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On being heated in powder in a porcelain crucible, over a spirit lamp, it turns gray for a moment, emits a faint smell of organic matter, but none of ammonia,* and loses 10 p. c. in weight.

It consists of not far from 80 p. c. of phosphate of lime, and 10 p. c. of water; while the remainder is made up of a little insoluble matter, carbonate of lime, sulphate of lime, sulphate of soda, and traces of chlorid of sodium and fluorine.

The trap rock is often found intermingled with the mineral in fragments many inches in diameter. It has the characteristic fracture and color of this rock; but when examined more nearly, it is found to contain but little feldspar, being almost wholly composed of a dark green pyroxenic mineral, nearly allied to bronzite or schiller spar. The phosphate is completely fused where in contact with the trap; and occasionally the mixture between the two, is that of a brecciated mass.

The name of the species has allusion to its property of flying to pieces, when heated.

4. Glaubapatite.

Crystals small, tabular, in druses, forming botryoidal and stalactitic masses: columnar, fibres somewhat flattened and radiating from the centre of little oval masses and stalactites. Color, pale yellowish or greenish brown. Translucent. H.-3.5. Gr.=2.6. Also massive, with a conchoidal fracture and of a dark chocolate brown color, to nearly black. Brittle.

When heated in a glass tube, gives water, at the same time turning brown and evolving a slight organic odor. Before the blowpipe it does not decrepitate, but turns brown on the first impression of the heat, and quickly fuses with ebullition, coloring the flame yellow, with a very distinct tinge of green around the heated mass. It finally yields a semi-transparent glass. With borax, melts into a colorless glass. When powdered, the mineral dissolves without effervescence, in hydrochloric and in nitric acid, affording solutions of a porter-brown color, from which ammonia throws down the same precipitate as in pyroclasite. Analysis gave the following result:

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It occurs abundantly in irregular corroded, drusy shaped masses, (but very rarely crystalline) often coated on one side with pyroclasite; and sometimes, the two species are intimately blended together. It is named out of regard to its relationship to apatite and to glauber's salt.

* Even when heated with caustic potash or lime.

5. Epiglaubite.

In small aggregates, or interlaced masses of minute semi-transparent crystals of a shining vitreous lustre, which are always implanted upon druses of glaubapatite. H. = about 2.5.

Yields abundance of water when heated in a close tube. Insoluble in water, until after addition of hydrochlyric acid, when it disappears without effervescence. Melts easily into a semi-transparent colorless glass tinging the flame green. It is a largely hydrated phosphate, chiefly of lime. It may also contain magnesia and soda; but at present the quantity in my possession is too small to determine more accurately its composition. It would appear to be rare at the locality.

It is named from its position, upon the previously described species.

ART. XI.-Correspondence of M. Jerome Nicklès, dated Paris, April 26th, 1856.

Report on the history of the manufacture of Artificial Soda.-The question of priority as to the process of manufacturing artificial soda has just been the subject of thorough investigation by the Academy of Sciences. This work was called forth by the Minister of Public Instruction at the request of the children of Leblanc, author of the process which bears his name. Another claim, that of the children of Dizé, collaborator of Leblanc, being presented at the same time, the Section of Chemistry in the Academy of Sciences was obliged to proceed to a historical and bibliographical research which has resulted in a complete elucidation by M. Dumas of this important point in the history of Science.

The discovery of the process which derives soda from marine salt was made by Leblanc, who was also the first to give it a trial. It was not till afterward that he associated himself with Dizé, then chemical assistant at the College of France.

Nicholas Leblanc was born in 1743. Toward 1780 he was attached as surgeon to the household of the Duke of Orleans. He commenced in 1785 his communications upon crystallization which gave him a distinguished rank among the chemists of the time. His first researches upon methods of obtaining soda economically, date from 1784. This problem had already been broached, and different processes had been proposed for making soda from marine salt either by means of lime, or by means of the oxyd of lead, but without industrial results.

In 1777, Father Malherbe, a Benedictine, pointed out a process of converting marine salt first into sulphate of soda which he afterwards decomposed by means of charcoal and iron; a process which has quite lately been put in practice by Mr. E. Kopp, as has been already mentioned in this Journal.*

In 1789, De la Métherie proposed to convert marine salt into sulphate of soda, and to reduce this sulphate by carbon. This reduction would

* Corr. of J. Nicklès, Nov. 1, 1855.

only have given sulphuret of sodium. Leblanc was aware of this, and according to Dizé, trials were made by himself and Leblanc to decompose this sulphuret by means of carbonic acid. This process, taken up by Pelletan in 1827, became the basis for establishing a manufactory in Paris; but the enterprise was not successful, and up to this time the method is not employed.

These processes were brought forward in consequence of competition for a prize offered by the old Academy of Sciences to the best work on the fabrication of soda from marine salt. The object was to protect the arts of bleaching, glass-making and soap-making against the evil effects of a rise in the price of pearlashes produced by the Revolutionary War in the United States, and also a rise in the native sodas of Spain, and the scarcity of beds of native natron. The prize was not awarded. The production of artificial soda, like so many other inventions, was to be accomplished only after obstinate trials, the theory of which was not to precede the results. It was not foreseen that in calcining the sulphate of soda with chalk and charcoal, an insoluble oxysulphuret would be obtained containing all the sulphur, and capable of yielding to water all the carbonate of soda contained in the product.

This is the discovery of Leblanc. It belongs entirely to him as M. Dumas has established by means of written documents of incontestable authenticity, from which it appears that on the 12th February, 1790, there was formed before a notary a company for carrying out the inven tion, a company composed of M. Leblanc, Dizé, and as loaner of the funds, the Duke of Orleans.

To the fabrication of artificial soda, the making of sal ammoniac, and of white lead were added, processes of which Dizé was the author.

The Company was established at St. Denis near Paris, in a factory called Franciade, and the manufacture commenced but without much success. The events of the Revolution soon caused the sequestration of the property of the Duke of Orleans and consequently that of the soda factory in which he was the capitalist.

At the same time, upon the proposition of a member of the national convention, Citizen Carny, possessor of a process for the extraction of soda, an appeal was made to all Frenchmen to make within three months a surrender of their private interests and to deposit upon the altar of their country the processes which would allow the manufacture of soda from a product drawn from French soil and which would thus relieve the country from the tax paid abroad.

Twelve processes were sent to the Committee of Public Safety, that of Leblanc among them. It was recognized as the best, and the Convention ordered the publication of his brevet d'invention taken in 1791, but acknowledging his rights to a fair indemnity which the misfortunes of the time did not allow to be paid. The hour of reparation has at last arrived. The section of Chemistry in the Academy has decided as follows:

"1. The important discovery of the process by which soda is extracted from marine salt belongs wholly to Leblanc.

"2. Dizé made researches in common with Leblanc only for the purpose of determining the best proportions of the materials to be employed in the manufacture of soda, and for establishing the factory at St. Denis.

"3. If then it is proposed to render just homage to the author of the discovery, it is due to the memory of Leblanc, and to his family should

the testimonial be addressed."

Leblanc was the type of the inventor; full of self denial, perseverance, confidence. His correspondence shows that he left no step untried, that might secure the success of his work. His savings, the fruit of labors undertaken from day to day, were all consecrated to this grand object; and when reduced to extremities, he exhausted every resource.

At several times the Government sent him money, to encourage his researches, and on the 19 Fructidor an II. (1793) he obtained 4000 livres from the Committee of Public Safety to meet the advances he had made in reference to the project of which he was the inventor. Leblanc was a man both of imagination and knowledge. The most distinguished men of his times professed for him a warm sympathy. He took part in all those liberal associations where friends of science resorted. The government charged him with various scientific missions. He published various researches upon nickel, alum, sulphate of magnesia, the production and extraction of saltpetre, the chemical preparation of manures, &c., but he never realized the dream of his life. In despair, he destroyed himself on the 15th of January, 1806. He left two sons, one of whom, a professor in the Conservatoire of Arts and Trades, has acquired a high reputation in the industrial world by his publications and the progress which he has made in the invention of machines.

Manufacture of Chinese Porcelain.-In presenting to the Academy of Sciences the important work of M. Stanislas Julien on Chinese porcelain, a work mentioned in my last communication, M. Chevreul gave a brief review of its contents.

The art of making porcelain has been carried back to an exaggerated antiquity. It is now demonstrated that the earliest porcelains were made in China at an epoch between 185 B. C. and 87 A. D. The porcelain vases found in the tombs of Egypt are not of the antiquity attributed to them. M. Julien has contributed not a little to correct this error.

The Chinese author passes in review, according to the order of time and place of fabrication, the different porcelains most renowned in China. A chart of that empire indicates the location of the ancient and modern manufactures, adding much to the interest of the text. The idea of this is due to the learned translator. The processes of manufacture are described with clearness and method, and fourteen plates are reproduced from the original work. Finally the very precise notes of M. Salvétat, dissipate the doubt in which the text might leave the reader.

The interest of the book is not limited to an exhibition of the manufacture of Chinese porcelain, for M. Julien, in annexing to his translation from the Chinese a translation of the Art of making Japanese Porcelain, has done all which depended on him to render his book useful to those who consult the book from an interest in the history of the art or in the ceramic industry.

M. Julien has also given the means of comparing the processes of China and Japan with those of Europe; a task entrusted to M. Salvétat. The analogies and differences of manufacture could not be shown with more clearness than is here done by the skillful chemist of Sèvres. The

Chinese paste, like the European, is composed of a variable mixture of kaolin, that is of a material infusible in the heat of the porcelain furnace, and of material which is fusible; the glazing is of fusible material. This is the analogy. The difference is that the fusible material mixed with the composition in China is flint, but at Sèvres it is composed of sandy matter coming from the washing of kaolin and chalk. The glazing of Chinese porcelain is flint mixed with lime and frequently with frit. The glazing at Sèvres is of pure flint. The porcelain of China is less resistant to fire than that of Sèvres. The Chinese do not, like the Japanese and Europeans, apply the glazing to the biscuit. There are other differences in the application of the coloring matters and in the composition of some of the varieties. The typography of this work does honor in every respect to M. Mallet-Bachelier.

Peculiar arrangement of a Voltaic Battery.-This battery is designed for medicinal uses. It has been contrived by a constructor at Paris, M. Breton, and is maintained in a state of constant moisture with chlorid of calcium. For one of the poles there is a mixture of copper filings with saw-dust, the latter designed to separate the metallic particles,—the filings are mixed with a solution of chlorid of calcium. The other pole is a similar mixture in which the copper is replaced by zinc filings. These two preparations placed in a vase and separated by a porous cell, make a battery which has always the same intensity of action on account of its constant humidity and the indefinite number of its elements.

The natural state of Hippuric Acid. So great differences exist in regard to the proportions of hippuric acid contained in the normal state in the urine of the horse, that a chemist, M. Roussin, has undertaken to find out whether these differences are those of calculation or are really well founded. After numerous determinations, he has recognized the fact that the proportions of hippuric acid vary like the urea according as the horse is at work or rest. The following table contains the results of the trials. The urea has been determined in the condition of dry nitrate.

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Hence it is clear that horses fatigued produce much hippuric acid and comparatively little urea. Horses well fed and quiet produce little or no hippuric acid. Urea on the contrary is found in their urine in very large proportions. Its limpidity may be the index. If the liquid is clear and deposits little carbonate of lime it has much urea and little hippuric acid; if it is muddy, it is certain that there is much hippuric acid. Respiratory activity and the employment of muscular force accordingly seem to transform urea into hippuric acid. Rest, on the contrary, leaves the urea intact, and does not appear to favor its transformation into hippuric acid.

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