is by laying it on a sheet of zinc in a basin of diluted sulphuric acid. The hydrogen generated by the action of the acid on the zinc is given off on the surface of the iron; and two minutes or less will suffice to charge a piece of iron with hydrogen, and alter its properties completely. This alteration is not confined to a diminution of toughness, which may be reduced to one quarter of its original value, but is also accompanied by a marked decrease in tensile strength, amounting in cast steel to upward of twenty per cent.; but in the case of iron-ware to only six per cent. The electrical resistance is increased by this occlusion of hydrogen. It is probable that repeatedly rusting iron occludes hydrogen, and it is thereby deteriorated in strength and toughness.-Nature, II., 903.

THE COMPOSITION OF BLEACHING-POWDER.

The question of the composition of the so-called" chloride of lime" has lately been much agitated. The generally received view of Gay Lussac, that it is a true calcium hypochlorite, has been attacked by Goepner, who regards it as merely a molecular compound of lime and chlorine, containing no hypochlorous acid. Mr. Ferdinand Kopfer now submits the subject to the test of a long series of careful experiments, and decides in favor of the old view. He finds that when a dilute mineral acid, just sufficient to saturate the calcium present, is added to a solution of bleaching-powder, no smell of free chlorine can be detected, but only the characteristic odor of hypochlorous acid. The solution thus obtained, shaken up with a large excess of mercury, yields the brown oxychloride of the metal, again proving the presence of hypochlorous acid.-Jour. Chem. Soc., August, 1875.

THE INCOMPLETE COMBUSTION OF GASES.

The habilitation thesis of Dr. Ernst Meyer on the incomplete combustion of gases contains the following suggestive sentences: The studies upon inflammability, which, according to the experiments contained in this essay, stand in a closer connection with the phenomena of affinity than we should at first suspect, indicate the importance that must be attributed to the thermal relations of the gases. The combustion of carburetted hydrogen in a closed tube, which, be

ginning with the overleaping of the limits of inflammability, and with increasing quantities of oxygen, exhibits a series of different steps, until finally, by its total combustion, we reach an invariable final result, exhibits many interesting passages. Simple as is the result of the complete combustion, the incomplete combustion is exceedingly complex. If a mixture of carburetted hydrogen with oxygen approaches the limit of inflammability, then, in general, the steps of the combustion are exceedingly complicated. In this case the strong affinity of carbon for oxygen is shown, in that the latter at first serves exclusively to form carbonic oxide. When the hydrogen begins to take part in the burning, then there becomes evident, as we recognize from the compound nature of the resulting mixture of gases, an effort to establish an equilibrium according to the properties of the molecules. Similarly, under simpler conditions, in the case of the incomplete combustion of a mixture of carbonic oxide and hydrogen, the burning gases arrange themselves according to their molecules; and the same regularity holds in the complicated processes of the combustion of carburetted hydrogen, while in the latter the play of the af finities of carbon and hydrogen in general is easily recognized. Although we can not obtain clear views concerning their relative proportions, still the observations which are here given form definite starting-points for further considerations. These simplest processes will, perhaps, assist in the solution of problems of the highest importance in the mechanical explanation of the phenomena of chemical affinity. Precisely those conditions which variously affect the affinity of hydrogen and carbonic oxide, and which, as we may assume, may be referred to the different friction of the gases, point to causes which must be sought in the moving molecules themselves. A thorough study of such modifying circumstances will certainly advance our knowledge of the nature of chemical affinities.-Habilitations Schrift, Leipzig,

1874.

GASES OCCLUDED IN METEORITES.

The meteorite that fell on the 12th of February, 1875, in Iowa, has been examined chemically by Professor Wright, of New Haven, who has shown that in the gases contained

within it there was a great predominance of the carbon compounds, which were plainly indicated by spectroscopic analysis; and by careful quantitative analysis it was found that 49 per cent. of the occluded gases were carbonic acid and carbonic oxide; the residue consisted largely of hydrogen. This meteorite is of the stony kind, in which the oxides of carbon are the characteristic constituents, while in the iron meteorites hydrogen is most abundant. The spectrum of the gases evolved from this meteorite, at a few millimeters' pressure, gave brilliant carbon bands; the brightest were the three in the green and blue, the red only being much feebler; agreeing in this respect remarkably with the spectrum of some of the comets, and affording a decided confirmation of the received theory as to the meteoric character of those bodies.-4 D, III, x., 44, July, 1875.

SOURCE OF THE ACID OF THE GASTRIC JUICE.

The theories which have been proposed to account for the acidity of the gastric juice agree that this acidity is due to hydrochloric acid; but they differ as to the mode of its production. One theory supposes that the chlorides of the food are decomposed by the lactic acid which results from the decomposition of the carbohydrates ingested; the other that these chlorides are decomposed by simple dissociation. To test these theories, Maly has made a series of experiments, mainly upon dogs, but also upon the human subject. He confirms Bence Jones's observation that the acidity of the urine is diminished during the secretion of the gastric juice, being a minimum when the digestive process reaches its maximum activity. But as this fact may be accounted for on either theory-according to the first the lactates produced being oxidized to carbonates, and so entering the urine, and, according to the second, the dissociated alkali entering the urine directly-Maly sought to decide the question by ascertaining whether chlorides could be decomposed by lactic acid. Sodium chloride and lactic acid, when distilled, gave only at the last traces of hydrochloric acid. But diffusion experiments, in which lactic acid was mixed with sodium, calcium, magnesium, and ferrous chlorides, showed that hydrochloric acid was formed in dilute solutions. The question then recurred on the formation of lactic acid in the living stomach.

Fragments of the mucous membrane of the stomach of the pig were digested at 40° Centigrade with two per cent. solutions of grape sugar, cane sugar, milk sugar, and dextrin. Lactic acid was formed, but the process was stopped at 100° Centigrade. Gastric juice, however, used in place of the membrane, produced no such effect. From the fact that an abundance of bacteria were developed at the same time, Maly considered it quite clear that the formation of lactic acid results from an organized and not from a chemical ferment; and therefore that the production of lactic acid is not a function of a living membrane. This view is strengthened by the fact that the fresh stomach of a dog, when digested with a two per cent. solution of grape sugar, gave no acid until after two days. Moreover, the stomach of a living dog was emptied, milk of magnesia introduced, withdrawn after an hour, and the magnesia dissolved determined; then the sugar solution was introduced with the magnesia, and the experiment repeated. The same amount of dissolved magnesia was found in both cases, showing that the living membrane does not cause the formation of lactic acid from sugar. The author maintains, therefore, that free lactic acid is absent from gastric juice, and that hence, à fortiori, it does not decompose chlorides to set free hydrochloric acid. The source of this latter acid in the gastric juice the author believes to be dissociation.-33 C, CLXXIII., 227.

DECOMPOSITION OF CHLORAL HYDRATE IN THE SYSTEM.

It was assumed by Liebreich, the discoverer of the pecul iar physiological action of chloral hydrate, that this substance, under the influence of the alkaline blood-serum, was decomposed, yielding chloroform. Tanret has shown, however, that if a solution of chloral hydrate be mixed with an alkaline solution of potassium permanganate, the liquid is decolorized, a gas is evolved, and manganic oxide is precip itated. If the quantity employed be considerable, and the temperature be kept from rising above 40° Centigrade, the reaction is slow, and the filtered liquid will be found to contain chloride, carbonate, and formate of potassium. The gas evolved is carbonous oxide. The same reaction can be ef fected in very dilute solutions, and takes place even when the alkalinity is produced by borax. From these data the

author proposes a new theory to account for the action of chloral hydrate in the animal economy. When taken into the body, it is not only submitted to the alkaline serum, but to oxidizing agencies at the same time. Both these causes taken together effect its decomposition in the manner above described, carbonous oxide being set free in the blood, displacing its oxygen and producing symptoms analogous to those observed in cases of poisoning by this oxide of carbon. Moreover, the lowering of the temperature of the body, which is observed in these cases, and the prolonged action observed with chloral hydrate, combine to render this hypothesis more tenable than the old one. Fatal poisoning by chloral hydrate is not at all an impossible thing, therefore, if these facts be true.-6 B, LXXIX., 662.

GALLIUM, A SUPPOSED NEW CHEMICAL ELEMENT. Lecoq de Boisbaudran announced to the French Academy, on the 27th of August, that he had discovered a new chemical element in a blende from the Pierrefitte Mine, valley of Argèles, Pyrenees. Its chemical reactions resemble those of zinc, but it differs from this metal in being precipitated as oxide by zinc, and also by the following facts: That its chloride is precipitated by ammonia; that its oxide is soluble. in an excess of ammonia; that its sulphide is precipitated by ammonium sulphhydrate, and is insoluble in excess of the precipitant; that this sulphide is thrown down in presence. of acetic though not of hydrochloric acid; that barium carbonate precipitates it even in the cold; that the chloride is not volatile; and that when the solution containing zinc is heated up to the point of production of oxychloride, all of the new substance remains insoluble. In a subsequent paper presented to the Academy a month later, the author proposes the name Gallium for the new metal, and gives more complete statements of its spectroscopic characters. In concentrated solution, it gives with the electric spark a spectrum. containing two prominent lines. One of these is a moderately bright violet line of wave-length 417. The other is fainter, and has a wave-length of 404. The chloride gives the line 417 in the ordinary gas flame.-6 B, LXXXI., 493, Sept., 1875.