of light has been observed; at first this was supposed to be the case with all gases; but M. Soissy, of Lyons, stated, that it happened only with oxygen, air, and chlorine, a result which has been confirmed by M. Thenard. The latter philosopher, on reflecting that the pistons used had been greased, thought the light might perhaps be due to the formation of a little water, or muriatic acid, in these cases; and therefore repeated the experiments with pistons moistened only with water, and then found that no light was evolved. He then made other experiments on the inflammation of various substances in compressed oxygen, chlorine, &c. We are constrained to omit the detail of these, but the following are the conclusions to the paper-1. No gas becomes luminous of itself by pressure exerted in the ordinary manner in cylinders by pistons. 2. The highest pressure which can be given by the hand to gas in a tube of glass raises the temperature much above 400° F. Powders which are not decomposed at this temperature explode instantly in azote, hydrogen or carbonic acid gas, suddenly compressed. 3. Paper and wood inflame in oxygen suddenly compressed, and oiled paper inflames in the same manner in chlorine. 4. If the gases be compressed more forcibly and suddenly, they would doubtless attain a much higher temperature; but it is not probable that they would of themselves become luminous, except at very high temperatures*. 8. ON OXAMIDE, A SUBSTANCE WHICH APPROXIMATES TO This substance is produced whenever oxalate of ammonia is distilled, and the name oxamide, or oxalamide, is given to it provisionally, as indicating that it is formed of oxalic acid and ammonia, and by particular treatment can reproduce these bodies. When acted upon by potash, it yields 36 per cent. of ammonia, though it contains none; by the same treatment it can produce 82 per cent. of oxalic acid, and yet includes none of that body. These curious properties associate oxamide with the phenomena which occur when animal substances are made to yield ammonia by the action of alkalies, and also with those new observations due to MM. Vauquelin and Gay Lussac, on the developement of oxalic acid, when organic matters are acted upon by potassa. When oxalate of ammonia is distilled, it first loses water; the crystals become opaque; then, where close to the heat, fuse, boil, are decomposed, and disappear without any change occurring in the more distant parts of the mass. Ultimately, a little carbon remains, but nearly the whole has been volatilized. The water which has passed over into the receiver contains a flocculent substance; a thick deposit of a dull white matter also lines the neck of the retort; both these are oxamide. To isolate it, the whole is diffused in water, filtered, and washed, the peculiar substance remains in the filter. 100 parts of the oxalate of ammonia yield 4 or 5 of oxamide; the * Ann. de Chimie, xliv., 181. other products are ammonia, water, carbonate of ammonia, carbonic acid, oxide of carbon, and cyanogen. Oxamide occurs in imperfectly crystallized plates, or as a granulated powder. When well washed and pulverized, it is a dirty white powder, looking like uric acid, having no taste or odour, and not affecting test papers. Heated carefully in an open tube, it volatilizes; heated in a retort, part sublimes, whilst part is decomposed, yielding cyanogen and a very bulky, light charcoal remains. It is scarcely soluble at common temperatures; a saturated solution at 212° F. deposits confused crystalline flocculi of the unaltered sub stance. As oxamide is an azoted substance, the ratio of the azote and carbon to each other was first ascertained by combustion with oxide of copper in a glass tube. In this mode of analysis, M. Dumas points out the necessity of collecting the whole of the gas evolved, and ascertaining its composition. Portions of the gas often differ from each other; and if the composition of the whole be deduced from these portions, great errors may occur. In experiments on the oxamide, two volumes of carbonic acid were produced for each one of azote, so that the carbon and the azote are in the same proportion as in cyanogen; 100 parts of oxamide gave 26.95 carbon, and 31.67 azote. When oxamide was heated with great excess of concentrated sulphuric acid, it yielded a mixture of carbonic acid and of carbonic oxide gases in exactly equal volumes; no cyanogen was formed; this is precisely what takes place with oxalic acid. When the sulphuric acid was diluted and saturated with potash, much ammonia was evolved, so that a sulphate of ammonia had been formed. In this way, therefore, oxamide is resolved into ammonia, carbonic oxide, and carbonic acid. When oxamide was heated for some time with strong solution of potassa in great excess, much ammonia was disengaged. The potash, afterwards neutralized by nitric acid, was found to contain oxalate of potassa, so that potassa evolves oxalic acid and ammonia from oxamide, and those substances only. These results created a suspicion, that oxamide was to oxalate of ammonia what pyrophosphoric acid is to the ordinary phosphoric acid. The substance, therefore, was compared to oxalate of ammonia, supposed to be dry, both by theory and experiment. The carbon is to the azote as 2 proportionals to 1 in both compounds; but 100 parts of oxamide contain 26.95 of carbon, and 31.67 of azote, whilst 100 parts of dry oxalate of ammonia contain only 22.6 of carbon, and 26.6 of azote. When 100 parts of oxamide were converted by potash and sulphuric acid into the elements of oxalate of ammonia, they gave products amounting to 120 parts, i. e., 26.95 carbon, 31.67 azote, 54.70 oxygen, and 6.3 hydrogen=119.62. Now, the sulphuric acid and the potash could neither of them give carbon or nitrogen, but might communicate oxygen and hydrogen from the water present with them: withdrawing 19.62 of these elements in the proportion to form water, there remains the following composition as nearly as may be : Oxamide may, therefore, be considered at pleasure as a compound of cyanogen and water; or as a compound of deutoxide of azote, and bicarburetted hydrogen; or as a compound of oxide of carbon and a hydruret of azote, different to ammonia. Whichever way it be viewed, if 2 volumes of vapour of water are added to it, dry oxalate of ammonia is produced; and it is in this way, apparently, that sulphuric acid and potassa act. In conclusion M. Dulong remarks, that many animal matters, as albumen, gelatine, fibrine, &c., act with potassa as oxamide does. Uric acid approximates to it: hippuric acid also resembles it. All these bodies have properties in common with it so characteristic, that M. Dulong has been induced to commence an experimental comparison of them with this new substance*. 9. PREPARATION OF NITROGEN.-(Professor Emmett.) When zinc is dipped into fused nitrate of ammonia, it is instantly oxidized and dissolved, and nitrogen and ammoniacal gases are evolved. The zinc disappears with as much rapidity as when exposed to the strongest mineral acids; and, at the same time, so completely sustains the requisite temperature, that it becomes unnecessary to continue the application of heat after the action commences. heat required is 280° or 300°, but a small piece of zinc soon elevates it to 540°. No nitrous or nitric oxide could be detected in the evolved gas, and therefore Professor Emmett recommends the operation as one well fitted to supply nitrogen gas. The A tubulated retort is to be partly filled with the nitrate of ammonia, and a cork fitted to the tubulature. Through this cork is to pass freely either a knitting-needle or an iron wire, holding, by means of a hook, the coil of zinc. As soon as the salt has entered into fusion, the knitting-needle must be pushed down far enough to place the zinc in contact with the nitrate. This arrangement is not only convenient but necessary; for if the zinc be thrown at once into the fused salt, the action will prove too violent and unmanage able; whereas, when contact is not constantly maintained, there is a strong tendency towards a vacuum in the retort, which would endanger its safety. By the process here recommended, there is no liability to accident, and the quantity of nitrogen may be easily * Ann. de Chimie, xliv, 113. regulated, by raising or lowering the zinc. Every grain of the metal furnishes nearly a cubic inch of the gas, while the ammonia, which also escapes, becomes wholly condensed as soon as it enters into the water of the pneumatic cistern *. 10. ACTION OF MIXED NITRATE AND MURIATE OF AMMONIA ON GLASS. When equal parts of these salts are mixed and fused between two watch-glasses, the under glass becomes corroded nearly to one-half of its thickness, and the effect even extends to the cover. The heat of a spirit-lamp is quite sufficient for this purpose. Here, without water, or even perfect fusion, the alkali is entirely removed, and the silex left, forming a snow-white opaque substance, so soft as to admit of being cut through with the point of a needle or knife: green glass is not so easily affected, owing to its greater hardness and the absence of lead. The fused nitrate alone, if confined between watchglasses, also produces slight corrosion, but the effect is so remarkable when the nitro-muriate is employed, that a person operating upon an unknown mineral, and ignorant of this property, would be induced to attribute the result to the presence of fluoric acid. Indeed, when we consider that the effect appears to depend upon the liberation of nitro-muriatic acid, or perhaps even to highly concentrated nitric acid alone, it does not seem improbable that similar cases have often occurred by the common mode of analysing; and this opinion is further strengthened by the fact, that some minerals, as the chondrodite, appear to have furnished fluoric acid to one operator and not to another t. 11. PULVERIZATION OF PHOSPHORUS.-(Casaseca.) If phosphorus be put with alcohol into a bottle, and shaken for some time, it may be obtained in powder of the utmost tenuity, which, when diffused through the alcohol, appears as if it consisted of a multitude of minute crystals. 12. INFLAMMATION OF PHOSPHORUS BY CHARCoal. Dr. Bache, of Philadelphia, states, that, at the temperature of 60° F., or upwards, carbon in the form of animal charcoal, or lampblack, causes the inflammation of a stick of phosphorus powdered with it; the effect takes place either in the open air, or in a close receiver of a moderate size ‡. 13. PREPARATION OF BI-CARBONATE OF SODA. The following method of preparing this salt, in the large way, is described by Mr. F. R. Smith, of Philadelphia. The ordinary crys *Silliman's Journal, xviii. p. 259. +Ibid. xviii. p. 258. Silliman's Journal, xviii. p. 373, tals of carbonate of soda are placed in a box made on purpose, and are surrounded by carbonic acid gas under pressure. The salt absorbs the gas, and, as the bi-carbonate requires but little water, much of that contained in the crystals of the original carbonate drip away in the form of a solution. When gas ceases to be absorbed, the salt is taken out, and dried at a moderate temperature. Upon examination, after the absorption of gas has ceased, the portions of salt are found in their original form, but porous and friable, and the fracture without lustre. Each consists of an aggregation of crystalline grains as white as snow, and scarcely alkaline to the taste. In this way all the trouble of solution, evaporation, &c. involved by the ordinary process, is obviated. The production of gas should be continued for a sufficient time, and the subsequent drying of the salt should be at a moderate temperature, or else portions of carbonate may remain. When a portion of salt thus prepared was washed with a little water, to remove any carbonate, then dried and analysed, it proved to be, not sesqui-carbonate, but true bi-carbonate. M. Boullay has repeated the process on a large scale, and obtained exactly similar results*. 14. ROCK SALT IN ARMENIA. Armenia was incorporated with Russia in 1828, by the treaty of Tourkmantchaï, made with Persia. The salt is found in a mountain two leagues and a half from Nakchitchevane, situated on an extensive plain extending along the left bank of the Araxes. The mountain is seven leagues and a half in circumference, and, from the appearance of very ancient works, has evidently yielded salt for many ages. These remains consist of enormous horizontal galleries, supported by pillars of salt; and, according to the traditions of the people, many mines have been abandoned from the difficulties of working them, occasioned by the depth of the strata and frequent inundations. The Persian government, for the last fifteen years of its time, let them for a sum equal to 16,000 francs annually. The salt is worked by gunpowder; the works are wrought by the inhabitants of a small neighbouring village, consisting of Armenians and Tartars, from three to twenty persons being required at a time. The Russian government has let the works, since March, 1829, for a year, for a sum equal to 16,000 francs t. 15. PREPARATION OF LITHIA.-(Quesneville, fils.) One part of triphane is pulverised in water, mixed intimately with two parts of pulverised litharge, put into a crucible and heated to whiteness. In a quarter of an hour the whole is liquid; it is to be Journ. de Pharm. 1830, p. 118. |