wet bagasse. For dryer fuels furnishing less vapor, the mixing chamber should be proportionably increased in size to supply the defficiency with air and to effect complete combustion. Rules more precise would be inconsistent with the nature of the subject.

A large and hot fire should always be preserved in the fire chamber below the grate, and directly under the charge of wet fuel, for the purpose of driving the vapor out of it and charring its lower portion-and the grate is left much more open than in furnaces for burning dry fuel of the same size, for the purpose of allowing the charred portions of the wet charge to fall through to supply fuel for this fire as fast as it becomes fit for that purpose, thus consuming the mass with little or no expenditure of other fuel.

What I claim as my improvement in furnaces for burning bagasse and and other fuels too wet to be conveniently burned in the usual way and well known ways is:

First, the combination of two chambers, the one above the other, and separated by a grate, the lower one for the combustion of any known dry carbonaceous fuel, and the upper one in immediate proximity therewith to receive heat therefrom for heating and drying the charge of wet fuel, with a mixing chamber, into which both continuously and simultaneously discharge their gases before reaching the thing to be heated, for mingling and mutual combustion.

I also claim in combination with said fire chamber and wet fuel chamber or drying chamber making the grate upon which the wet charge rests sufficiently open to allow the lower portion of the wet charge as it becomes dried and charred to fall through into the fire chamber and keep a hot fire therein, supplying the place of other dry fuel, while the uncharred portions of the wet fuel is properly supported by the grate till dried as described.

I also claim placing the mixing chamber of combustion in substantially the same position described relatively to the fire, and the wet charge, so that the products of combustion from the dry fuel may pass along the lower part of the wet charge, drying and charring it on their way to the mixing chamber, and reach it without being in any considerable degree obstructed or cooled by the wet charge substantially as shown. I wish it distinctly understood that I make no claim to any of the parts or combination above specified except in their application to the preparation and combustion of wet fuels."

It will be observed that in this mode of combustion the wet fuel is subject to a constant process of distillation by the fire in the ash pit. The products of this distillation react on each other in the mixing chamber in the manner already described, while at the same time a portion of watery vapor is decomposed in the ash pit.

Theoretically no more heat can be generated in this mode of combustion than is consumed in the transformation of water into steam and the conversion of fixed into volatile products. But it is by no means a matter of indifference whether the oxygen requisite for complete combustion is drawn from the atmosphere or is derived from the decomposition of water by carbon

and its oxyd. In the former case, not only is there a great loss of heat carried away by the inefficient nitrogen of the air, but the diluted oxygen can never produce so intense a heat with the carbon as is the result of the reaction of the nascent oxygen with that element. Although Mr. Thompson was no chemist, he did not fail with his natural acumen to perceive this advantage and in his earliest patent he remarks: "After ample experiments I have discovered that any results that can be produced, by the use of dry fuel are inferior (to those obtained from my process) in proportion to the quantity used, and that results like mine can only be obtained by the use of wet fuel * * * fed into an intensely heated chamber: under such circumstances the water in the fuel in presence of the carbonaceous substances in the furnace will be decomposed, giving its oxygen to the carbonaceous matter, dispensing with a draft and its cooling and wastful influence and rendering the combustion so perfect that no smoke is visible."

Although this mode of combustion of wet fuel is now in use on many sugar plantations in Louisiana, and in some Tanneries of Pennsylvania and New York, no notice of it has so far as I am aware appeared in the scientific Journals. I am not without personal experience of its operation on a large scale, having in 1857 enjoyed the opportunity of studying carefully the management of one of Thompson's furnaces in three compartments (similar to Figs. 1 and 2) built for the combustion of wet peat. That fuel contained over seventy-five per cent of its whole weight of water and was too wet for the best results. But with the use of one-fourth part of dry wood, even this extremely wet and otherwise valueless fuel was rendered efficient, three cords (of 128 cubic feet) of wet peat and one cord of dry wood doing the work of four cords of dry wood in driving a steam boiler.

ART. XXVI.-Note on a case of Artificial Crystallization of Metallic Copper and Dinoxyd of Copper; by J. W. MALLET.

A FLASK, in which nitric oxyd had been prepared from nitric acid and scraps of copper, was allowed to remain over night by the pneumatic trough-the end of the gas-delivering tube dipping under the surface of the water. On the next day several scraps of copper were observed dotted over with very minute but brilliant crystals of metallic copper, which under the microscope proved to be octahedrons and combinations of the octahedron with the cube and dodecahedron, of various sizes-the largest measuring about twelve-hundredths of a millimeter along an octahedral edge. Along with these crystals of copper there were little cubes of the dinoxyd of copper in great abundance

the latter not more than two or three hundredths of a millimeter on the edge, translucent, and of a splendid garnet red color.

On examination it became evident that these two bodies had been deposited in the crystalline state in consequence of the formation of the so-called " Bucholzian circuit "-one solid and two liquids so arranged as to produce electric action. As the flask cooled down the water from the peneumatic trough gradually rose in the tube, and in time ran down into the flask. The latter being in an inclined position the water flowed gently down the neck and formed a distinct stratum above the strong solution of nitrate of copper. Some of the scraps of metal which had projected above the surface of the solution, were now immersed, partly in the latter and partly in water, and it was upon the lower portion of each of these scraps-the part immersed in solution of nitrate of copper-that crystallization had taken place.

The deposition of metallic copper under similar conditions. was observed by Bucholz, and other metals may, as is well known, be thus crystallized from solutions of their salts. The crystallization of the dinoxyd of copper was effected by Becquerel, but the arrangement of substances in his experiment was different from that now noticed-he placed a strip of copper in a saturated solution of the nitrate, the lower end of the strip touching some protoxyd of copper at the bottom of the solution. The crystals which he obtained were octahedral, not cubic.

ART. XXVII.-Review of Dr. Antisell's Work on Photogenic Oils, &c.

[Concluded from page 121.]

In describing the methods of purification proposed by Selligue, we shall make no attempt to follow their various details, our limited space compelling us to content ourselves with only the broadest generalities. Selligue sets forth at length two methods: 1st. A cold treatment which consists in agitating the oil with sulphuric, muriatic, or nitric acid. This agitation should be thorough, he says, and should be continued for a longer or shorter time according to the nature and quantity of the matter treated. Here follows a description of his agitators. After several hours' repose, the oil may be decanted, except from muriatic acid in which case more time and a larger amount of acid is required. After the oil has been thus separated from the deposit of tar, the acid remaining in it must be neutralized by means of an alkali. I prefer, says Selligue, to employ the lye of soap-boilers marking 36° to 38° [B.?], since it is easy of application, and produces a sure effect; I thus precipitate together the coloring matter and tar which would otherwise have remained in the oil. The oil is then decanted: if it is the first distillation of the crude oil I do not allow the mixture to subside entirely, preferring to leave a portion of the alkali mixed with the oil, and to distil off only 4ths of the latter. When the soda lye-in quantity slightly greater than is necessary to neutralize the acid-is added, the liquid must be agitated violently in order that each particle of the oil may be brought in contact with the alkali; this agitation must be continued until the color of the oil undergoes change.

*

*

*

The oil becomes less odorous and less highly colored after each such "cold treatment."

* *

After having been allowed to separate from the lye, the oil is decanted off; if it has not lost much of its color the process has been badly conducted. It should be stated that the oil must not be agitated several times with the alkali, for, by so doing, the dark color of the oil would be restored. As for the residues of the soda treatment, continues Selligue, they should be allowed to stand at rest during some days beneath a portion of oil, which will protect them from contact with the air; the clear lye at the bottom being then drawn off may be used for other operations, while the remainder is a soap, containing excess of alkali. By adding to it a little grease a soap can be made, or by adding water, grease may be separated. This grease is similar to that used for wagons.

2d. A warm treatment which follows the cold, and consists of a series of fractional distillations,-special operations for the purification of the "lightstuffs," being resorted to. For the details of these we must refer to the original specification of Selligue-a truly classical document which should be read by every one interested in the manufacture of coal-oils. Nor will our limited space permit us to cite the detailed "example" of his treatment which Selligue has described. We trust that we have already written enough to enable the reader to judge whether or no Selligue understood his business. As for paraffine, Selligue obtained it by subjecting the oil to a low temperature in order that this substance might crystallize. The mixed oil and paraffine was then thrown upon fine metallic filters through which the oil flowed while the paraffine was separated. Or one may separate, he says, the oil by imbibition, but this occasions a great loss of oil and also requires more labor. ** With this specification the scientific discussion of the subject by Selligue appears to have ceased, yet in the same year he repliest to a note published by Chenot who asserted that the oil of shale often contains arsenic, denying that arsenic can be found in the products from his own establishments. He again describes the locality and geological position of his shale, the method of distillation employed,-how the temperature is gradually elevated, &c.

This is of interest as showing that the manufacture of coal-oil in France was no ephemeral fancy, but for many years was a well established branch of industry. In this connection the scientific research, upon the commercial products of the distillation of bituminous shale, of Saint-Evre§ should also be mentioned. Contemporaneous with Selligue we find other inventors occupied with the same subject. Thus Holthorp,|| in 1841, claims that he has first discovered a means of purifying the fluid substance, which he calls "schiste," resulting from the distillation of coal or of bitumen. His attention was evidently chiefly devoted to the volatile naphthas, but he also obtained paraffine.

Guillard Meynier, in 1842, speaks of the fixed oil from shale, telling us that it may be used for lighting or lubricating and that paraffine may be separated when the oil is cooled or treated with alcohol.

In the same year Bonnet** in treating of liquids suitable for lighting incidentally mentions eupion and paraffine.

Nor should we omit to mention the very interesting article upon Hydrocarbures Liquides, by A. Mallet (in Laboulaye's Dictionnaire des Arts et Manufactures, 2d Ed., Paris, 1854ft), in which Selligue's processes are incidentally

A tolerably accurate English translation of this important patent may be found in the specification of M. A. B. B. Du Buisson, 1845; specification No. 10,726 of the English Patent Office.

+ Comptes Rendus, 1845, xx, 573. Comptes Rendus, 1849, xxix, 339. Brevets d'Invention, lxxviii, 91.

Ibid, xx, 306.

Brevets d'Invention, liii, 263. ** Ibid, lxxix, 63.

A portion of this article, which directly refers for the most part only to the volatile products suitable for "burning fluids," which may be obtained in any way from coal, is also contained in Dingler's Polytechnisches Journal, 1847, cvi, 128.

described. After discussing in detail the light volatile products obtained by distilling coal-tar, he says, we have still to speak of the carbo-hydrogers from shales; a branch of industry which we owe entirely to Selligue-cut off, alas! prematurely, in the midst of his career so full of discoveries and of useful works. As is well known, he obtained by distilling shales from the environs of Autun: I, volatile ethereal oils, II, fixed oils, III, oils combined with paraffine from which he prepared grease for carriages, IV, paraffine suitable for making candles, &c. Among all these bodies, Mallet continues, we have only to occupy ourselves with the volatile oils. Further on M. remarks that the acid and alkaline treatment used by Selligue is similar to that proposed by Barral for products from coal-tar. Thus far, says Mallet, these hydro-carbons have found no application,* partly on account of their insupportable odor when not purified and partly on account of their high price-about $10-00 the hundred lbs. when purified.

We have been at no pains to ascertain whether the industrial distillation of shales, so well grounded by Selligue, has been continued in France without interruption up to the present time, for we know of no reason to doubt the fact. Certain it is that coal-oils produced by French manufactories were exhibited, at the Exposition Universelle at Paris in 1855, and likewise in 1851 at London.† To any one familiar with the extreme slowness with which the practical applications of chemistry are even now imparted to, and recorded by, scientific writers, it would have been no matter of surprise if the results obtained by Selligue had remained uncopied upon the records of the French patent office. Such however was not the case. From the preceding citations it will be seen that his results were published in various well known journals and were widely diffused. Dumas, in his Traité de Chimie Appliquée aux Arts, expressly calls attention to them. They are also noticed in the Handwörterbuch der reinen und angewandten Chemie, von Liebig, Poggendorff u. Wahler, 1844, iii. 364. What we cannot explain is the apparent ignorance of these facts which was exhibited by several of the leading chemists of Great Britain on the occasion, of a trial, Young, v. White and others held in June, 1854, in the Court of Queen's Bench before Lord Chief Justice Campbell.

Several patents for the production of oils [coal-oils] from bituminous substances were meanwhile obtained in England. Butler, for example, in describing his "improvements in the manufacture of oil and gas" proposes to distil bituminous shales, &c. for the purpose of obtaining oil and gas free from naphthaline. The shale, best after wetting it with water if the principal object is to obtain oil, is distilled in common gas retorts under which a gentle fire is lighted. As soon as oil begins to flow over freely the fire is to be increased and the retorts brought to a red heat; a large quantity of gas is thus obtained which is collected in a gas holder. The rough oils, as Butler informs us, may be purified by washing with sulphuric acid, filtration, &c., or they may be used in the rough state for making oil-gas. The oils in their rough state are often found entirely free from oxygen, and if obtained by the process described never contain so much as is contained in the coal-tar obtained in the coal-gas works where the coal is thrown into retorts already brought to a red heat. These oils in their rough state are further distinguished from coaltar by their containing no naphthaline. Moreover the less volatile part of the

* It will be observed by the reader of Mallet's treatise that he is interested only in a single branch of the subject, viz., the volatile naphthas-" light stuffs," just as we are here giving prominence to another portion of it, viz., the fixed, or paraffineoil; and that he holds the naphthas from shale in small repute, since in his opinion they can never compete in the matter of cost with those from coal-tar. fA. U. MOREAN (No. 1361, Cat. 9), Bas-Rhin.

Paris, 1844, t. vii, p. 390; also iii, p. 315 of the Liege edition; and B. vii, S. 510 of the German translation.

Reported in Barlow's London Journ. of Gas Lighting, Aug. 10, 1854, vol. iii, p. 508. Patent granted Jan. 29, 1833. Specification No. 6375 of the English Patent Office.