D. CHEMISTRY AND METALLURGY. 221 



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 hydro- 

 gen. This meteorite is of the stony kind, in which the ox- 

 ides of carbon are the characteristic constituents, while in 

 the iron meteorites hydrogen is most abundant. The spec- 

 trum of the gases evolved from this meteorite, at a few mil- 

 limeters' 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 char- 

 acter of those bodies. 4 D y III., x., 44, July, 1875. 



SOURCE OF THE ACID OF THE GASTEIC 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 pro- 

 duction. One theory supposes that the chlorides of the food 

 are decomposed by the lactic acid which results from the de- 

 composition 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 con- 

 firms 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, accord- 

 ing to the second, the dissociated alkali entering the urine 

 directly Maly sought to decide the question by ascertain- 

 ing 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 experi- 

 ments, 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 re- 

 curred on the formation of lactic acid in the living stomach. 



