MERCURIC SALTS CHANGE INTO EACH OTHER. 



181 



converted into mercurous acetate is not mentioned in systematic works, 

 so far as I can find. 



Dissociation of mercurous acetate by heat. — Mercurous acetate so 

 freely dissociates when boiled with water that the mercury not only 

 volatilises with the steam, but collects in globules under the solution. 

 The undissolved part of the salt and that crystallising out on cooling 

 are a mixture of normal and basic mercurous acetates, while the mother- 

 liquor contains much mercuric acetate. Addition of acetic acid at 

 starting does not sensibly affect the dissociation, though it prevents 

 formation of basic salt. 



{Literature and criticism). — It has long been widely known, that 

 mercurous acetate yields a little mercury when its solution is boiled. 

 The first definite reference to this fact seems to be that by Berthemot 

 (1848), given in Gmelin's Handbook, in connection with the prepara- 

 tion of mercurous iodide. No mention of it is made in the Organic 

 Part of the work under mercury acetates, or in Watts's Dictionary, or 

 Morley and Muir's Dictionary, or Beilstein's Organic Chemistry. Berthe- 

 mot quite definitely states that mercurous acetate is partly decomposed 

 by boiling water into mercury which separates and mercuric acetate 

 which dissolves. Allen Miller, in his Elements of Organic Chemistry, 

 (1869), stated that it decomposes into mercury and a sparingly soluble 

 basic acetate, which is unintelligible unless we know that mercuric 

 acetate is also produced. Fresenius in his Quantitative Analysis, 

 mentions that mercurous acetate yields a very little mercury when 

 boiled, but fails to add that it does so in a way quite different from 

 that in which mercurous formate yields mercury, — does not mention, 

 in fact, that mercuric salt is formed in the one case and not in the 

 other. Gmelin, who, as just now said, is silent on the subject in his 

 Organic Chemistry, and correctly states the facts when describing the 

 preparation of mercurous iodide, records in his description of the 



