74 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Cuprous Sulphate. — A. Recoura has succeeded in prepar- 

 ing this hitherto unknown salt, Cu 2 S0 4 . Two complex com- 

 pounds of the salt, Cu 2 S0 4 .2CO.H 2 and Cu 2 S0 4 .4NH 3 had been 

 prepared previously, but when attempts were made to remove 

 the carbon monoxide or the ammonia from these compounds, the 

 cuprous sulphate was decomposed at the same time. The reason 

 for previous failures to prepare cuprous sulphate lies in the fact 

 that the compound is instantly decomposed by water, and it has 

 at last been prepared by the action of an anhydrous reagent, 

 methyl sulphate, upon cuprous oxide. The reaction produces 

 gaseous methyl ether as indicated by the equation Cu 2 -f (CH 3 ) 2 

 S0 4 =Cu 2 S0 4 + (CH 3 ) 2 0. The reaction can be carried out with 

 great ease by heating finely pulverized cuprous oxide with a 

 large excess of methyl sulphate in a flask to 160° C. No precau- 

 tions for the exclusion of air are necessary, but the heating 

 should be stopped as soon as the evolution of gas has ceased, for 

 otherwise a second reaction sets in whereby the product is 

 changed to cupric sulphate by the action of the methyl sulphate. 

 The product is a grayish white powder which is perfectly stable 

 in dry air. It is only slowly attacked by moist air under ordi- 

 nary conditions, but when it is wet with ether and the ether is 

 allowed to evaporate in the air, it is oxidized with great rapidity, 

 in a peculiar way, forming a mass as black as soot. This black 

 oxidation product when treated with water appears to yield the 

 black oxide Cu 4 0, which has been described by Rose, and cupric 

 sulphate. The unoxidized salt gives with water cupric sulphate 

 and metallic copper, a reaction which yields a disengagement of 

 heat amounting to 21 calories. This thermochemical relation is 

 opposite to that existing between cuprous and cupric oxides, 

 chlorides and sulphides, where the cuprous compounds are formed 

 exothermically. — Comptes Mendus, cxlviii, 1105. h. l. w. 



2. The Action of Hydrogen Antimonide upon Dilute Silver 

 Solutions. — The familiar precipitate formed when hydrogen anti- 

 monide is passed into a silver solution is usually regarded as Ag 3 Sb, 

 formed according to the equation H 3 Sb -MAgNO^AggSb-f- 

 SHNOg. A number of investigators, however, have been led to the 

 conclusion that the reaction is more complicated than the one 

 represented hj this equation. H. Reckleben has recently made 

 a careful study of this reaction, and has found that in the first 

 place silver antimonide, Ag a Sb, is formed according to the above 

 equation, but that this precipitate then reacts to a considerable 

 extent with the excess of silver nitrate as follows : 



Ag 3 Sb + 3AgN0 3 + 3H 2 = 6Ag + H 3 Sb0 3 + 3HN0 3 . 



