48 i P. C. Ray — Mercurous Nitrite and its Derivatives, [No. 4, 



along in the shape of the nitrites of the respective metals, in other words, 

 there ivas no change in the radical N0 2 . 



B. Dilute solutions of silver and mercurous nitrite, {vide Exp. 



5 and 6 in the Table of Results of Analyses). 



It is worthy of note that under such conditions of dilution no 

 silver was precipitated. 



C. Mercurous Nitrite and Sodium Nitrite. 

 In this case also the total amount of nitrogen remained constant, 

 and in the shape of nitrites, the only difference being that the mer- 

 curous nitrite was completely transformed into mercuric nitrite with 

 precipitation of mercury. In Exp. 7 a 6°/ solution of sodium nitrite 

 was used. Sodium nitrite was, however, found to have scarcely any 

 action on very dilute solutions of mercurous nitrite. 



Discussion of Results. 



It is not easy to enter into the mechanism of the reaction of mer- 

 curous and silver nitrites, when it is remembered that there is no 

 change in the radical N0 2 . Mercurous nitrite, it is true, has already 

 been shown to undergo partial dissociation according to the equation, 



Hg 2 (N0 2 ) 8 =Hg (N0 2 ) 2 + Hg. 

 when in solution ; but the reaction, we are at present studying, can 

 scarcely be brought under the same category. At the same time, it 

 must be admitted that, if we were to regard for a moment a molecule of 

 silver nitrite playing the role of a molecule of mercurous nitrite, all 

 the equations under A. could be established on a common basis. 



For instance in Exp. 1, 3 HgN0 2 +A.gN0 2 may be regarded as 

 equivalent to 4 Hg N0 2 , i.e., 2 Hg 2 (N0 2 ) 2 which may be expected to 

 dissociate as follows : — 



2 Hg 2 (N0 2 ) 2 = 2 Hg (N0 2 ) 2 +2 Hg [or Hg + Ag]. In Exp. 3, 7 Hg 

 N0 2 + 3 Ag N0 2 would similarly be equivalent to 10 Hg N0 2 i.e., 5 Hg 2 

 (N0 2 ) 2 which would dissociate thus : 5 Hg 2 (N0 2 ) 2 = 5 Hg (N0 2 ) 2 + 5 Hg 

 [or 2 Hg + 3 Ag], with this difference, that in place of 2 Hg we 

 get Hg + Ag, and in that of 5 Hg we get 2 Hg + 3Ag. In Exp. 5 and 



6 bracketted together under B., where dilute solutions of both the 

 nitrites were used, and where there was no precipitate of metallic 

 silver, the nitrite of silver apparently seems to take no part. The 

 same remarks would also apply to Exp. 7 and 8 (vide Table of 

 Analyses), where sodium nitrite also appear to act catalytically, an 

 expression conveniently used to cover ignorance. The true explanation 

 of the reaction has yet to be found out, and with this view, it is intended 

 to take up another series of experiments under various degrees of 

 dilution of the nitrites. 



