the air. This subject has, however, been fully investigated by Wolffhugel, who finds that, while a given quantity of fresh air yields a very visible ozone reaction, yet ten or twelve times that quantity taken from the interior of dwellings produces no effect, even when the rooms are unused, having previously been well aired. Wolffhugel has also shown that there is a great absence of ozone in the air near the ground.-7 C, 11, 122.

DECOMPOSITION OF WATER.

Gladstone and Tribe find that when aluminum foil and iodine are placed together in water, hydrogen is copiously evolved. The same phenomenon takes place if aluminic iodide be substituted for iodine, its formation really being the first part of the reaction just described. Aluminic bromide or chloride acts in much the same manner, the aluminum used being almost completely oxidized. The same experimenters sought to determine whether zinc or iron, heated with solutions of their respective iodides, would yield hydrogen, and obtained only negative results. These metals, however, with aluminic iodide in water, produced readily a copious evolution of the gas. Aluminum alone decomposes water, according to Deville, only at a white heat. Gladstone and Tribe, by simply coating aluminum foil either with copper or platinum, procured couples which effected the decomposition quite easily at the low temperature of 100° Centigrade.-21 A, 822, September, 1875.

DECOMPOSITION OF WATER BY PLATINUM.

But

Deville and Debray find that when a mixture of potassium cyanide and spongy platinum is heated together in the neighborhood of a little water, at about 500° or 600°, a vacuum having first been established, great quantities of hydrogen are evolved, and the well-known platino-cyanide of potassium is formed. The hydrogen is not pure, but contains small quantities of ammonia, and from four and a half to twelve per cent. of carbonic oxide.-6 B, January 24.

CRYOHYDRATES.

About a year ago Professor Guthrie described under the above name a set of hydrates which exist only at very low

temperatures. Whenever a crystalline salt is dissolved in water and the solution frozen, solidification takes place below the Centigrade zero, and a definite compound of the water with the salt is formed. And whenever any crystalline salt is mixed with ice or snow, the same compound is formed, and a fall of temperature ensues. Hence with every crystalline salt a freezing mixture may be prepared. Guthrie now extends his observations to colloid bodies, and shows that they act very differently from the crystalloids. Thus from a solution of gum, gelatin, or albumen all the water separates as ice at 0° Centigrade, and no cryohydrate is produced. This new distinction between crystalloids and colloids seems to be of the very highest importance.-1 A, June 30.

NATURAL DEVELOPMENT OF SULPHURETTED HYDROGEN.

Faulquier narrates a curious phenomenon which took place during the summer of 1875 at Palavas, near Montpellier. In the vicinity of this place are extensive salt marshes, which, in consequence of persistent north winds, have become almost dried up. The accompanying heat of the season has produced a rapid decomposition of the organic matter in the soil, which has been accompanied by a development of sulphuretted hydrogen. The existence of this gas has been very palpable to the senses, and has also produced an unexpected influence upon the residences near by, the painted surfaces of the houses having first turned brown, and finally almost entirely black, while the paint even in the interior of the houses has become much altered. All silver and silvered objects have also become blackened by the same influences. Another effect is that of loosening and crumbling away of the plaster between the joints of the building-stones, which Faulquier attributes not to the sulphuretted hydrogen, but to the saline particles contained in the atmosphere.-1 B, September 5, 346.

AMMONIA IN SULPHURIC ACID.

Professor F. H. Storer finds that ammonia in traces is an invariable contaminant of sulphuric acid. Nine samples of acid were examined from different manufactories, seven being obtained direct from the makers. These were kept previous to examination in tightly stoppered bottles, and in every case

the portion tested was taken from the middle of the bottle containing it. The same impurity, ammonia, was also found in a very large number of other chemicals in the preparation of which sulphuric acid is employed. Professor Storer thinks that the ammonia may get into the acid, partly from the air, partly from the water employed, partly from a reduction of the nitric acid used in oxidizing the sulphur dioxide formed in the first stage of the sulphuric manufacture. In fact, he finds by direct experiment that whenever dilute nitric acid is made to act either upon lead or sulphur (as in the leaden chambers of sulphuric-acid works) traces of ammonia are produced.-4 D, December, 1875.

AMMONIUM NITRITE.

This extraordinary substance has been reinvestigated by Berthelot, who obtained it by double decomposition from barium nitrite and ammonium sulphate. The filtered solution, evaporated over quicklime in vacuo, yields crystals of the substance desired. It is also formed by the simultaneous reaction upon each other of nitrogen tetroxide, dry ammonia, and oxygen. It forms a white, crystalline, deliquescent salt, having peculiar elastic properties. It decomposes slowly at ordinary temperatures; at 60° to 70° Centigrade it explodes violently; under a severe blow it detonates. In solution the salt, anomalously, decomposes more rapidly than when dry; heated, torrents of nitrogen are evolved. It seems to be one of the least stable bodies known.-Annales de Chimie et de Physique.

ACTION OF NITRIC ACID ON METALS.

The subject indicated by the heading of this paragraph has recently been studied by Mr. J. J. Acworth, who explains some points which have often led to confusing uncertainties. Thus nitric acid, acting in the cold on copper, should yield nearly pure nitric oxide, but does not always. Acworth finds that as cupric nitrate accumulates in the solution, nitrous oxide begins to be formed; and that when the above-named salt becomes sufficiently abundant the latter gas is given off almost alone. If ammonic nitrate be added to the nitric acid during its action on copper, the gases evolved consist chiefly of nitrogen with nitrous oxide, and

smaller quantities of nitric oxide. The acid, acting upon zinc or mercury in the presence of ammonic nitrate, yields little gas but nitrogen; with silver, nitric, but no nitrous oxide is also formed.-21 A, September, 1875.

CONSTITUTION OF PHOSPHORUS OXYCHLORIDE.

The constitution of phosphorus oxychloride has long been a matter of discussion. Ira Remsen now shows that the compound may be formed by the direct action of ozone upon the trichloride. This fact strengthens the view which regards phosphorus as pentatomic, and obliges us to look upon the atom of oxygen in the oxychloride as directly satisfying the two bonds of affinity left free in the trichloride.-4 D, July.

DISCOVERY OF VANADIC ACID IN MAGNETIC IRON.

Dr. Isidor Walz communicated to the American Chemical Society, May 4th, that he had discovered 0.3 to 0.4 per cent. of vanadic acid in magnetic iron ores from the Church Mine, New Jersey. Apart from the scientific interest attaching to the rich occurrence of that rare metal on our soil, this discovery may lead to important practical results, as the salts of vanadium have recently begun to play an important role in the preparation of aniline black, indelible marking-ink, etc., and the supply has hitherto come from much poorer sources than the one now disclosed.

CARBON FROM THE ROOF OF A GAS-RETORT.

Mr. A. McDougall exhibited before the Manchester Literary and Philosophical Society a specimen of carbon ob tained from the roof of a gas-retort, resembling graphite in its almost metallic lustre. It was undoubtedly produced by the decomposition of the hydrocarbon gases in the intense heat of the retort; and it is suggested that its formation may throw some light on that of graphite, as that substance is always associated with rocks that have been subjected to igneous action.-18 A, April 9, 1875, 89.

LIQUID CARBON DIOXIDE IN MINERAL CAVITIES.

W. Noel Hartley, examining the liquid which occasionally occurs in the cavities of quartz, has corroborated the conclusions of Davy and Brewster with regard to its being lique

fied carbon dioxide. He noted that at the temperature of about 31° Centigrade the liquid in such a cavity disappeared entirely, to return upon cooling. Dr. Andrews gives 30.92° Centigrade as the critical temperature of carbon dioxide, so that there can no longer be any doubt concerning the nature of the liquid under examination.-1 A, March 26.

CARBON MONOSULPHIDE.

Sidot finds that when carbon disulphide, inclosed in hermetically sealed tubes, is exposed for about two months to the action of sunlight, brown flakes of the new monosulphide, CS, are deposited. This substance, dried and purified, is a chestnut-brown, tasteless, odorless powder of 1.66 specific gravity. It is insoluble in water, alcohol, turpentine, or benzol; boiling ether or carbon disulphide dissolves traces of it. Hot nitric acid dissolves the monosulphide to a red liquid; but chlorohydric acid is without action upon it. A boiling solution of caustic potash takes it up freely, forming a blackish brown liquid, from which acids reprecipitate the substance. At 200° Centigrade the new sulphide decomposes, sulphur distilling off, and carbon remaining behind.—18 C, 1875, September 29.

A NEW CLASS OF CYANIDES.

Gaston Bong, studying potassium ferrocyanide and some of its derivatives, has obtained a remarkable new double salt. It is formed by treating a mixture of the common yellow prussiate and potassium chlorate with sulphuric acid until a persistent blue color is produced. The resulting mass is heated gently, extracted with water, neutralized with sodium carbonate, boiled and filtered. This solution, by careful crystallization in vacuo, yields black crystals, which, readily soluble in water, give it an intense violet color. The compound may be regarded as the type of an entirely new class of double cyanides, and its relation to well-known ferroand ferricyanides may be indicated by formula:

Thus, in this series, every added potassium atom needs a doubling of all the other atoms in the molecule. The new