PREFACE. (continued 2)

COLORED GLASS.

The distinguished French chemist, M. Chevreul, who has devoted so much attention to the subject of color, has lately published a memoir on painted windows, in which there are many points which deserve the attention of artists and others who are interested in the manufacture of colored glass. It has often been much noticed that old stained glass windows have a much richer effect than modern ones, and M. Chevreul, speaking of this superiority, attributes it to what moderns regard as defects. In the first place, much of the ancient glass is of unequal thickness, and so presents convex and concave parts, which refract the light differently and produce an agreeable effect. In the next place the old colored glass is not a colorless glass, to which has been added the particular coloring material, such as protoxide of cobalt, &c. Old glass contains a good deal of oxide of iron, which colors it green, and to this must be attributed the peculiar effects of antique glass, colored by cobalt and manganese. M. Chevreul appears to think that modern stained glass is too transparent to produce the best effects. M. Regnault, the chemist, has recommended that all this kind of stained glass should be cast, to avoid the monotonous effect of plain surfaces on the light; and also that foreign substances should be mixed with the glass to diminish its transparency.

Many attempts have been made to color with ruby or other colors gas shades, so as to throw on surrounding objects the color of the glass; but in no case has the ray of light passing through colored glass, to refract the shade, been successful.

But when a ray of solar light is passed through a colorless prism, it is refracted, and forms, when thrown on a wall or screen, a broad band of colored light,—red, orange, yellow, green, blue, indigo, and violet,—which is known as the prismatic or solar spectrum.

ARTIFICIAL DIAMONDS.

We find a report in French journals that M. Gannal has succeeded in obtaining crystals, having all the property of the diamond, through the mutual reaction of phosphorus water and bisulphide of carbon upon each other for the space of fifteen weeks.

The crystals were found to be so hard that no file would act upon them. They cut glass like ordinary diamonds, and scratched the hardest steel. In brilliancy and transparency they were in no way inferior to the best jewels, and some possessed a lustre surpassing that of most real stones.

For reference we record the cost of materials for flint-glass, say in 1840 to 1845, as follows:—

Litherage, or red lead, cost 6 ½ cts. per lb.

Pearlash, 6 " "

Nitre, 6 " "

Silex, 0 ½ " "

Present price, 1864:—

Red lead, 21 cts. per lb.

Pearlash, 17 " "

Nitre, 6 " "

Silex, 0 ¾ " "

We now refer to the early introduction of the manufacture of glass into England. The English manufacturers, like ourselves, had to struggle with the various evils incident to the introduction of a new art. France and Germany, from their long experience in the making of glass, were enabled for a long time to undersell the English manufacturer in his own market.

To foster and protect this branch of national industry, the English government imposed a heavy tax on all foreign glass imported into their dominions. This measure secured to the English manufacturer the entire trade, both with their colonies and with the home market, thus giving such substantial encouragement to the enterprise, that, in a few years, the manufacture was so much increased as to admit of exportation.

To stimulate the exportation of various articles of English production, the government, in the latter part of the eighteenth century, granted bounties, from time to time, on linens, printed cottons, glass, &c, &c. Until the bounty on glass was allowed, the exportation of glass from England to foreign countries was very limited; for the French and Germans, as has before been stated, for various reasons could undersell the English; but the government bounty changed the aspect of affairs, and shortly the English manufacturers not only competed with the Germans and French for the foreign market, but actually excluded them from any participation,—the government bounty being equal to one half the actual cost of the glass exported.

An Act of Parliament levied on flint-glass an excise duty of ninety-eight shillings sterling on all glass made in England, which excise was paid by the manufacturer, being about twenty-five cents per pound weight, without regard to quality; but if such glass was exported, the excise officer repaid the tax which it was presumed the manufacturers had paid, and a clear bounty of twenty-one shillings sterling was paid by the government to the exporter on each hundred weight of flint-glass shipped from England, being equal to five cents per pound. Under such encouragement the export increased from year to year to a very great extent, so that the excise duty of ninety-eight shillings sterling on the amount consumed at home did not equal the amount paid out in bounty. In the year 1812, fifty-second George III., an Act was passed reducing the excise duty to forty-nine shillings, and the export bounty to ten shillings sixpence. In 1815 the Act was renewed, and again in 1816. In 1825, sixth George IV. chap. 117, an Act was passed revising the former as to the mode of levying the excise duty and bounty, so as to prevent frauds on the revenue, which had hitherto been practised to a very great extent. This act remained in force until the Premiership of Sir Robert Peel, when both excise and bounty were abrogated, and the English manufacture stands on the same footing in foreign countries as those of other nations. By the protecting hand of the English government the flint-glass manufactories multiplied with very great rapidity, underselling all other nations, and not only rivalling, but far excelling them in the beauty, brilliancy, and density of the articles manufactured.

The greatest stimulus ever given to the glass manufacture of England was the abolition of the duty on it in 1845. That abolition has produced a somewhat paradoxical result. While the quantity of glass made has increased in the proportion of three to one, the number of manufacturing firms has diminished in the proportion of one to two. In 1844 there were fourteen companies engaged in the manufacture. In 1846 and 1847, following the repeal of the duty, the number had increased to twenty-four. The glass trade, after the removal of the heavy burden imposed upon it, seemed to offer a fair opening for money seeking investment. The demand for glass was so great that the manufacturers were in despair. Glass-houses sprang up like mushrooms. Joint-stock companies were established to satisfy the universal craving for window-panes. And what was the result? Of the four-and-twenty companies existing in the year 1847, there were left, in 1854, but ten. At this time there are but seven in the whole United Kingdom. Two established in Ireland have ceased to exist. In Scotland, the Dumbarton Works, once famous, were closed in 1831, by the death of one of the partners, afterwards reopened, and again closed. The seven now existing are all English.

The manufacture of the finer kinds of glass was introduced into England not many years ago from Germany, and German operatives were employed at very high wages. We understand that the English glass is now superior to the German.

There is only one plate-glass factory in the United States. It was commenced only two years ago near New York, and we understand that it has met with encouraging success.

Soon after the introduction of the business into this country, a very great improvement in the mode of manufacture was introduced. Pallat, in his admirable work on glass, alludes to the American invention in only a few words, and passes it by as of but slight importance; but it has brought about a very great change, and is destined to exert a still greater; in fact, it has revolutionized the whole system of the flint-glass manufacture, simply by mould machines for the purpose of pressing glass into any form. It is well known that glass in its melted state is not in the least degree malleable, but its ductility is next to that of gold, and by steady pressure it can be forced into any shape. The writer has in his possession the first tumbler made by machinery in this or any other country. Great improvement has of course taken place in the machinery, insomuch that articles now turned out by this process so closely resemble cut-glass that the practised eye only can detect the difference. Still, the entire field of improvement is not occupied, and greater advances will yet be made. The tendency, in this particular, has been so to reduce the cost of glass that it has multiplied the consumption at least tenfold; and there can be no reasonable doubt but that, at this period, a much larger quantity of flint-glass is made in this country than in England. The materials composing glass are all of native production, and may be considered as from the earth. The pig lead used is all obtained from the mines in the Western States; ashes from various sources in other States; and silex is also indigenous. The materials consumed yearly, in the manufacture, are something near the following estimate:—

Coal, for fuel, 48,000 tons;

Silex, 6,500 "

Ash, Nitre, &c. 2,500 "

Lead, 3,800 "

for the flint manufacture. How much more is consumed by the window-glass manufacturers, the writer is without data to determine.

We have recorded the progress of improvement in the manufacture of glass, and now, relevant to the subject, we propose to examine the various improvements in working furnaces and glass-houses. To this end we present to our readers the drawing of a furnace for flint-glass,[1] with the interior of a glass-house as used by the Venetians, at the highest point of the art, in the sixteenth century.

[1]

See drawing No. 1, at end of book.

The workmen in glass will see, that, as compared with the factories of the present day, the Venetians in their instrumentalities were subjected to many difficulties,—they were oppressed by the furnace smoke, and in no way protected from the heat of the furnace, or enabled to breathe fresh atmospheric air; in fact, the impression prevailed in those days that the external air, drawn into the glass-house, was detrimental to the business, and therefore it was most cautiously guarded against.

The drawing is taken from an ancient work on glass, and although limited in the view, shows the general plan. The factory wall was conical, and rose like a large chimney, with a few windows for the admission of light. Exposed to the heat of the summer sun of Venice, and of the furnace within, neither the comfort nor health of the workman was secured. The construction of the annealing department shows two tiers of pans, the use of which must have been attended with great loss of materials. Yet, with all the perceptible inconvenience, no material change in construction was made for centuries. The same plan was adopted in France and England, and it is only within the present century that any change has taken place in the latter country. In fact, in the year 1827 an Englishman erected a glass factory on the same plan in the vicinity of New York, which, from its defective construction for this climate, soon passed out of use.

The Germans, however, departed from the Venetian plan so far as to place the furnace in a large and well-ventilated building, but without a furnace-cone to carry off the heat and smoke; still a decided improvement was thus effected over the system in use in France and England.

The plan referred to shows to the practical workmen of the present day the excessive waste of fuel arising from the construction of the furnace; for the same expenditure of fuel in the American furnace would melt ten times the material produced from the Venetian.

It is admitted that the American glass-house is far in advance of the European ones at the present day, in the particulars of capacity, ventilation, comfort of the workmen, and economy in fuel. An impression is very prevalent that glass-making is an unhealthy occupation. It may have been thus in former times; but, as a matter of fact, no mechanical employment is more healthy. Dissipated as glass-makers have been in former days, and careless of their health as they are at present, no better evidence can be adduced to prove the generally healthy character of the employment than the fact that the Glass Manufacturing Company in Sandwich, averaging in their employment three hundred hands, had not a man sick through the influence of the employment, or one die in their connection, for the space of twenty years.

Drawing No. 2[2] represents the plan adopted in the French flint-glass furnaces. These at one period were worked by noblemen only,—the labor of the furnace-tender and taker-in being performed by servants, as before stated. The apparel and general style of dress, as indicated by the drawing, shows that more attention was paid to the fashion of the day than to comfort. The form of the furnace being similar to the Venetian shows it to have been subject to the same unnecessary waste of fuel; but it would appear that the French manufacturers had taken one step towards improvement, in using the waste fuel of the furnace to anneal their glass. The Venetians had a separate furnace to anneal their glass, supported by independent fires, as used at the present day.

[2]

See drawing No. 2, at end of book.

The place marked D, over the crown of the furnace, is the door of the annealing oven; but the drawing is so imperfect that the artist does not show by what flues the smoke escapes, or in what way the glass was drawn from the annealing oven; for only the external view of the furnace is given. But it is fair to presume that the plan was the same as still exists in France, and as adopted by a French company now working a flint-glass factory in Williamsburg, near New York; viz.,—the taker-in, so called, mounts by steps to door D and places the articles in iron pans, which are slowly drawn over the furnace and through another door on the opposite side, to allow the glass vessels to cool gradually. The use of this plan is sustained by writers who describe the tools used to carry the glass articles into the upper oven to cool. In connection with the drawings of the ancient glass-furnaces, we deem it proper to give a drawing of glass-makers' tools[3] in use at that period, so that the glass-makers of the present day may observe with what instruments their noble predecessors in the art performed their labor.

[3]

See drawing No. 3, at end of book.

In many of these tools we perceive the same general characters as mark those in use now. In some, improvements have been effected; while others are quite obsolete. It is quite curious to observe the etymology of many of the technical terms of the art in use at the present day. The name of the present polished iron table, i.e. the MARVER, is derived from the practice of the Italians and French in using slabs of polished marble. The iron now called the punty, from the Italian ponteglo. The tool now called percellas, from the word porcello. In fact, nearly all the technical terms in the glass manufacture, appertaining to the tool or furnace, are derived from the Italian. By referring to the drawing, we see that the tool marked A is the blow-iron, that marked B the punty-iron. Their character plainly indicates that the work made on them must have been confined to small or light articles. C, the scissors, D, the shears, correspond to those used at the present day. The tool marked E was used to finish part of their work. F and G were their large and small ladles,—the small used to take off the then called alkalic salt, showing that they were troubled with an excess of this in their time. The shovel, then called stockle, marked H, was used to carry glass articles to the annealing oven, forks not being then in use. The crooked iron I was used to stir up the metal in the pots. The tool L was used to form or hold large articles, their punty-iron not having sufficient strength. The tool M was used to carry flat articles to the annealing ovens. The tool N was used in refining their alkalic salts, and served to take off the salt as crystallized in course of its manufacture.

The workmen of the present day will see that, as before remarked, many tools are not altered in form, while in others there is a decided improvement,—in none more than in the tool E. Tool D is exactly like those now in use; but many new tools have been introduced since that period, rendering most of the old tools useless. Improvements in the form of glass-furnaces, construction of the glass-house, tools, &c., have been very gradual,—more so, in fact, than in almost any other art, when we consider that a period of about four hundred years has elapsed since the furnaces, tools, &c., herein referred to, were in use, and that they remained very much the same until the present century. It is indeed no undue arrogance of claim to say that the very many improvements in furnaces, working machinery, tools, &c. (such as enable the manufacturer here to melt with the same fuel double the quantity of glass that can at present be done in the European furnaces,) are entirely owing to the progress of the art in this country. By the perfection of our machines double the product can be obtained; and although the glass maker is paid at least three times the wages usually paid in Germany or France, we can, in all the articles where the value of the materials predominates, compete successfully with importers of foreign glass; but when the labor on glass constitutes its chief value, then glass can be imported cheaper than it can be manufactured in this country. Essentially, however, we may say, in the realm of art as in that of civilization and progress,—

"Westward the star of empire takes its way."

PRESSED GLASS.

This important branch of glass-making demands more than a passing notice. Although it is commonly believed here that the invention originated in this country, the claim cannot be fully sustained. Fifty years back the writer imported from Holland salts made by being pressed in metallic moulds, and from England glass candlesticks and table centre-bowls, plain, with pressed square feet, rudely made, somewhat after the present mode of moulding glass. From 1814 to 1838, no improvement was made in Europe in this process, which was confined to common salts and square feet.

America can claim the credit of great improvements in the needful machinery which has advanced the art to its present perfection. More than three quarters of the weekly melt is now worked up into pressed glass, and it is estimated that upwards of two million dollars has been expended in the moulds and machines now used in this particular branch of glass-making. This leaves Europe far behind us in this respect. With us there is active competition for excellence. It is, however, conceded that James B. Lyon & Co., of Pittsburg, stand first. To such a degree of delicacy and fineness have they carried their manufacture, that only experts in the trade can distinguish between their straw stem wines, and other light and beautiful articles made in moulds, and those blown by the most skilled workmen. When we consider the difference in the cost between pressed and blown ware, this rivalry in beauty of the former with the latter becomes all the more important to the public, as it cheapens one of the staple necessaries of civilized life.

Great credit therefore is due this firm for their success in overcoming difficulties well understood by glass-makers, and doing away with the prejudice of the skilled blowers, who naturally were not inclined to put the new and more mechanical process of manufacturing glass on a par with the handicraft of the old. Lyon & Co. also excel all other American firms in large ware for table services, as well as in the more delicate objects of use.

In speaking of the improvements in glass-making in America, we must not overlook what has been done by the New England Glass Company.

Convinced of the importance of scientific skill in their business, they secured some years ago the services of Mr. Leighton and his three sons, at a liberal compensation. Besides possessing the best practical knowledge, they had also artistic taste, which enabled them to give elegant finish to their workmanship, and to introduce new and more beautiful patterns into it.

They did not neglect, however, the more homely but useful articles; but executed orders for large and heavy objects for druggists' and chemical wares and philosophical apparatus, so satisfactorily as to secure a monopoly in them. Their richly cut, gilded, colored, and ornamental glass is considered equal to European work.

John L. Gillerland, late of the Brooklyn Glass-Works, is remarkably skilful in mixing metal. He has succeeded in producing the most brilliant glass of refractory power, which is so difficult to obtain. A gold medal was awarded his glass, in face of European competition, at the Great International Exhibition in London, 1852. In making rich glass, the gaffer or foreman must understand the science of chemistry sufficiently well to mix and purify his materials in the best possible manner, removing all crude or foreign matter, and combining the proper substances into a homogeneous mass. Without this practical experience and knowledge, his glass, instead of being clear and brilliant, and of uniform color, will be dull, and of many hues or shades. It is important also that his personal character be such as to command the respect of the workmen.

LENSES.

Optical glasses have engaged the attention and investigation of scientific men for centuries. We read of the wonderful exploits of the burning lens of Archimedes, and find the remains of lenses thousands of years old in the ruins of Nineveh, Babylon, and Pompeii. They are of the utmost importance in the science of astronomy. The slow progress made in perfecting them shows the inherent difficulties that exist in obtaining glass of the required purity. One of these is the different specific gravities of the material used. Hence the lower part of a pot of melted glass is of greater specific gravity than the top, causing a tendency to cords or threads, an evil which science has yet to learn to overcome. Not even the large bounty offered by the English Government and the Board of Longitude has been successful in effecting any important improvement in this branch of manufacture. Munich enjoys the reputation of producing the best lenses, and consequently the finest telescopes. Sir Isaac Newton, Gregory, Dolland, Keir, and others adopted lenses made from flint- and from crown-glass, it being necessary to use both in the construction of achromatic telescopes, one possessing as small and the other as great dispersive powers relative to the mean refractive powers as can be procured. But the inherent defect of the lenses still remained. M. Macquer remarks, "The correction of this fault appears therefore to be very difficult." He had tried in vain to remove it by very long fusion and fierce fire. Others have found this by experience not to correct, but to augment the evil. Mr. Keir is of opinion that some new composition must be discovered, which, along with a sufficient refractive power, shall possess a greater uniformity of texture.

Since then, it is certain some improvement has been made in the composition for lenses. In an English paper we find the following:—"One of the most remarkable optical lenses of modern manufacture is that produced by Messrs. Chance, English manufacturers, being an attempt by them to improve the manufacture of glass for optical purposes. The diameter is twenty-nine inches, and it is two inches and a quarter thick. It is really not a lens, but a plain disk intended for a lens, should its quality be sufficiently fine. The weight is about two hundred pounds. This piece of glass was inspected, on its first public exhibition, by eminent scientific judges. It was by them examined edgewise, transversely, and obliquely; it was viewed by daylight and by candle-light; it was tested by the polariscope and by other means; and after having been thus subjected to a severe ordeal, it was pronounced to be the largest and finest known specimen of the kind."

The promise held out by the foregoing we fear has failed, as in very many previous cases, or the world ere this time would have heard of its success. An achromatic object-glass for telescopes consists of at least two lenses, the one made of flint-glass, and the other of crown-glass. The former, possessing least power of dispersing the colored rays relative to its mean refractive power, must be of greater value than the latter. It is upon this principle that the achromatism of the image is produced, the different colored rays being united into one focus. Flint-glass, to be fit for this delicate purpose, must be perfectly homogeneous, of uniform density throughout its substance, and free from wavy veins or cords.

From the foregoing, the reader will see that, as has been said, the chief difficulty which exists in making telescopic lenses arises from want of pure glass. Every attempt to correct this evil has failed; it is well known our best telescopes and like optical instruments have always achromatic lenses, and for photographic purposes achromatic lenses are indispensable. If philosophers and astronomers have with so imperfect lenses attained so much, what may not the astronomer look for when science gives him lenses made from pure glass? If the heavens, by imperfect instruments, have so far been unveiled, to what extent may he not then be able to penetrate the pure ether, and reveal planets and heavenly bodies as yet unknown?

We close our reminiscences of Glass and its manufacture, by presenting to our readers a view of an American model glass factory of the present day.[4] By comparing this view with the sketches heretofore given of the early Venetian and French factories, they will perceive the very great improvement which is apparent over the ancient plans, an improvement conducing alike to the health and comfort of the workmen. Thirty years have passed in its development, during which many difficulties arose from the conflicting opinions of the English and German glass-makers; and, in fact, it was not until the proprietors boldly separated themselves from the current and influence of old, and almost fixed opinions, that any decided progress was shown in the development of manufacturing efficiency, or any plan contributing to the health and comfort of the workmen employed.

[4]

See drawing No. 4, at end of book.

It is to be borne in mind that the first glass works in this country were established by the Germans, who used no other fuel than wood, the furnaces for window-glass constructed under their directions being for that fuel only; on the other hand, the English workmen who introduced the making of flint-glass had made use of no other fuel than coal, and the English were therefore obliged to adopt (for the want of coal) the German plan for furnaces, and adapt the same to the making of flint-glass. The house was like the furnace, half English and half German, and from the year 1812, for thirty years, little or no improvement was made in this particular. Year after year the old plan was followed, until necessity paved the way for new plans in the effort to secure a less expensive mode of melting glass.

The result has been highly favorable. More than one half has been saved in the melt, annealing leers, and working places, yielding the workmen greater space and facilities in performing their work, and no longer exposing them to the discomfort of extra heat, smoke, and unhealthy gases. These improvements have enabled the American manufacturer to sustain his business in the severe and trying competition with foreign manufacturers, who forced their glass into this country through their agents a few years since, in such quantities, and at such reduced prices, as seriously to affect the prosperity of our artisans; yet, aided as they have been by a tariff directly promoting foreign interest, and by the very low rates of wages paid on the Continent, they have been successfully contended with, and now a home competition has sprung up, reducing prices below a fair standard,—a competition, the result of enterprise, which will, erelong, regulate itself, for we fully hold to the maxim, that competition, honest and well sustained, is the soul and life of business:—

There is no mechanical employment in this country yielding so good returns to the industrious as a good worker in glass, of the present day, can secure in the exercise of his skill. And we may still further say that there is no mechanical branch of industry offering such advantages for the full manifestation of a workman's real skill and industry, if the conventional usages which restrict the work could but be abrogated,—usages tending to a limited amount of work, and consequently making the workman to realize but a limited amount per week. Such workmen, of all others, should be allowed the inherent and inalienable right to work as long, and at such times, as the individual may deem for his comfort and interest.

We have expressed the opinion that the manufacture of glass is as yet but in its infancy. The experience of every day confirms the assertion, and illustrates the maxim that "life is short, art is long."

The time is not far distant when this country will become, we think, the largest exporter of glass, and the manufacture compose a most important item in every assorted export cargo. In this connection a hint to ship-owners may not be amiss. It is well known that in England, when a ship is put up for a foreign port, it is the custom to rate the freight according to the value of the merchandise,—dry goods paying the highest freight, hardware the next highest, earthen and glass ware the lowest. If our merchants would adopt this plan, very many of our bulky manufactures would find a market abroad; when, however, the same rate is required for a cask of glass ware as for a case of silks or prints, it taxes the latter a small percentage, but practically vetoes the export of the glass.

Our task is now ended; our object has been to give a simple and succinct outline of the characteristics and progress of the Glass Manufacture, to suggest such hints as might bear upon the further advance of the art, and the preservation of those practically identified with the manufacture, and, if possible, to attract the attention of those hitherto unacquainted with its nature and history. If we have neglected the maxim that "those who live in glass houses," &c., it has not been from the want of honest endeavors to remember it; and if we have contributed either to the instruction or the pleasure of any reader, (and this is our hope,) we shall not regret the hours spent in the preparation of this little work.