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.

CRYOHYDRATES.

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 OFf 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.

MELLILOTOL.

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 be 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

of a great variety of very interesting compounds, and it yields, as before stated, mellilotic acid, which in its turn yields coumarin. It is mellilotol, and not coumarin, which is the cause of the odor of new-mown hay and of that of the flowers of the Mellilotus.-1 A, July 16, 25.

MANUFACTURE OF ARTIFICIAL VANILLA.

It is not long since Messrs. Tiemann and Haarmann, students of Dr. Hofmann, of Berlin, made the discovery that vanillin, or the aromatic principle of the vanilla bean, can be obtained from the sap of the pine. These gentlemen have now completed their operations for going into the manufacture of the article on a large scale, as they find that the sap of an ordinary tree will furnish vanillin of the value of $20, without in the least injuring the wood for timber. Dr. Hofmann, in communicating these facts to the Academy of Sciences of Paris, remarks that this is the second vegetable product manufactured by purely chemical methods.-12 A, September 24, 1874, 427.

HYDROGENIZED IRON.

Cailletet states that in his experiments on the passage, at ordinary temperatures, of hydrogen through iron, he has found that on allowing sulphuric acid to act upon a plate of iron, the hydrogen is, in part, absorbed by the metal, and that, by employing a system formed of two plates of iron soldered side to side, he finds the tension of the gas which accumulates in the apparatus is equal to a column of mercury 0.35 millimeter high. As the result of his investigations into this combination of iron and hydrogen, he says that this iron gives up, under water or other liquid, numerous bubbles of a gas which is pure hydrogen. In the open air the galvanic iron loses only a part of the hydrogen which it has occluded. When a piece of hydrogenized iron is brought near a burning body the hydrogen is rapidly disengaged, and the metal is surrounded by a light-blue flame. When the iron has lost by heat the hydrogen which it contained, one can not restore that gas to it. Employing a piece of iron that had been so heated as a negative electrode, Professor Cailletet found that the water is decomposed and the hydrogen disengaged as usual in abundance;

K

but the hydrogen does not again become occluded in the iron plate. Hydrogenized iron can be easily pulverized, but after it has been heated it retains a certain ductility. Hydrogen, in associating itself with the iron, communicates to it considerable magnetic force, so that the presence of hydrogen in iron modifies greatly the magnetic properties

of this metal.

MICROSCOPIC EXAMINATIONS OF THE PROCESS OF CRYSTAL-
LIZATION.

Professor Frazer, Jr., exhibited to the Academy of Natural Sciences of Philadelphia a combination of the polarizer, vertical lantern, and microscope, by means of which the manner in which different salts crystallize out of their solutions, together with the manner in which they affect polarized light, can be explained and illustrated. The light from a lime lantern is passed through a rubber tube polarizer, then upward through the vertical lantern and a twoinch lens microscope, when it is again reflected horizontally on the screen. He explains that while this method has the advantage of so magnifying the crystals produced from small quantities of solutions that their structure can be minutely observed, as well as the sudden molecular change which causes the polarizing effect, it is open to the objec tion of a very large loss of light, first by the polarizer, and again by the microscope. A part of this difficulty, however, can be obviated by the use of the parabolic reflector.-Proc. Acad. Nat. Sci., Phil., 1875, 16.

A BRITTLE ALLOY OF IRON AND HYDROGEN.

Mr. Johnson communicates to Nature some important observations in reference to the action of hydrogen on iron and steel. Experiments made by him have shown that any acid which gives off hydrogen, when it is allowed to act upon iron or steel, produces the same effect, viz., of depriv ing the metal of its original toughness, and gives it the property of frothing when moistened with saliva. The gas coming off the surface of the iron, if cold, is shown to be hydrogen; and it seems probable that the brittleness of the metal is due to the occlusion of hydrogen within the iron. The simplest way of charging a piece of iron with hydrogen