melted together, and kneaded under water. By this process the fine powder is washed out, and in time sinks as a sediment in the liquid. The mineral yields not more than one-fourth of its weight of coloring material.

Up to a very recent time Italy continued to be the chief, as it had been the original, manufactory of ultramarine, and thence the finest shades were derived. The tediousness, the difficulty, and, consequently, the costliness in both time and money of the old process of producing ultramarine from the Lapis lazuli, naturally excited great desire among scientific chemists to find some cheaper and readier artificial means of producing that color, doubly precious to the painter for its beauty and its permanency; but so invariable from different. causes were the failures of all attempts in that direction that the solution of the problem was well nigh despaired of, when hope was as suddenly as accidentally revived. In 1818 it happened that in France a sandstone furnace for the melting of soda was taken down, and a beautiful colored substance, never seen there before, was discovered. It was remarked, that formerly the furnace for the melting of soda had always been constructed, not of sandstone, but of brick. The mass of matter thus discovered was examined by Vauquelin, who observed in its appearance and composition points of great resemblance with ultramarine; but still no clue offered itself to guide him through the perplexities of the investigation. Similar observations were made in other soda manufactories, as, for instance, by Hermann, in Schöubeck, who had thrown away above a hundred weight of the colored mass found in a similar furnace when the latter was pulled down; and by Kuhlmann, at Lille. We shall not venture to decide whether or not the "blue material," mentioned by Göethe in his "Italian Travels,” (1781,) as being taken from limekilns in Sicily, and used for the adornment of altars and other objects, was homogeneous with this product of the soda furnace, and whether both were, in fact, an artificially and accidentally produced ultramarine. The question still remained unanswered, how was this substance in the case of each furnace produced? In what did it originate? At length, in 1828, the solution of this important question was found and published by Professor C. Gmelin, of Tuebingen. During eighteen years he had been occupied with researches on the "Lapis lazuli" and its kindred minerals, the products of the volcanic eruptions of Vesuvius. Reflecting on the recent circumstance, he was led to believe that, notwithstanding there had been so many unsuccessful attempts, the production of an artificial ultramarine was not an impossibility. Further study of the natural coloring substance disclosed to him the sulphurous portion of the components, and holding that clue he at length succeeded in producing a most brilliant ultramarine.

At about the same time, another German chemist, the well-known “Doebereiner," had a glimpse of the true nature of the coloring principle of ultramarine. He was the first positively to assert that it was to be attributed to sulphur alone. He obtained, however, a mere glimpse of this beautiful discovery, other occupations preventing him from following it up. A very few more experiments, and he would have been completely in possession of it. Gmelin was scarcely more successful, though the absence of this additional jewel in his scientific crown was owing to a different cause. It is not in the nature of a true savant to place his talent at usury, or, in plainer terms, "to make money by it;" though now and then doubtless, in these days of extravagant projects, it is not impossible to find a savant at the head of some speculating manufactory, to the success of which his reputation gives a substantial guarantee. Men of science of this kind are certainly much sought after by industrial speculators, yet the exceptions do not greatly affect my assertion as to the general disinterestedness in this respect of the German savant.* He, for the most part, when, in the

*This characteristic is by no means confined to German savants, but is shared by most men of science in all countries.

course of his researches and experiments, a discovery has been made which may be rendered available for utilitarian purposes, forbears to make a secret of it, publishes it without reserve, and leaves the pecuniary harvest, large or small, to be reaped by others. Is this because the enthusiastic savant has so little worldly wisdom, or so exclusive a desire of reputation? Gmelin's own words may, perhaps, help the reader in forming a reply to this question. He says: "I have thus mentioned all the circumstances which must be kept in view in the manufacture of artificial ultramarine, and I have also added some hints for the use of those who may make it their object to manufacture this color on a larger scale. I have now only to desire that others in like manner may unreservedly publish their experience on the subject, so that the production of this article may, as early as possible, attain to the highest degree of perfection. We cannot, it is true, when an important technical discovery has been made, which promises large profits, fairly blame any one for keeping it a secret until he has achieved that great and justifiable aim of all mankind, security against want; but beyond this, no one has a right to maintain secrecy that he may secure gain. And it is very much to be regretted that by the withholding of so many discoveries (often buried with those who make and conceal them) science has been hindered in its progress, and an obstacle thrown in the way of the noblest object of man, that, namely, of increasing knowledge and diffusing civilization." Such, literally, was the practice of Gmelin. While at Paris, in 1827, and previous to the publication of his discovery, he unreservedly communicated his ideas on the artificial production of ultramarine to several chemists, especially to Gay Lussac. And, behold! on the 4th of February, 1828, Gay Lussac made a report to the French Academy that Guimet, at Toulouse, had succeeded in manufacturing ultramarine of all kinds. Did the discovery originate in the open and disinterested communication of Gmelin, or did it not? Who shall decide? Guimet, it is but just to say, warmly defended himself against such a suspicion; he affirms that he was prompted to his experiments by the examinations of Lapis lazuli, made by Desormes and Clement, and claims that he had produced artificial ultramarine before Gmelin's visit to Paris.

Whether the method of Guimet is essentially different from that of Gmelin cannot be determined, for, while the latter published his discoveries with every particular, Guimet, on the contrary, has kept his method a secret to the present day. In so far as profit is concerned, Guimet, it must be confessed, has maintained the advantage over Gmelin, and France over Germany; for Guimet forthwith made his discovery lucrative to himself and others. As early even as the same year, 1828, he had erected a manufactory at Paris for the production of artificial ultramarine, which he sold at two dollars and sixty-six and a half cents per pound, while the natural article was a little more than double that price. Guimet succeeded in having his product adopted for the painting of the beautiful ceilings of the museum of Charles X, and thenceforth his fortune was made. In 1834 the price had risen to from four to five and one-third dollars per pound, but in 1844 had again fallen, and ranged from two and one-sixth to two and onethird per pound, though the best quality for oil painting was still sold at six dollars and forty cents. The cheapness of the ordinary article enhanced the demand, and the product of Guimet's factory speedily rose from twenty thousand to one hundred and twenty thousand pounds, of which twenty thousand pounds were exported to foreign countries. Not only did Guimet amass immense wealth; he was the recipient also of many public honors. From the French "Society for the Encouragement of Industry" he received a premium of 5,000 francs, and medals from various French industrial exhibitions; and this as early as 1834, when the real importance of this eminent discovery could have been scarcely appreciated. In 1851, at the London exhibition, Guimet received the large gold medal.

In Germany the manufacture of ultramarine proceeded at a far slower and less profitable rate, though the directions published by Gmelin would have amply sufficed for manufacturing on a. much larger scale. He already knew that the proportions of silicious earth, natron, and potter's clay might vary to a certain extent without at all affecting the result; and he had also found that the production of artificial ultramarine requires two distinct operations, viz: 1. The production of the so-called green ultramarine; and,

2. The transmutation of the green into the blue article by roasting the former, while allowing the access of air.

This latter necessity he was taught by the accidental bursting of a crucible. His observation of this accident enabled him to master the whole process, and conduct it to any desirable issue. To the manufacture on an extensive scale, however, the condition insisted upon by Gmelin of perfect or chemical purity in the silicious earth and the potter's clay employed, continued to present an embarrassing obstacle on account of the delay and difficulty in bringing the material to that state.

It is true that he had himself raised the question whether the production of the two expensive materials, both of them being components of potter's clay, might not be dispensed with, and he experimented upon various specimens of tolerably pure clay containing the maximum of 43 per cent. of iron. But he considered the results of the experiments unsatisfactory, on account of the presence of even such a proportion of iron. From a porcelain clay containing very little iron he obtained, indeed, a very beautiful ultramarine, which he considered quite fit for oil painting, especially for landscapes. But even this product could by no means be compared to the natural and most beautiful kind. The artificial article always retained a scarcely perceptible tinge of green and gray; while the positive red, on which depends the peculiar brilliancy of the natural ultramarine, was wanting. This difference was especially noticeable when both pigments were rubbed in oil. The circumstance that Gmelin aspired to the highest excellence, and would not content himself with mere mediocrity, was an obstacle to the introduction of this article into German industry, and restricted its use when it was introduced. Still, the first German manufactory on the principle of Gmelin's process commenced working in 1834, under the management of Leverkus, of Wermelskirchen, and very soon occasioned a great change alike in the price and the popularity of the article.

In 1832, the celebrated French chemist, Dumas, in his "Manual of Chemistry," had expressed the opinion that chemical purity of materials might very well be dispensed with in the manufacture of artificial ultramarine, and that common clay might be used, provided it did not contain too much iron. Professor Engelhardt, of the Polytechnic School, Nuremberg, while translating the works of Dumas into German, was especially impressed by that statement, and was induced thereby to make new experiments, but his labors were terminated by death before he had obtained any positive and satisfactory results. His assistant and successor, Leykauf, continued the deceased professor's experiments, and was fortunate enough to succeed, where all previously had failed. By means of potter's clay, Glauber's salt, and coal, he manufactured the most beautiful ultramarine, in the renowned manufactuory of Ley Rauf, Heyne & Co., at Nuremberg; and in a very few years the firm counted its wealth by millions. Nowhere else has this branch of industry acquired such an extension; being conspicuous even among the diversified activities of Nuremberg, and justifying, therefore, a brief description in this article.

In the vicinity of the Nuremberg railroad depot, the attention of the observant traveller is pretty sure to be attracted by a stately and spacious mass of buildings of white and red sandstone. The long rows of structures, with their streets and yards, cover a space of some eighteen acres. Surrounded as the

whole is by a rampart, one might at first fancy himself to be looking upon a fortress. But the smoke from numerous tall chimneys would speedily_correct this error and betray the abode of ingenious and successful industry. It is to be regretted that visitors are rigidly excluded from the interior of this industrial hive; a useless exclusion, as the manufacture of ultramarine can no longer by any possibility be considered a secret. The visit of the King of Bavaria, in 1855, to this equally interesting and important factory, so far lifted the veil that we possess something like a reliable description, instead of the strange surmises which were previously in circulation with respect to it. On a first glance at the exterior we perceive that the vast erection has been built piecemeal, additions having been made from time to time to meet the necessities of the increasing business. It required the long period of seventeen years to render the whole what it now is- a structure heterogeneous, indeed, in appearance, but really possessing the highest conceivable adaptation to the purposes for which it was designed.

Three rows of the buildings are devoted solely to the preparation of the raw material, the motive power consisting of two steam engines conjointly possessing a thirty-eight horse-power. So various and well contrived are the stampers, crushing and sifting machines, &c., which are set in motion by these various works, that a small amount only of human labor is required to furnish abundant raw material to employ elsewhere a vast number of hands.

Groups of buildings surrounding those just mentioned contain water-works, and consist of five divisions of vaulted galleries, supported by iron pillars. Near these are the drying stoves. Close by these three principal divisions are the buildings for storing, packing, and weighing, and the clerks' offices and repairing shops. Here is a scene of continual activity, the human labor being greatly aided by a high-pressure steam engine of twenty-horse power. The communication between these various and extensive buildings is facilitated by a railroad six thousand feet, or considerably above an English mile, in length, crossing from east to west, and from north to south, and similar tram roads of timber connect the buildings in the upper stories. The iron railroad leads to the depot of the public railroad; thus placing the factory in easy and speedy communication with the principal high roads of Germany. The weight annually carried on this little railroad amounts to nearly 2,000 tons; about one-tenth of which consists of the manufactured article.

About 200 laborers are constantly employed in this establishment, and it is greatly to the credit of the proprietors, Zeltoner & Heync, that they have established a savings bank, a sick fund, and a fund for the support of widows and orphans.

We have spoken of the remarkable fall in the price of ultramarine. Competition and improved machinery and modes of operating have effected so much in that respect, that the whole price of the best article at the present time does not exceed that paid for the mere grinding, only eighteen years ago. This continual fall of price necessarily compels a corresponding expansion of the manufacture and sale to compensate for the deficit in profit. On this account scarcely a year passes without the addition of new buildings to this vast establishment. Considerably more than 5,000 tons are manufactured here yearly, at the average cost of from 25 to 37 cents per pound. The cheapness and exceeding beauty of the color cause it to be profitably and largely exported to France, in spite of the absurdly heavy import duty levied upon it there.

What we have said of this single manufactory, vast as it is, gives but a very inadequate idea of the extent and importance of the ultramarine manufacture in Germany. At the Industrial Exhibition at Munich no fewer than seven extensive manufacturers received medals, and two were honorably mentioned.

At the Parisian exhibition the French manufacturers did not dispute the excellence of the German ultramarine, or the exquisite beauty of its colors. But

they complained that it was of so many different shades that the various trades and professions which use the article were unnecessarily embarassed in the choice among so many gradations of color; for while the German manufacturers exhibited twenty different tints, the French furnished but eight. To this Germans replied, that in supplying so many different shades of the color they but complied with the public wish. Yet, nothing can be plainer than that in everything relative to color and cognate matters of taste, it is not the public which prescribes, but the artist, who elicits the artificial want. It was Phidias who created the Athenian taste for the surpassing beauty of the Phidian sculpture. Up to 1849, France had only two manufactories of ultramarine. In that year a third was added, in Alsace, (Zuber & Co., at Rixheim,) which deserves mention with that of Guimet, who still sustains his long-established reputation. To such an extent is the manufacture of paper-hangings carried on at Rixheim, that the manufacture of colors might appear a merely accessory and subordinate branch. But such is not the fact; for, besides supplying the home demand, that factory exports to a very large amount. As long ago as 1849, the establishment employed 500 laborers, at an expense of $43,333. And the motive power consisted of 44 machines, exerting, in the aggregate, a sixty.two horse power.

As mentioned above, Gmelin's mode of using only the very purest raw material has been abandoned. But, though the ultramarine manufactured on his method was undoubtedly more costly, it is no less certain that it was also far superior in color to all other sorts of ultramarine. Economical manufacture is now sought in a variety of ways. A white German clay found in many parts of the country, and known to the trade under the name of "lanzin," is the most commonly made use of. White porcelain earth is preferable on account of its greater purity. A small portion of magnesia and lime is of no conse quence; but if iron be present in greater proportion than one per cent., the utmost care is requisite to produce an even tolerable color. All foreign matters of a tangible kind are carefully removed by repeated washings; the clay is then dried, made red-hot, and reduced to a fine powder in a mill or stamper. These preparatory processes, simple as they appear to be, are in reality of great importance, and the mechanical contrivances for rendering them perfectly effective are among the most ingenious, as well as the most costly, of all the machinery employed in the manufacture. To the ground or crushed mass there are now added sulphuric natron, soda, sulphur, and coal or charcoal; the whole having been previously reduced to the finest possible powder. If coal instead of charcoal be used, such must be selected as after combustion leaves the smallest quantity of ashes. Sometimes rosin is used instead of coal, and, being decomposed by the heat, answers all the purpose of the mineral. Heated together, these various materials become fused into one mass. Upon the process thus far described, and, especially upon the exactly proper proportion of each of the materials, the result greatly depends.

With regard to one point in the procedure there is a wide difference between the French and the German manufacture. In the latter, Glauber salt or a mixture of that salt and natron is always used; in the former, only soda. The German mode is the more economical, because the sulphuric acetical natron is by the agency of the coal converted into sulphuric natrium, and thus the sulphur can be wholly or partially dispensed with if soda be added at the same ime. It is true that a somewhat greater quantity of coal will be required, but there can be no comparison between its price and that of sulphur. As to the result, it does not seem that the one or the other method is very greatly preferable.

There is great difference in the proportions of the several components of this mixture; but the following may serve as a general rule: