1869.] CHEMISTRY AND PHYSICS. 107 



converted into a green oxychlorid, allied in composition to atacor 

 mite, carbonate of sodium being formed at the same time. 

 (C/iem. News, Nov. '27, 1868.) For further observations on the 

 artificial production of oxychlorid of copper, see Dana's Mineral, 

 794. The power of oxyd of lead to decompose chlorid of 

 sodium with the formation of hydrate of soda and oxychlorid of 

 lead, is familiar to chemists. T, s. ii. 



Chromic Iron. — Clouet has shown that when an admixture of 

 protosulphate of iron and sesquichlorid of chromium, in the 

 proper proportions, is precipitated by ammonia, and the resulting 

 oxyds are fused with borax, the compound (Cr2 O3, Fe.^ O2) 

 crystallizes in octohedrous, having the aspect, the hardness, density 

 and chemical indifference to acids which belong to the native 

 chromite, some varieties of which have the formula just given. 



T. s. H. 



Reduction of Nitrates and Sulphates in Certain Fer- 

 mentations. — The reducing action of fermenting organic matters 

 on these salts is well established ; in the case of nitrates, ammonia, 

 and in the case of sulphates, sulphydric acid is formed. According 

 to Bechamp this process is, in all cases, due to the intervention 

 of minute organic germs of a peculiar species, to which he applies 

 the name of Microzyma. These, under ordinary conditions, absorb 

 from the air the oxygen which they require ; but if this source is 

 excluded they take oxygen from the sulphates or nitrates present. 

 These germs are found in the mud of towns, in which sulphid of 

 iron forms, and also in common chalk. Hence, the addition of 

 chalk to solutions of sugar or starch, with sulphate of lime, gives 

 rise to reduction of the salt. t. s. h. 



Effects of Great Cold on Tin.— In a note to the French 

 Academy of Sciences, Nov. 30, 1868, Mr. Fritschzeof St. Peters- 

 burg, described the efiect of intense cold upon ingots of Banca tin 

 weighing from 50 to 60 pounds. The metal had acquired a fibrous 

 structure, and showed fissures like prismatic basalt, besides cavi- 

 ties of considerable dimensions. In this connection Mr. Dumas 

 recalled the brittleness of iron when exposed to great natural 

 cold. T. s. H. 



Analysis of Graphite.— A known weight of graphite in 

 powder is dried between 150° and 180° C, intimately mixed in 



