How Mercurous and Mercuric Salts change 

 into each other. 



By 

 Seihachi Had a, Rigakushi. 



College of Science, Imperial University. 



Notwithstanding all that has been done and observed about the 

 passage of mercurous salts into mercuric, and, conversely, of these into 

 mercurous salts, in the absence of specific oxidising and reducing 

 agents, or, as we are apt to say, ' spontaneously,' the subject seemed 

 to call for a comprehensive investigation, which should serve to 

 establish the way or ways in which these changes come about. 



It is rare to meet with a definite general statement on the 

 subject. MendeléefFs Principles of Chemistry contains one which runs 

 as follows : " The mercurous compounds under the action of oxidising 

 " agents, even air, pass into mercuric compounds, especially in the 

 " presence of acids, but the mercuric compounds when in contact with 

 " mercury, change more or less readily, and turn into mercurous 

 " compounds " (vol. ii, p. 50). Another occurs in Gmelin-Kraut- 

 Jörgensen's Handbuch (not Grmelm-Watts'), which is to the effect 

 that water " decomposes mercurous salts in the heat into metal and 

 mercuric salts," and one similar is to be found in Menschutkin's 

 Analytical Chemistry. These sentences express probably the current 

 belief of chemists ; to what extent they are sufficient and accurate will 

 appear in this communication, except as to the effect of oxidising 

 agents other than air, upon which I have nothing to say. 



The work now to be recorded proves the truth of two propositions 

 as to the nature of the changes of mercurous and mercuric salts into 



