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equation, which may be called Esson's equation, on being applied to the numerous exact observations recorded by Gladstone, leads Dr. Mills to the conclusion that 54 per cent. of the discordances between the theory and the observations are such as would on the average be found in any very good analytical work, 33 per cent. occur in ordinary good analytical works, and the remaining 13 per cent. lie on the average within the limits allowable in such estimation of colors as Dr. Gladstone made. The ordinary equations of chemistry represent the result of distributing atomic weight, and give no account of the work done. Esson's equation and conclusions worked out by Gladstone, on the contrary, represent a dynamic process as well as the distribution of weight.-7 4, XLVIII., 246.
WATER OF CRYSTALLIZATION.
Professor Guthrie states that the absorption of heat, which occurs when the salt is dissolved in a liquid, depends not only on the relative specific heat of the salt in the liquid, but also on the molecular ratio of the resulting solution. This ratio declares itself, first, optically by the refractive index; second, by the density; third, by the heat absorbed when a saturated solution is mixed with the medium; and, fourth, by the heat absorbed when the salt itself was dissolved in a certain quantity of the medium. The conclusion which he draws from his observations is that every salt soluble in water is capable of uniting with water in a definite ratio, forming definite solid compounds of distinct crystalline forms and constantly melting and solidifying temperatures.-12 A, XI., 59.
VIDAL'S APPARATUS (EBULLISCOPE) FOR THE DETERMINATION
The following instrument, an improvement on that originally devised by Vidal, it is claimed will indicate accurately the percentage of alcohol in liquids in less than ten minutes, using but little of the liquid. It depends upon the fact that sugar, resin, citric and tartaric acids do not change the boiling point of alcohol in which they may be dissolved, and consequently the determination of the boiling point will show the amount of alcohol present in an aqueous liquid. It consists of a conical boiler, closed at the top with a screw-cap
having two apertures in it, through one of which a thermometer, bent at right angles, is inserted, in such a way that the bulb can be immersed in the liquid or the vapor at pleasure, while upon the other is screwed a condenser, consisting of two concentric cylinders. At diametrically opposite points at the bottom of the boiler the ends of a small curved spiralshaped tube are inserted. This tube, filled with the same liquid as the boiler, passes directly through the chimney of a lamp, and consequently receives upon a small surface the whole of the heat of the lamp. The fluid, thus gradually warmed, circulates through the tube and the boiler, until the whole of it has reached the boiling point, when the thermometer becomes stationary, and will remain so for ten minutes. A horizontal movable scale is fixed to the top of the boiler, by comparing which with the thermometer the amount of alcohol is indicated in degrees from 0 up to 25.-14 C, CCXIII., 87.
SPECIFIC HEAT OF CARBON, BORON, AND SILICON.
In 1819 Dulong and Petit discovered that when the specific heat of a solid element was multiplied by its atomic weight, the product was a constant quantity in the neighborhood of 6. Later, however, it was found that carbon, boron, and silicon were apparent exceptions to this rule. These elements have been studied in this direction by many experimenters with very discordant results; as, for instance, some found that the different modifications of carbon had the same specific heat, others that they varied widely. The subject has lately been thoroughly worked up by Dr. H. Friedrich Weber, whose results at last seem to be conclusive. Carbon he examined as diamond, graphite, coal, and charcoal, and boron and silicon in their crystalline varieties. His experiments were conducted at temperatures varying from -80° to +1000° Centigrade, and with the finest modern apparatus. With all three of the elements above named the specific heat increases very rapidly with the temperature. At 600° for carbon and boron, and at 200° for silicon, this increase almost ceases, and the specific heat remains nearly constant. Below 600° the different modifications of carbon give different results, but at and above this temperature they coincide. The constant final values, at the temperatures
above named, for the specific heats of the three elements are as follows: carbon, 0.46; boron, 0.5; and silicon, 0.205. These numbers, multiplied by the atomic weights, give values in accordance with Dulong and Petit's law, so that carbon, boron, and silicon can hereafter be regarded as exceptions only at low temperatures. Dr. Weber's extremely valuable paper concludes with some speculations, based upon his results, as to the nature of carbon, which he thinks may after all prove to be not an element, but a compound.-7 A, March and April, 1875, 161, 276.
A HYDRATE OF CARBON.
Whether or no any true hydrate of carbon can exist has long been an open question. It is now settled affirmatively by Schutzenberger and Bourgeois. These savants treated white cast iron in coarse powder with a solution of copper sulphate, and subsequently with ferric chloride and hydrochloric acid. The metal was thus entirely removed, and a pulverulent, blackish-brown body in small quantity remained. This body was found to be a hydrate of carbon containing eleven atoms of carbon united with three molecules of water. Nitric acid attacked it energetically, changing it into a reddish-brown amorphous substance, which proved to be a new acid of somewhat complicated structure. To this acid the discoverers have given the name nitrographitoic. It also seems to be formed by the direct action of nitric acid upon cast iron.—Bulletin de la Soc. Chimique, May 5, 387.
Frederick Guthrie, in a paper upon "Salt Solutions and Attached Water," has described a curious new series of compounds, which he terms "cryohydrates." He finds that when any saline solution is exposed to a freezing mixture, a crop of crystals after a while separates out, containing the salt plus a definite quantity of water. Thus a saturated brine affords crystals containing one molecule of common salt united with ten molecules of water. Sulphate of zinc, under similar circumstances, forms a cryohydrate with twenty molecules of water; magnesium sulphate with twenty-four molecules, saltpetre with forty-four, sodium sulphate with one hundred and sixty-six, and so on. Similar cryohydrates
are produced with alcohol or with ether in place of a salt. The most important practical feature of Mr. Guthrie's discovery, however, lies in its applicability to the production. of constant, low temperatures. As is well known, water, when passing from the solid to the liquid state, remains steadily at 0° Centigrade until the change is complete. Just so each of these cryohydrates has a constant melting point which can be maintained in any mass of material until the whole is fused. The cryohydrates thus far examined command a range of temperatures from 0° to -28° Centigrade. In order to maintain a vessel at any temperature between these limits, it need merely be surrounded by the proper cryohydrate in a partially melted condition. Then, until either complete fusion or complete solidification of the cryohydrate has occurred, the temperature can not vary.-7 A, January, March, and April, 1875, 1, 206, 266.
DECOLORIZING PROPERTIES Of ozone.
M. Boillot ascribes the bleaching effects, heretofore credited to chlorine, as being really due to ozone. Ozone, employed directly, acts as an oxidizing agent, laying hold of the hydrogen of the substance with which it is in contact, and bleaching it if the body is colored. The action of chlorine. the author explains as follows: On allowing chlorine to act upon any animal or vegetable matter, it decomposes a certain quantity of water, and seizes its hydrogen, forming hydrochloric acid. The oxygen set free by this reaction is transformed into ozone, which in its turn lays hold of the hydrogen of the organic matter.-6 B, May 3, 1875.
NEW FACTS CONCERNING OZONE.
Professor Böttger has succeeded in demonstrating that not only during the decomposition of water, but also on its formation by the union of oxygen and hydrogen, appreciable quantities of ozone are generated. In this connection we recall the fact announced several years ago by Dr. Pincus that ozone is formed during the burning of hydrogen, and that if a jet of this gas issuing from a fine point is ignited, the smell of ozone can be distinctly recognized. In close connection with both of these observations, however, is the discovery previously made by Mr. Loew, and since patented by him,
that ozone may be obtained in sufficient quantity for lectureroom demonstration and other purposes by simply blowing the heated air in contact with the margin of an ordinary Bunsen gas flame, with the aid of a glass tube, into a suitable receiver. If the product thus obtained is then tested with one of the ordinary reagents used for detecting ozone-viz., iodide of potassium, acetic acid, and starch-the blue coloration of the iodide of starch at once appears. At the time Loew's announcement met with some objectors, who sought to explain the phenomenon by assuming that the subsequent reaction was to be ascribed to the formation of small quantities of partly oxidized nitrogen products formed during combustion. The subsequent discoveries of Pincus and Böttger, however, appear to have settled the question by confirming the conclusion of Loew.
CARBONIC OXIDE IN TOBACCO SMOKE.
Dr. Krause has found that tobacco smoke contains a large quantity of carbonic oxide, and he attributes the injurious after-effects of smoking to this poisonous gas, some of which necessarily descends to the lungs, and produces more or less injury. According to Krause, the after-effects are more potent the more inexperienced the smoker, and he ascribes to the carbonic oxide the unpleasant results of the first attempts at smoking rather than to nicotine alone.-12 A, April 6, 1875, 456.
Dr. T. L. Phipson publishes an account of what he calls. mellilotol, as being an acid oil slightly soluble in water, soluble in alcohol and ether, and transformed into mellilotic acid by the action of potassa. It is endowed with most fragrant odor-that of new-mown hay. He obtained it by the distillation of Mellilotus officinalis with water, and isolating from the distillate by means of ether. The plants may gathered while in full bloom, those growing in sheltered places and flowering in August being richer in product. About 0.02 per cent. of pure mellilotol was obtained from the dried plant by distilling the stalks, leaves, and flowers together.
Mellilotol, according to Dr. Phipson, is the starting-point