180 S - HADA ; R0W MERCUllOUS AND 



warm, and becomes, for the most part, at least, mercurous phosphate. 



Moist mercurous phosphate is darkened by light. No attempt 

 was made to decompose it by cold water. 



Dissociation of mercurous phosphate by heat. — To obtain a mercurous 

 phosphate free from the nitrate, it was precipitated by adding a solu- 

 tion of mercurous nitrate to a good excess of sodium phosphate in 

 solution acidified with nitric acid, then washed, and dried on a tile. 

 This salt is difficult to decompose into mercury and mercuric phos- 

 phate. However, it does dissociate like other mercurous salts. By 

 boiling it for six hours a small sublimate of mercury was obtained and 

 the mercurous phosphate became pale yellow from the presence of basic 

 mercurous phosphate. The water over it had become quite acid, 

 and contained both mercuric and mercurous phosphates dissolved 

 in phosphoric acid, or as acid phosphates. Eose got similar 

 results, except that the mercury was mixed up with the phos- 

 phates, but not as a sublimate, which does not accord with my 

 experience. Gerhardt observed that mercurous phosphate heated 

 dry becomes mercuric phosphate and mercury, a fact closely related to 

 my subject, though not actually belonging to it. 



Oxidation of mercurous phosphate. — Heated at 150° in oxygen, mer- 

 curous phosphate was oxidised much to the same extent as the 

 sulphate. 



Mercury acetates. 



Conversion of mercuric to mercurous acetate. — A cold dilute solution 

 of mercuric acetate shaken violently with much mercury is readily and 

 at once converted all into mercurous acetate. According to Lefort 

 (1845 ; Annalen, 56), this conversion needs long boiling ! I do not 

 hesitate to say that long boiling would never complete it, so easily does 

 mercurous acetate dissociate. The fact that mercuric acetate can be 



