182 s - HADA; HOW MERCUROUS AXD 



properties of mercurous salts in general, on the authority of Vogel, 

 that sugar boiled with mercurous acetate yields mercury, without 

 mentioning that mercury also precipitates in the absence of sugar or a 

 substitute for it. The fact is that pure cane sugar has no effect. One 

 gram of mercurous acetate was put into lOcc. of water, and one gram 

 of it into lOcc. of a strong solution of sugar ; then both solutions were 

 raised to the boiling point and cooled. Where sugar was absent, .0627 

 gram mercuric sulphide was precipitated after removal of mercurous 

 salt ; where sugar was present, .0612 gram ; in both cases metallic 

 mercury was liberated apparently to the same extent ; the sugar, 

 therefore, had exerted no influence. 



Dissociation of mercurous acetate by light. — It is already known that 

 the acetate among mercurous salts is especially sensitive to light. 

 Some of it was exposed under water in a flask to the sunlight of four 

 days. It was thus strongly blackened, while the solution contained a 

 very evident quantity of mercuric acetate. Another portion kept under 

 water four days in the dark, was scarcely changed in colour. 



Oxidation of mercurous acetate. — Mercurous acetate heated to 150° 

 with water and oxygen in a sealed tube for some hours consumes much 

 of the oxygen with the formation of much mercuric acetate. Only a 

 little metal separates, the confinement of its vapour checking the 

 progress of dissociation. 



Mercury Perchlorates. 



It is only necessary to refer to Chikashige's work on these salts in 

 this laboratory (1895 ; this vol. p. 77) in which it is pointed out that 

 a solution of mercurous perchlorate is obtained when the mercuric salt 

 in solution is shaken with mercury. 



