniment in deafness, diarrhœa, infantile convulsions, palsy, rheumatism, &c.

Oil, Green. Syn. Oleum viridi, L. From bay leaves, origanum, rue, sea wormwood, and elder leaves, of each 2¹⁄₂ oz.; olive oil, 1 quart; as Oil of Elder. Detergent, stimulant, and

Oil of Hem′lock. Syn. Oleum conii, L. Prep. (P. Cod.) As Oil of Belladonna. Anodyne and emollient; in painful ulcers, glandular tumours, &c.

Oil of Hen′bane. Syn. Oleum hyoscyami, L. Prep. (P. Cod.) As Oil of Belladonna. Used as the last, in various painful local affections.

Oil Iodizeo, Marshall’s. Syn. Oleum iodatum. Prep. Oil of almonds, 15 parts; iodine, 1 part. Triturate and digest till dissolved.

Oil of Ju′′niper (by Infusion). Syn. Oleum juniperi infusum, L. From the crushed berries, as Oil of Belladonna. Diuretic and vulnerary; in frictions, &c.

Oil of Lil′ies. Syn. Oleum liliorum, L. From white lilies, 1 lb.; olive oil, 3 lbs.; as Oil of Belladonna. Emollient; used to soften and ripen tumours, indurations, &c.

Oil of Mel′ilot. Syn. Oleum meliloti, L. As the last, avoiding much heat. Emollient and resolvent.

Oil of Mu′cilages. Syn. Oleum mucilaginum, O. cum mucilaginibus, L. Prep. 1. (Ph. L. 1746.) Marshmallow root, ¹⁄₂ lb.; linseed and fenugreek seed, of each, bruised, 3 oz.; water, 1 quart; boil 1 hour, add of olive oil, 2 quarts, and boil until the water is consumed.

2. Fenugreek seeds, 8 oz.; linseed oil, 1 quart; infuse a week, and strain. Once a highly popular emollient application in various local affections.

Oil of Mu′dar. Syn. Oleum mudaris, L. From mudar bark (in coarse powder), 1 dr.; warm olive oil, ¹⁄₄ pint; digest 24 hours and strain. Used as an application to cutaneous ulcers, the bites of venomous animals, &c., and as a friction in worms.

Oil of O′′pium. Syn. Anodyne oil, Opiated o.; Oleum opiatum, L. Prep. From opium (in powder), 1 dr.; olive oil, 2¹⁄₂ fl. oz.; digest at a gentle heat, with frequent agitation, for 5 or 6 hours. The powder should be rubbed in a mortar with a few drops of the oil before adding the remainder. As a local anodyne. The above is the only reliable formula for this preparation. Others are extant, but whilst the products of several are much stronger, those from others have only 1-5th or 1-6th the strength.

Oils, Ozonised. (Dr Thompson.) Syn. Oleo ozonata. Prep. Pass oxygen gas into the oil (cocoa nut, sunflower, cod-liver oil, &c.) until it will dissolve no more. Then expose for a considerable time in the direct rays of the sun. Used in phthisis.

Oil of Pel′litory. Syn. Oleum pyrethri, L. From bruised pellitory root, as OIL OF BELLADONNA. Used as the last.

Oil of Black Pep′per (by Infusion). Syn. Oleum piperis infusum, L. From black pepper, in coarse powder, as Oil of Capsicum. Stimulant and rubefacient; in frictions.

Oil of Poison Oak. Syn. Oleum rhois toxicodendri, L. From the leaves, as OIL OF BELLADONNA Externally; in paralysis, &c.

Oil of Rhu′barb. Syn. Oleum rhei, L. From rhubarb (in powder), 1 part; oil of almonds, 8 parts; digested together in a gentle heat for 4 hours, and strained, with expression. As an application to indolent ulcers, and as a friction over the abdomen in diarrhœa, English cholera, &c., or as a laxative when the stomach will not bear medicine.

Oil of Ro′′ses. Syn. Oleum rosæ, O. rosaceum, O. r. infusum, O. rosatum, L. Prep. From the fresh petals, pulled to pieces, crushed, and digested for 2 or 3 days in the sun, or a warm situation, in 4 times their weight of olive oil, and then pressed; the process being repeated with fresh roses. Ph. E. 1744 and P. Cod. are nearly similar. Almond, BEN, or OLIVE OIL, coloured with ALKANET, and scented with attar of roses, is now almost universally sold for it. Used for the hair.

Oil of Rue. Syn. Oleum rutæ (infusum), L. Prep. (P. Cod.) From fresh rue, bruised, as Oil of chamomile. Reputed antispasmodic, emmenagogue, stimulant, and vermifuge. In frictions.

Oil of St John’s Wort. Syn. Oleum hyperici (Ph. L. 1746), O. h. simplex, Balsamum h., L. From the flowers, 1 part; olive oil, 6 parts; digested together until the oil is well coloured. Antispasmodic, stimulant, and resolvent. A mixture of equal parts of RAPE OIL and GREEN ELDER OIL is usually sold for it.

Oil of Scam′mony. Syn. Oleum scammonii, O. purgans, L. Prep. (Van Mons.) From scammony (in powder), 1 dr.; hot oil of almonds, 3 fl. oz.; triturate together until cold, and the next day decant the clear portion.—Dose, ¹⁄₂ to 1 table-spoonful.

Oil of Stramo′′nium. Syn. Oleum stramonii, L. Prep. (P. Cod.) From the leaves of thorn apple or stramonium, as OIL OF BELLADONNA. Anodyne and discussive; as an application to painful tumours, joints, &c.

Oil of Tobac′co (by Infusion). Syn. Oleum tabaci, O. t. infusum, L. From fresh tobacco leaves (bruised), like OIL OF CHAMOMILE. As an application in ringworm, irritable ulcers, pediculi, &c.; and as a friction in itch, neuralgia, painful indurations, &c. It must be used with extreme caution, as it is poisonous.

Oil of Tooth′wort. Syn. Oleum squamariæ, L. From the herb of Lathræa squamaria (Linn.), as Oil of St John’s wort. Astringent and vulnerary. This must not be confounded with another preparation sometimes called ‘Oil of toothwort’ (Oleum plumbaginis Europææ),and which has been occasionally used in itch, as the latter is acrid and apt to cause much irritation.

Oil of Worm′wood. Syn. Oleum absinthii,OIL OF LILIES. The P. Cod. and Ph. Wurtem. order only part of the herb to 8 parts of oil. Applied to the abdomen in dyspepsia, diarrhœa, heartburn, worms, &c. It is seldom used in this country.

OILS (Mineral). Syn. Hydrocarbon oils. An important class of liquids, consisting solely of carbon and hydrogen—the elements of ordinary coal-gas, and obtained by the distillation of coal, lignite, petroleum, and other bituminous substances. For the purposes of illumination, many of these oils are in most respects superior to the fixed or fat oils containing oxygen. They give a whiter and more brilliant light, and are produced at a much lower cost. The lamps in which they are burnt, when properly constructed, are less liable to get out of order than those adapted for the combustion of fat oils, and require less attention when in use. The experiments of Dr Frankland on the relative value of the ordinary illuminating agents[57] prove that the mineral oils are cheaper than all other portable illuminating agents in common use, and that they give, while burning, the largest amount of light with the least development of heat, and the smallest production of carbonic acid. With the oils adapted for burning in lamps other oils are produced. Some are very volatile and highly inflammable, and the safety of the burning oils depends on their proper extraction. These volatile liquids, when isolated, are used in the arts as substitutes for spirits of turpentine, as solvents for various substances, and to increase the illuminating power of coal-gas. Others are of a greasy nature, and are too heavy to be conveniently used in lamps. These, however, are well adapted for lubricating fine machinery, and are extensively employed instead of sperm oil by the cotton manufacturers of Lancashire. When the more volatile ingredients are separated from the burning oils, the latter are perfectly safe. Most of the mineral burning oils now in use are, we believe, free from danger in this respect. (See Tests, below.)

Hist. For many years the manufacture of burning oils by the distillation of bituminous schists has been extensively carried out on the Continent, but the discovery which formed the foundation of the modern manufacture was made nearly thirty years ago by our countryman, Mr James Young. This gentleman took the lease of a spring of petroleum in 1847, and after numerous experiments succeeded in obtaining two useful oils from the crude liquid; the one being adapted for lubricating machinery, and the other for burning in lamps. The almost total cessation of the flow of petroleum terminated the business after two years’ working, and led Mr Young to institute a series of experiments to try if petroleum could be produced artificially by the destructive distillation of coal. These experiments resulted in the discovery of an oil which Mr Young named ‘Paraffin oil,’ as it had many of the chemical properties of the solid body of paraffin, discovered twenty years before by Reichenbach in beech-wood tar. Young’s patent (dated Oct. 7, 1850) involved the slower distillation of coals, at a lower temperature than had hitherto been employed for the purpose, and this novelty in practice was followed by the novel result of a copious production of liquid hydrocarbons. The gas or cannel coals were found to yield the liquids in largest quantities, that variety known as Boghead coal or Torbane Hill[58] mineral being specially adapted for the patented process. (See Paraffin oil, below.) Soon after Young’s discovery native petroleum was brought from Rangoon, and purified by distillation, so as to produce oils very similar to the coal products. During the last few years, however, rich sources of petroleum have been discovered in North America, and from whence are imported the greater part of the vast quantities of petroleum oil (both for burning and lubricating purposes), together with the paraffin spirit, or naphtha, which are consumed in this country.

In the following table are given the quantities of these substances sent into England and Scotland during the year 1875:—

Refined burning Oil. Lubricating Oil. Residuum. Petroleum Spirit.

Barrels. Cases. Barls. & Casks. Barrels. Cases. Barrels.

London 169,762 3,250 2,511 1,000 ... 53,173

Liverpool 95,853 2,830 300 29,358 ... 30,913

Hull 20,226 8 ... ... ... ...

Bristol 36,889 1,392 ... ... ... 17,203

Clyde and Leith 4,233 4 535 9,387 ... ...

——— ——— ——— ——— ——— ———

Total 326,963 7,484 3,346 39,745 ... 101,289

This amounts to about 17 millions of gallons. In 1874 it exceeded 20 millions of gallons, but the stock in hand at the end of 1874 was about 5 millions of gallons, and the end of 1875 was only 1¹⁄₂ million. The difference was mainly due to overtrading in 1874, which brought refined petroleum to the lowest price yet known in England, viz. 7³⁄₄d. per gallon in December, 1874, and checked its subsequent importation.[59]

Tests, Precautions. The Sanitary Commission of the ‘Lancet’ took as the limit of safety an oil that gave off inflammable vapour when heated to 130° Fahr., and this has been generally accepted by dealers. If an oil gives off inflammable vapours before being heated up to 130°, it is considered unsafe for domestic use.

1. The plan for testing this, recommended in the ‘Lancet,’ is to heat a portion of the suspected oil in a gallipot placed in boiling water, ascertaining by a thermometer suspended in the oil the temperature at which it will take fire on the surface when a lighted wax vesta is applied to it. This is a troublesome and dangerous process, and has little practical value.

2. A rough-and-ready method of testing the inflammability of a sample is to pour a little out on a dry flat board, and try whether it can be ignited readily by a lighted paper. If it catches fire like turpentine or brandy, the oil is dangerous.

3. The following plan, proposed by Mr

“Take an earthenware dish, holding about half a pint (a breakfast cup will do), fill the cup full from a kettle of boiling water, pour this into an earthenware quart jug, then fill the same cup again with boiling water from the kettle, and pour it also into the quart jug, then fill the cup with cold water, put it into the jug, shake the jug to mix the hot and cold water, then pour the tepid water from the jug into the cup till the cup is half full, then pour about a table-spoonful of the oil to be tested on the tepid water in the cup, take the oil-can with the oil out of the room, then touch the surface of the oil in the cup with a lighted splinter of wood, or a match without sulphur. If the match causes a flash of flame to appear on the surface of the oil, the oil is below the standard of safety, and should not be used; if no flame appears, the oil is up to the standard. We may mention that in this trial no time should be lost after pouring the boiling water from the kettle, as the water may get too cold, but the whole may be gone through in from two to three minutes. It is well to have a saucer at hand, and if the oil should be a bad oil, and ignite with the match, place the saucer on the mouth of the cup, and the flame is extinguished. This trial should be done by daylight, and at a distance from a fire, and the directions must be followed exactly in the order as given above.”

4. Provided that the oils to be examined have been produced by careful fractional distillation, their relative volatility, as indicated by their specific gravity, shows to a great extent the facility with which they ignite. The lightest oils are more volatile and more easily inflamed than those which are heavier. Oils much under ·800 inflame directly a lighted match is thrown into them, whereas oils at about ·815 to ·823 (if unmixed products) cannot be set on fire in this manner. The specific gravity test cannot, however, be depended on to determine the inflaming point of any commercial oil. A heavy oil, badly rectified, may contain a proportion of very volatile vapour, and have a low inflaming point; whereas a much lighter oil may be perfectly safe, from its having the more volatile portions carefully removed.

5. (Van der Weyde.) The oil to be tested is placed in a graduated tube closed at one end; the open end is then closed with the finger, and is then placed mouth downwards in a vessel of water that is heated from 43°—44° C. The vapour from the portion volatilised at this temperature then collects in the upper part of this tube, and expels a corresponding quantity of oil. See Petroleum.

In Great Britain petroleum is defined by Act of Parliament as being any oil which gives off all inflammable vapour at a temperature less than 100° F.

To prevent accidents with paraffin or petroleum lamps, the following precautions ought to be observed:—

The lamps should be filled and trimmed by daylight.

They should never be overfilled; the oil should not be allowed to come into contact with the metal work of the burner.

Any portion of oil spilled on the outside of the lamp should be carefully wiped away.

When not in use the wick should be turned down into the wick-holder.

⁂ The principal products noticed below rank high among the numerous varieties of mineral oil now in the market, but there are doubtless many others equally good and safe. Their properties are described in accordance with the results obtained by Mr W. B. Tegetmeier, who has devoted much time to the examination of the mineral oils:—

Oil, Al′bertite. From ‘Albertite,’ a lustrous black mineral found in New Brunswick. A sample was shown in the Colonial Department of the International Exhibition of 1862, but the oil has not yet appeared in the English market.

Prop. Odour very slight; illuminating power high; boiling point 338° Fahr., or 126° above that of water.

Oil, American. See Petroleum oil (below).

Oil, Apyroec′tic. Syn. Non-explosive oil. A burning oil, introduced by F. Tall, of Hull, and prepared, we believe, from American petroleum.

Prop. Slightly coloured; perfectly limpid; odour slight, but not perceivable during combustion. The most remarkable property of this oil is that, in spite of its limpidity, the point at which it gives off inflammable vapour is 180° Fahr., or 80° above the requirements of the Petroleum Act.

Oil, Bel′montine. From Rangoon tar, or Burmese petroleum, by distillation; superheated steam being employed as the heating agent.

Prop. Colourless; odour not unpleasant; sp. gr. ·847; but although so heavy, the oil is altogether free from viscosity, and will rise rapidly in a comparatively long wick; inflaming point 134° Fahr.; burns with an exceedingly white light, and possesses a very high illuminating power.

Obs. The distillation of the Rangoon tar is carried on by Price’s Patent Candle Company under a patent. Besides the above lamp oil, several beautiful and useful products are obtained. At first there comes over a very volatile liquid, termed Sherwood oil, used as a detergent for removing grease from fabrics, cleaning gloves, &c.; then comes the Belmontine oil, already noticed; then two lubricating oils, the one light and the other heavy; and, last of all, when the temperature is considerably elevated, the beautiful white, translucent solid known as Belmontine, distils over. This last is a kind of paraffin, and is used for making ornamental candles.

Oil, Caz′eline. An excellent burning oil, probably prepared from American petroleum, introduced by Cassell, Smith, and Co., of London.

Prop. Bright, limpid, with scarcely a trace of colour; odour very slight, and quite free from any objectionable character; sp. gr. ·805; lowest point of ignition 144° Fahr.; burns with a pure white light, free from smoke and smell.

Oil, Col′zarine. A heavy hydrocarbon oil, adapted for burning in lamps constructed from the old ‘Moderators’ and ‘Carcels,’ formerly so much used for the fat oils.

Prop. Limpid; quite inodorous; of a pale amber colour; sp. gr. about ·838; temperature at which the vapour can be permanently ignited, 250° Fahr. Tested in the altered moderator, it gives an intense white light, without smoke or smell. Compared with vegetable colza oil, its illuminating power is in the proportion of 3 to 2.

Obs. This oil is manufactured by Cassell, Smith, and Co., under Martin’s patent for the modification of mineral oils, to fit them for burning in lamps where ‘colza’ and other vegetable and animal oils have been usually consumed. Similar oils are prepared by other firms.

Oil, Machin′ery. Syn. Lubricating oil, Shafting o., Spindle o. The heavier hydrocarbon, oils obtained in distilling coal, shale, and petroleum, have almost superseded the fat oils for lubricating purposes. They have no chemical action on the ordinary metals, and are not affected by cold. The lightest of these comparatively heavy oils are used for spindles, or other kinds of rapid machinery; the heaviest for the bearing parts of heavy machinery; and those of an intermediate character for such things as printing-presses, agricultural steam-engines, &c. In America and on the Continent this oil is also used for making gas. The firm of Whitmore and Craddock is favorably known for the manufacture and purification of these machinery oils. See Oil, Belmontine (above), and Oil, Paraffin (below).

Oil, Pa′raffin. Syn. Paraffine oil. This name was given by Mr Young to the oil produced by the distillation of cannel coal, Boghead coal, &c., at a temperature considerably lower than that employed in the manufacture of illuminating gas. The following is a brief outline of Mr Young’s process:—

Manuf. (Young’s patent.) Boghead coal, broken into small fragments, is introduced into perpendicular tubes or retorts, about eleven feet in height, by conical hoppers at their upper extremities. Four of these tubes constitute a set, being built into one furnace, and charged by a single workman. They pass completely through the furnace, and are closed below by dipping into shallow pools of water, while the openings into the hoppers above may be shut by spherical valves. The coal in each tube is gradually heated as it descends to that part which passes through the furnace, and when it reaches the bottom of the tube it has parted with its volatile constituents, and is raked away as refuse, the coal from above descending as it is removed. Thus, the action of these perpendicular retorts is continuous, and the distillation goes on uninterruptedly both day and night. The vapours produced are conducted by iron tubes to the main condensers, which consist of a series of syphon pipes freely exposed to the air. The quantity of incondensible gas formed is inconsiderable; and it is this result, so different from that obtained in the ordinary gasworks, that marks the great value of Young’s process. The crude oil, a dark-coloured, thick liquid, is then distilled to dryness in large iron cylindrical stills, and is thus freed from the excess of carbon which is left behind as coke. The oil, after distillation, is further purified by being acted upon by strong sulphuric acid (oil of vitriol), which chars the principal impurities, and causes them to subside in the form of a dense black, heavy acid tar. To separate the remaining impurities, and that portion of the sulphuric acid which remains in the oil, it is next subjected to the action of caustic soda. As thus purified, the paraffin oil contains four distinct commercial products. To effect their separation, the process of fractional distillation is first employed.below. The third product in point of volatility is a comparatively heavy liquid (machinery oil), largely used for lubricating purposes in the Lancashire factories. From this oil, and others which come over at a very high temperature, the fourth commercial product is separated by the action of artificial cold. This last product is the beautiful translucent solid, paraffin, now much used as a candle material.[60] (See Oil, Paraffin, Petroleum.)

In the preparation of paraffin oil, from native petroleum, the oil is obtained by direct distillation from the petroleum, and subsequently separated from the more or less volatile hydrocarbons (the paraffin naphtha, the lubricating oils and the solid paraffin) that are associated with it by fractional distillation as in Young’s process; whereas, when procured from bituminous minerals, it is derived from the tar or crude oil, which has to be previously extracted from the bituminous matters by destructive distillation. There are various methods for obtaining this tar or crude oil, which, although differing in detail, are in general principles very similar to that described in Young’s patent. Thus, whilst in many works closed horizontal retorts are employed, in other establishments vertical ones, to the bottoms of which are attached receptacles for the receipt of the exhausted coal or other material as it falls from the retort, the same as in Young’s apparatus, are extensively adopted. When horizontal retorts are employed they are made of cast iron, and vary in length from 8 to 10 feet, being from 28 to 34 inches wide and from 9 to 14 inches deep. The charge is introduced by an opening in the end of the retort, by which aperture the exhausted residue is removed when necessary. This aperture is closed by a tightly fitting cast iron cover while the distillation is going on. At the other end of the retort is a pipe for carrying off the products of distillation. This communicates with a larger pipe, and this latter with the condensing apparatus. A number of these retorts are set together in a row, with a furnace at one end, and flues extending beneath the retorts, while the upper parts of the retorts are covered with brickwork, to prevent the oil vapours from being decomposed by the heat of the waste furnace gas passing to the chimney through the flues above the retorts.

The gaseous products of the distillation of the tar, leaving the retort by the exit tube already described, are cooled by being made to pass through a number of iron pipes exposed to the air, or surrounded by water, and thus becoming condensed pass into a reservoir in the form of the oil, which forms the material from which the various hydrocarbons are separated by fractional distillation. Accompanying the oil vapours are certain uncondensable gases; these escape through a properly contrived outlet which is made in the condensing pipes; in some works these escaping gases are utilised as fuel, and in others for purposes of illumination.

In other works superheated steam is driven into the retorts during the process of distillation; but although this has the effect of sweeping the oil vapour more quickly out of the retort into the condenser, it is questionable whether this advantage covers the extra cost of the production of the steam.[61]

In many parts of Germany the extraction of the crude oil or tar from bituminous substances is effected in ovens. In these ovens the bituminous body is thrown upon a layer of burning fuel which covers the bottom of the oven, the result being that the bituminous matter is resolved into gaseous bodies which are lost, and tar which flows downwards toward the burning fuel, which being covered with a layer of clay is prevented from entering into violent combustion. This method, however, is only had recourse to on a small scale, since it is found that in most cases the tar obtained by means of it is not of a kind suited for yielding paraffin and paraffin oils.

The preparation of the tar or crude oil from fossil fuel, of the character already specified, constitutes one of the most delicate and difficult branches in the manufacture of paraffin oils, and paraffin, &c. The chief sources of failure to be avoided are the overheating of the oil vapour, and its consequent decomposition (varying in amount) into useless gaseous products; and its inefficient condensation.

It has been shown by Vohl that even when the construction of the retorts is not of the best, an average yield of tar may be obtained by the proper condensation of the vapours. “The complete condensation of the vapours of the tar is one of the most difficult problems the mineral oil and paraffin manufacturer has to deal with, while the means usually adopted for condensation, such as large condensing surfaces, injection of cold water, and the like, have proved ineffectual. It has often been[62]

An important condition for the safe and quiet distillation of the tar or crude oil when obtained is that it should be free from water. Unless the removal of the water is effectually accomplished, during its distillation, the tar may boil over, and coming into contact with the fire under the still may give rise to an alarming conflagration. The dehydration of the tar is effected in an apparatus constructed for the purpose, consisting of an iron tank placed within a larger tank, a space of about two inches intervening between the two tanks is filled with water, which is heated to, and kept at a temperature of between 60° and 80° C., for 10 hours, by the end of which time the ammoniacal water having separated from the lighter tar is drawn off by a stop-cock placed at the bottom of the tank, whilst the tar is decanted through a valve at the top.

In America the distillation of the natural petroleum oils is carried out in cylindrical stills capable of holding as much as 1600 gallons each. The retorts employed in the distillation of the tar or crude oils obtained from shale and other bituminous compounds are often constructed of large cast-iron flanged pans, each capable of containing from 1¹⁄₂ to 3 tons of the oil, “and forming the body of the retort. The pan is set in brickwork with flues running round the upper portion, and beneath it is a perforated dome of brickwork, through which the flame and hot gas from the furnace pass up round the bottom of the pan before entering the flues by which the upper portion of the pan is heated. To the flange of the pan is fitted a flanged cover having on one side a discharge pipe through which the vapour is passed to the worm of the condenser. In the centre of the cover is a manhole. The oil condensed in the worm is discharged through a pipe into a receiver, and the uncondensable gas escapes through an ascending pipe.”[63]

The processes to which the crude oil or tar and the natural petroleum are next submitted differ only in the degree of treatment with certain agents to which these products are subjected when, after similar methods of fractional distillation, they have been isolated from each other. The benzoline and paraffin oils (both for burning and lubricating purposes) separately yielded by the natural oils seldom require purification, or if so in a minor degree only, whilst the same bodies as obtained from the crude shale oil or tar must be submitted to various processes of depuration before they are fit for the market. Thus, the crude petroleum or burning oil derived from tar is characterised by a more or less dark colour and disagreeable smell—properties which are partly due to the presence of carbolic acid and its homologues. By agitating the paraffin oil with a solution of caustic soda these objectionable substances are removed.