Imágenes de páginas

phate of baryta, or he treats them by another residue which encunibers the soda-industry, viz., the oxysulphid of calcium, by which sulphid of manganese and chlorid of calcium result. The latter salt is now beginning to be used to prevent combustion and to water streets in summer, where by its hygroscopic properties it keeps down the dust.

All these researches were brought up in the first two sessions of the chemical section; but the third session was united with that of the physical section. On the next day there was an excursion to Baden Baden, when the Congress was fêted by that city. The Monday session was commenced at 11 o'clock, and there were many interesting experiments exhibited. The chief were

Dove's Experiment in Acoustics.—This experiment consists in rendering the tone from a vibrating diapason, very distinct, so that it could be heard through the whole hall, by causing it to vibrate in a certain relation to a glass flask containing water. The flask should not be filled and the diapason should not touch it, but be held by the hand in the prolonged neck of the balloon. The sound returned depends on the position of the two limbs of steel to the neck of the flask. The perception of sound is most distinct when the plane of the two branches is in the axis of the neck, and it is null when this plane is perpendicular to the axis.

Dove ascertained these facts while engaged in researches as to the question whether the ear, which is for a time sensible to a certain tone, becomes insensible to it again, as the eye does to a given color when it has for some time contemplated it. The eye may be said to habituate itself to certain colors, as the olfactory nerves do to persistent odors. Dove's researches returned an aflirmative reply to the point in question.

Magnus on the properties of iron in powder.-Metallic iron in a state of very fiue division has for some years been used in medical practice. It is thus obtained when the oxyd of iron is reduced by hydrogen. When well prepared this form of iron is so combustible as to take fire on exposure to air, burning with scintillation. A manufactory has lately been established in the Tyrol for making iron-powder, of very considerable fineness—although the process is mechanical, consisting in using very fine files. Its therapeutic properties have not yet been decided. It does not burn spontaneously in air although it is extremely combustible, as the following experiment by Magnus demonstrated to the section. When a burning body is approached to these Tyrolean filings they do not inflame unless they are previously suspended from the poles of a magnet. It is an experiment easily repeated and interesting in a lecture. If a magnet be thus armed with these fine filings, and a flame applied, a combustion begins which spreads rapidly, and if the magnet is jarred a shower of burning particles fall through the air.

BoettgerAction of cold and warm water on horny substances. This skillful experimenter whose tact in manipulation is well known, having obtained the floor of the Section, took a goose feather, placed it between the thumb and fore-finger of one hand and with the other crushed it into a crumpled mass. He then by a little manipulation restored it completely to its primitive state. The treatment by which this was accomplished was simple enough. After being left for some minutes in warm


water it was plunged into cold water; this restored the rigidity of the feather previously swollen by the warm water.

Schroeder-Relation between fermentation and crystallization.—In 1854 Mr. Schroeder in connexion with Mr. Dusch published a paper on fermentation and putrefaction, and showed that putrescent and fermentable substances could be indefinitely preserved, it instead of leaving such matter in common air, they were placed in vases filled with air that had been filtered through cotton. Flesh, soup, and all kinds of alimentary substances can thus be preserved, if the precaution has been taken previously to boil them in water.

Mr. Schroeder shows that what he has established concerning fermentation and putrefaction, is also true of crystallization. It is well known that a saturated solution of sulphate of soda remains liquid as long as it is in vacuo, but solidifies on access of air. Mr. Schroeder establishes the fact that crystallization does not take place if the air is made to pass through a tube filled with cotton.*

Mr. S. explained the results of his experiments in 1854 by supposing that the air filtered through cotton is deprived of the spores of cryptogamic infusoria, which are the cause of putresence and fermentation. If the experimnent on the sulphate of soda tends to establish a relation between fermentation and crystallization, it serves to prove also that these phenomena can take place without the presence at these cryptogamia or infusorial gerins, suspended in unfiltered air. This question which appeared to us finished by the earlier researches of Mr. Schroeder, comes up anew. These facts do not interfere with the mechanical theory of Liebig, nor that derived from the recent researches of Pasteur on the propagation of fermentation.

j. Nickles-- Electromagnets and Magnetic adhesion.—The experiments on this subject have been reported briefly in former communications. They have acquired a new interest since the French Government has ordered General Morin, of the Department of Arts and Trades, to take up that part of my researches which is applicable to locomotion on railroads.

Before my investigations, only two kinds of magnets were known, the straight and the horseshoe or bifurcate. In 1852 I made known the trifurcate magnet, (or magnet with three poles having only a single helix for magnetization although possessing considerable attracting power,) and the paracircular magnets, f and afterwards the circular. S . These last two kinds have some special properties, and are capable of transmitting motion as the revolution takes place, but the magnets which I call circular are polished at the circumference and without teeth. These magnets attracted much attention on account of their peculiarities and practical applications. One of them has been put in action on a large scale on the Lyons railroad.

This meeting of the German Association was without representatives from England, and but for the position of Carlsruhe would scarcely have had any from France. This is owing principally to the fact that Associations are in session in England, France, Italy and Germany at nearly the same

* Journal de Pharmacie and de Chemie, 1854, T. xxv, p. 314.
^ This Journ., xv, 104, 380. Ibid, xvi, 110. Ibid, xx, 99.

period of the year. The only way to remedy this difficulty is to substitute for these partial associations, a European Scientific Association, precursor to a Universal Scientific Association, which shall hold its sessions in turns at the different cities of the old and new continent.

Bibliography.-At H. Bossange’s : Researches on the Diffusion of Fluorine, by J. Nicklès. 60 pp. 8vo.


I. CHEMISTRY AND PHYSICS. 1. On the Siliciuret of Hydrogen.-Wöhler has communicated a purely chemical method of preparing the siliciuret of hydrogen discovered by Buff and himself as a product of the electrolysis of an alloy of silicon and aluminum. The method in question was accidentally discovered in Wöhler's laboratory by Martins, who found that a scoria or slag arising froin the preparation of magnesium by Deville's process, disengaged a spontaneously inflammable gas when treated with chlorhydric acid. The magnesium compound required in the preparation of the gas is prepared in the following manner: 40 grams of fused chlorid of magnesium, 35 grams of strongly dried fluosilicate of sodium, and 10 grams of fused chlorid of sodiun are to be finely pulverized and intimately mixed in a hot mortar. The mixture is to be introduced into a glass vessel which can be closed, and 20 grams of sodium in very small pieces added. The whole is to be mixed by agitation, and then forced at once into a Hessian crucible, heated to redness. The crucible is to be covered and heated, when the combination takes place with repeated decrepitations. When these have ceased and flames of sodium no longer appear, the crucible is removed from the fire, allowed to cool, and broken. It contains a greyishblack fused mass filled with globules and plates resembling cast iron. The coarser pulverized mass is to be introduced into a flask with two tubulures, through one of which passes a funnel with a tube long enough to pass to the bottom of the flask, to the other tubulure is attached a short and wide conducting tube. The entire apparatus is now to be filled with boiled water, and then plunged beneath the surface of the pneumatic cistern, so that every bubble of air is expelled. A collecting tube may now be filled with water and inverted over the orifice of the tube conveying the gas. Strong chlorhydric acid is now to be poured through the funnel. A violent reaction ensues and much foam unavoidably passes over into the collecting tube with the gas; a second tube may, however, be filled with the gas without foam. The properties of the gas are as follows. Each bubble inflames on contact with air with a white flame and a violent explosion. The silicic acid formed produces beautiful rings like phosphuretted hydrogen. The gas is completely decomposed by a feeble red heat, brown amorphous silicon being deposited. When burned against a plate of porcelain it gives a brown spot. With chlorine the gas explodes violently, but not with protoxyd or deutoxyd of nitrogen. As thus prepared the gas still contains free hydrogen, which makes it difficult to determine its constitution. Siliciuret of hydrogen precipitates various metals from their solutions. A salt of copper agitated with the gas yields a red pellicle of a siliciuret of copper, which in the air oxydizes to a lemon-yellow silicate of copper. Nitrate of silver yields with the gas a black substance which is doubtless a siliciuret of silver, mixed however with metallic silver: palladium is reduced by the gas to the metallic state. The greyish mass which yields the gas by the action of chlorhydric acid, appeared to consist of free silicon mixed with a siliciuret of magnesium which gives siliciuret of hydrogen by the action of chlorhydric acid, and of another siliciuret of magnesium which yields with chlorby. dric acid free hydrogen and protoxyd of silicon. In one case the authors succeeded in isolating a lead-grey aggregate of regular octaliedrops, sometimes presenting cubic surfaces. These were found to have the formula Mg2 Si, and as this compound yielded the spontaneously inflammable gas with chlorhydric acid, it is possible that the formula of this latter may be SiH2. Martins is engaged in studying the subject further.-Ann. de Chemie et de Physique, liv, 218, Oct. 1858.

[Note.—It must be remembered that Wöhler and Martins take the equivalent of silicon as 21, so that silica is SiO3. The siliciuret of magnésium above mentioned has no probable formula if we take silicon as 14, as appears necessary, since Marignac has shown the isomorphism of the fluosilicates and fluostannates. It is very much to be desired that those chemists whose means enable them to make such researches, should investigate the compounds of silicon with ethyl, methyl, &c. It can hardly be doubted that ethyl-zinc would give with chlorid or fluorid of silicon, a compound of ethyl and silicon having the formula Si(C4H3)2 since we should have a reaction expressible by the equation

2. Zn(C4115) + Si Cl2 = 2Zn Cl + Si(C4H16)2. A determination of the density of the vapor of ethyl-silicon would possess much theoretical interest. The results obtained by Hoffmann and Cahours in the formation of compounds of ethyl, &c., with phosphorus and arsenic render the existence of similar compounds of silicon and boron alınost certain.-W. G.

2. On protoxyd of iron with caustic potash as a reducing agent. Hempel finds that protoxyd of iron in the presence of an excess of caustic potash reduces iodic acid, bichlorid of platinum, and protochlorid of mercury. Platinum yields a black powder which after washing with water containing chlorhydric acid and drying, readily converts alcohol into acetic acid. A solution of chlorid of mercury treated with sulphate of iron and caustic soda, and then with sulphuric acid yields subcblorid of mercury and the filtrate is free from mercury. Nitrate and sulphate of protoxyd of mercury behave in this manner when a sufficient quantity of chlorid of sodium bas been previously added. The author recommends this process for the determination of mercury, the precipitated calomel being collected on a weighed filter, washed and dried. To determine inercury volumetrically, Hempel gives the following process, which yields very good results. The solution of the chlorid, niirate or sulphate of mercury (in the two last cases chlorid of sodiun must be added,) is to be introduced into a capacious flask with a ground stopple, an excess of protosulphate of iron and caustic alkali added, the flask well shaken and the oxyd of iron dissolved by adding dilute sulphuric acid. The subchlorid of mercury is allowed to settle and the supernatant liquid filtered off. After complete washing the filter may be pierced and the contents washed down into the flask with the rest of the precipitate. A large excess of dilute sulphuric acid and hypermanganate potash is then to be added, the flask closed and strongly shaken for two or three minutes. The undecomposed hypermanganate of potash is then to be removed by a solution of oxalic acid, and the excess of this last determined by means of a titred solution of the hypermanganate. The percentage of mercury is then easily calculated. — Ann. der Chemie und Pharm. cvii, 97.

3. On the Jodid of Methylen.—When powdered iodine is added to crystallized ethyloxyd-soda a strong reaction occurs, and the mass becomes fluid. By distilling the mass Buttlerow obtained a heavy oily substance dissolved in alcohol and precipitated from this by water: this is the iodid of methylen C2H212. The same substance is formed in larger quantity when one eq. of iodoform C2H13 is added to three eqs, of ethyloxyd-soda, and water added to the product of this reaction. The iodid is a heavy oily liquid of a yellowish color and of density 3.342: at 2° it solidifies to a crystalline mass. By heating the iodid with acetate of silver and a little crystallizable acetic acid to 100° extracting the mass with ether and then distilling, a colorless oily liquid passed over at about 170°. This is the acetate of methyl-glycol (CH:09)f 04. The author did not however succeed in obtaining methyl-glycol from this body.-- Ann. der Chemie und Pharmacie, crii, 110.

4. On the action of Ammonia upon Glyoxal.-By the action of nitric acid upon alcohol DEBUS obtained two new bodies termed respectively glyoxal C4H204 and glyoxylic acid C4H40s. By the action of a warm and concentrated solution of ammonia upon glyoxal, Debus obtained a base having the formula C12H6N4, its formation being represented by the equation

3(C4H204) + 4NH: = C12H6N4 +12HO. Glycosin the new base is a light white powder soft like talc and without taste or smell : it sublimes without melting, and yields beautiful needles. With bichlorid of platinum it yields a beautiful yellow crystalline powder, which has the formula C12H6N4 + 2(HCI, PtCl2) or C12H3N4Cl2, 2 PtCl2. The rational formula of glycosin according to Debus is

( C4H2) NA C4H24.

7 C H2 The mother-liquor from which the glycosin is obtained yields with oxalic acid the oxalate of a new base which the author terms glyoxalin, and which has the formula C6H4N2. Glyoxalin is colorless and crystalline; its platinum salt has the formula C6H4N2, HCl + PtCl2 and crystallizes in magnificent orange-red prisms. The formation of glyoxalin is expressed by the equation

2(C4H204) + 2NH3 = C6H2N2 + C2H204 + 4HO. Ann. der Chemie und Pharmacie, cvii, 199.

5. On the constitution of Tantalite.-H. Rose has published an elaborate discussion of the analyses of tantalite from different localities, and arrives at the conclusion that the formula of the unaltered mineral is FeO, 2TaO2, a portion of the tantalic acid being replaced by stannic acid SnO2 and zirconia, which latter has probably the formula ZrO2, as Deville and Troost have suggested.-Pogg. Ann., civ, 85.

« AnteriorContinuar »