Page images
PDF
EPUB

phorus has been kept, iodine is liberated. The reaction is due to the phosphorous acid present. To detect an iodide, this is first oxidized by boiling with a few drops of sodium hypochlorite. The addition of the phosphorus water sets free iodine at once, which is recognized by starch or carbon disulphide.

Berthelot has studied the thermic conditions attending the formation of ozone. He finds that in the production of one molecule of ozone from oxygen there is an absorption of 29.6 calories. Being therefore a body formed with the absorption of heat, its activity chemically is accounted for: it is a magazine of energy stored up under the influence of electricity.

Cohne has observed that if a sprig of any fresh plant be placed in a weak solution of hydrogen peroxide, oxygen is disengaged which is strongly ozonized. If flowers are upon the sprig, they also evolve oxygen, but less actively. A convenient method of setting free a little ozone in the air of an apartment is to place a bouquet of flowers in weak hydrogen peroxide in place of ordinary water.

Kämmerer has called attention to the occurrence of gelatin in all forms of water coming from the soil, and has suggested that water intended for consumption should always be tested by means of tannin for this substance. If no precipitate or turbidity appears after standing twenty-four hours, the absence of an appreciable quantity of gelatin is assured. Any turbidity, however, proves the water impure.

Frankland has published a paper on water - analysis, in which he examines the value of the albuminoid-ammonia process, and concludes that it is “entirely useless in the examination of waters for sanitary purposes.” He claims, however, for the combustion process, that it is the only one which gives trustworthy information concerning the organic matter present, the only one which can determine the carbon, and the only one which shows the ratio of nitrogen and carbon.

Fairley has studied the action of various bodies on hydrogen dioxide, with a view to determine the cause of the decomposing action they exert. In the case of the metals silver, for example-he believes that there is first an oxidation, and then a reduction again, due to the reaction of the silver oxide upon the hydrogen dioxide.

Cooke has described a method for manipulating hydrogen sulphide which possesses many advantages. In general, the apparatus used is that commonly employed for generating and dispensing carbonic-acid water, some minor modifications being made in it.

Berthelot has examined experimentally the assertion of Schönbein that, in presence of alkalies, the nitrogen of the air is oxidized to nitrous compounds by ozone. Both oxidation of phosphorus and the silent electric spark were used to produce the ozone. But while he confirmed Schönbein's statement that nitrous compounds are formed in presence of oxidizing phosphorus, the author could not obtain evidence of the oxidation of the nitrogen by the ozone.

Berthelot has also called attention to the absorption of free nitrogen at the ordinary temperature by various organic bodies, notably benzene, oil of turpentine, marsh gas, acetylene, and even cellulose, under the influence of the silent electric discharge.

Storer has examined elaborately Schönbein's test for nitrates, which consists in applying the iodo-starch test after reducing to nitrites by means of zinc. In his opinion, the fatal defect of the test is the production, even by the action of zinc on pure water, of hydrogen peroxide, which colors the iodo-starch. He finds that this may be entirely obviated by acidulating the water before reducing. One tenth of a milligram of nitric acid in 50 cubic centimeters of water containing two drops of dilute sulphuric acid gave the reaction distinctly.

A new and apparently satisfactory process has been proposed by Etard for the preparation of alkali nitrites as reagents, which consists in reducing the corresponding nitrate by a sulphite. Equivalent quantities, for example, of potassium nitrate and potassium sulphite, previously well dried, are mixed together and fused in a crucible. After cooling, the mass is taken from the crucible, pulverized, and treated with alcohol, in which the nitrite only is soluble. Or the separation may be effected by crystallization.

Hampe has made a somewhat exhaustive investigation of the so-called boron obtained by different methods, and concludes that no pure boron in crystals has ever yet been seen. He finds that the black monoclinic prisms produced when

carbon is absent consist of about 17.30 per cent. of aluminum and 82.70 of boron, corresponding to the formula AIB,2The yellow crystals, quadratic in form, which have been supposed to be an allotropic form of boron, the author finds to contain 13.15 per cent. of aluminum, 3.76 of carbon, and 82.81 of boron, from which he derives the formula C2A1,B48 for the substance.

Wright has continued his studies upon the gases contained in meteorites, and now gives the results of his examination of the Kold Bokkeveld meteorite, which, though stony, contains considerable carbon and some bituminous matters. It yielded 25.23 volumes of gas, of which 93.11 per cent. was carbon dioxide, the remainder being carbon monoxide, marsh gas, hydrogen, and nitrogen, the two latter in minute quantity. It also yielded ten per cent. of water, in which chlorine and sulphurous oxide were detected. The manner of occurl'ence of the

gases within the meteorite is also discussed. A note has appeared by Böttinger giving the results of his experiments with carbonous oxide and hydrogen cyanide, in a research upon glyoxylic acid. He finds that when pure carbonous oxide is conducted over pure dry hydrogen cyanide, well cooled, it is actively absorbed. If the solution be mixed with a concentrated solution of hydrogen chloride and agitated, no evolution of gas takes place, even on agitation, the liquid separating, on standing, into two layers. If, however, the vessel be removed from the freezing mixture, a rapid streain of pure carbonous oxide is evolved. Pure hydrogen cyanide is left, showing that the CO was simply dissolved. He hence calls attention to the remarkable solubility of carbonous oxide in hydrocyanic acid.

Hartley has made further examinations of the liquids contained in mineral cavities. He finds that the liquid carbon dioxide present varies considerably-from 27.27° to 33.7° C. -in its critical point in different mineral specimens, often varying in different cavities in the same mineral specimen. The presence of this substance in sapphire and topaz leads him to the supposition that these minerals may have been formed by the action of aluminum fluoride or chloride upon calcium carbonate at high pressures, producing alumina and carbon dioxide. Where water is also present in the cavity it would seem that the reaction had taken place in presence of moisture. As to the diamond, the author thinks that this mineral is the result of the action of reducing agents upon very highly compressed carbon dioxide at temperatures above its critical point-a condition of things which suggests a new direction for speculation and experiment.

Zöller has recommended the vapor of carbon disulphide as an antiseptic agent. Prepared from potassium xanthate, its odor is but trifling. Experiments show that five grams of this liquid volatilized in a space of about one seventh of a cubic meter will preserve twenty kilograms of meat placed in this space for from two to three weeks.

METALLIC. Jean has proposed a method of titrition for the sulphates of the alkalies, which is as follows: The aqueous solution of the sulphate is treated first with baryta water in excess, then with carbonic-acid water decanted from the mixed precipitate of barium sulphate and carbonate, the liquid boiled, the whole filtered, the precipitate washed out, the filtrate and washings concentrated and titered as usual with a standard sulphuric acid. From the quantity of free alkali carbonate present, the quantity of sulphate originally united to it is known, being the exact quantity employed in neutralizing the alkaline filtrate.

Johnson has prepared potassium tri-iodide, by evaporating over sulphuric acid a saturated solution of iodine in potassium iodide. At first dark-colored cubical crystals of the iodide, colored by iodine, were deposited; but in a few days lustrous dark-blue prismatic crystals, sometimes two inches long, separated, which had the composition of the tri-iodide, and were extremely deliquescent. Their specific gravity was 3.498.

Frey has given the details of the manufacture of the alkali-earth metals in Görlitz which were exhibited in London and Philadelphia. In general the electrolytic method of Bunsen is closely followed, the current being weaker. From two and a half to four grams were produced at each operation. Calcium is not yellow, but resembles aluminum closely, being brittle like it, and not being malleable or tenacious. Strontium is bright brass-yellow, very malleable, easily rolled and drawn, and oxidizes much easier than cal

cium. Barium cannot be obtained as a globule, its fusing. point apparently being above that of cast iron. From amalgams of this metal, by distilling off the mercury, masses of over 100 grams were obtained, sintered together. Lithium was obtained in two-gram globules. Cerium has the precise properties given by Wöhler, burning with explosive violence.

Mallet has described an aluminum nitride obtained by acting upon sodium carbonate by metallic aluminum at high temperatures. The remaining metallic regulus showed projecting crystalline points, which were separated by solution in hydrochloric acid and examined. They were apparently short rhombic prisms, with dihedral summits of a bright honey yellow color and translucent. They were brittle and not hard enough to scratch glass. On exposure to the air for a week or two, ammonia is evolved and alumina is left. Fused with caustic alkali, ammonia is given off and an alkali aluminate formed. Analysis showed 67.9 to 68.27 per cent. of aluminum and 31.73 to 32.1 per cent. of nitrogen, corresponding very well with the formula Al,N2, which requires 66. 18 per cent. of aluminum and 33.82 per cent. of nitrogen.

Gladstone and Tribe have continued their researches on the simultaneous action of iodine and of aluminum upon ether and compound ethers. With ether the experiment was made by taking twenty cubic centimeters and adding to it twenty-seven grams of iodine and two grams of finely cut aluminum foil. The temperature rose at once, and the ether began soon to boil violently, being prevented from escaping only by an inverted condenser. Ethyl iodide and aluminum iodo-ethylate were the only products. The compound ethers used were the acetates of ethyl and amyl, and the results of the reaction were aluminum acetate and iodide of the alcohol radical. The authors use these reactions to explain the action of aluminum and iodine upon water.

Heumann has succeeded in producing an ultramarine containing silver in place of sodium by heating the blue ultramarine with a concentrated solution of silver nitrate in sealed tubes to 120° Fahr. for several hours. The product, washed with boiling water, and separated by agitation from the metallic silver, appeared under a magnifier as a perfectly uni

« EelmineJätka »