IQQ DIVERS AND HAGA. 



salt, which was to have the formula, 0[FIgN(S03]sra)2]2, analogous to 

 the oxynitrate, 0(HgN03)2, we got, instead, only the other two salts, 

 one in solution, the other as a precipitate. The oxymercuric sodium 

 salt was thus obtained from a liquor which from first to last was 

 never acid, even the mother-liquor being still faintly alkaline. The 

 sulphonate and nitrate were used in the proportions — 2Na]Sr(S03]S[a)2 

 to Hg(N 0.3)2 ; the nitrate was added gradually, with stirring, to 

 the dilute solution of the sulphonate, and simultaneously a solution of 

 sodium hydroxide run in in the proportion of nearly five-sixths of a 

 molecular quantity. By this procedure, much yellow mercuric oxide 

 was formed along with the white precipitate, but by prolonged stirring, 

 the precipitate lost all tinge of yellow. The mother-liquor now con- 

 tained much disodium mercury imidosulphonate, and the precipitate, 

 washed and drained on a tile, ])roved to be pure oxymercuric sodium 

 imidosulphonate (analysis, d). Allowing for sodium hydroxide used 

 in neutralising the free nitric acid present in the mercuric-nitrate 

 solution, the reaction appears to be that expressed by the equation : — 



6NaN(S03Na)2 + 6Hg(N03)2 + 4NaOH= 

 = 2HgN2(S03Na),-fHg(OHgS03)2NHgN(S03Na)2-t-12NaN03+2H20. 



Oxymercuric sodium imidosulphonate contains water of crystal- 

 lisation and appears to be a little efflorescent ; otherwise, it is for a 

 long time permanent, wet or dry, though ultimately becoming yellow- 

 brown })y decomposition. Protracted washing with water decomposes 

 it, as does als(3 digestion with concentrated mercuric-nitrate solutions, 

 a residue being left in both cases, which is the hydrogen oxymercuric 

 salt (p. 97 ). It is very stable when but moderately heated, only 

 losing its water, with the exception of a very little. At about 1 35" 

 it permanently changes colour shghtly, and at a much higher tempera- 

 ture melts to a dark red-brown liquid and effervesces, decomposing in 



