23. 



Notes from the Chemical 

 College* Note No. 3. 



•i« 



Mercuroso-Mercu 



ric Nitrate. 



By P. 0. R\y, 



It has already been shown that mercurous nitrite when 

 treated with water, undergoes partial dissociation. But however 

 much the solution may be diluted, about 22 per cent of the salt 

 dissolves without decomposition.* The explanation of this anoma- 

 lous behaviour lies in the fact that in solution a pretty stable 

 compound 4Hg (1^02)2 + 2 (Hg NO^) is formed. If, however, 

 an alkaline nitrite or even silver nitrite be added to the above 

 solution, the mercurous nitrite is completely dissociated into 

 mercury and mercuric nitrite (vide Journ. Asiatic Soc. Bengal^ 



Ixix., pt ii, 1900, p. 413). 



Recently I have been engaged in a systematic investigation of 

 this subject. A large excess of mercurous nitrite was triturated 

 in a mortar with silver nitrite, and water was added from time to 

 time. The liquid, which looks dirty grey due to the suspension 

 of metallic mercury in a fine state of division, on filtration gave a 

 clear, pale-yellow solution- It was then allowed to evaporate 

 under diminished pressure over sulphuric acid. After a few days 

 a bright yellow, crystalline powder was obtained. The compound 

 proved to be silver-mercuroso-mercuric nitrate. The analysis of 

 a typical preparation is given below : 



Mercuric mercury Hg'' 

 Mercurous mercury Hg' 

 Silver A^r 



Nitrogen N 



• • • 



• « » 



26-23-=- 200 =01312 

 45-81-T-200 = 0-2290 j 



4J5-r-108 = 0- 

 3-60-=- 14 = 0-2570 



0-2670. 



The simplest ratio is Hg" : (Hg'+Ag): N-1: 2: 2. 

 Hence the formula of the componnd would be Hg" (Hg', Ag)^ 



It has already been shown that when the solution of mercu- 



roso 



nitrite is allowed to 



p orate 



basic mercuroso-mercuric nitrate m the shape of a yellow crystal- 

 line powder is obtained (Trans. Chera. Soc, 87, 1905, 174), the 

 nitrite undergoing decomposition thus, 



3Hg N02=Hg,0 + HgNOg + 2NO. 



I Joura, Asiatic Soc. Bengal, Iit. pt. ii- (1896), p. 1, 



