IMIDOSULPÏÏONATES (2ND. PAPER). 217 



preceding paper by Hada on Hoiv mercurous and mercuric salts change 



into each other). 



/Hg-NCSCUHg', /Hg''N(S0 3 ) 2 Hg' 2 



The compound, 0< , 0< , 6H 2 



\Hg"N(S0 3 ) 2 Hg' 2 X Hg' 2 N(S0 3 ) 2 Hg' 2 



(atomic ratios; Hg 3 " '. Hg 10 ' '. S 8 ), is obtained by having the mercurous 

 nitrate in excess, about 5 parts being taken for every 2 parts of 

 mercuric sodium imidosulphonate, which provides 7Hg' 2 for every 

 2Hg". The precipitate appears much the same as that obtained when the 

 latter salt is taken in excess, and contains nearly f of the mercuric and 

 imidosulphonic radicals, but only a little more than £ of the mercury 

 of the nitrate used. The mother-liquor is, accordingly, comparatively 

 rich in mercurous salt; it is also acid. Mother-liquor and precipitate 

 are free from sulphate, and the latter from nitrate. The dry precipitate 

 is dull white. 



Calc. Found 



Univalent mercury, 62.89^ ^ 62 - ll \ 7i 



Bivalent mercury, 10.48» 11.46 



Sulphur, 7.22 7.20 



Sodium, — 0.01 



It will now be seen how remarkably the percentages of sulphur 

 and of total mercury approach each other in the two precipitates, 

 widely as the ratio of the two mercury radicals varies. We append 

 the result of analyses of two other preparations; they support the 

 conclusions drawn from the above extremes. 



a B 



Univalent mercury, 59.90; 



J72.78* 73.16f 



i * 



Bivalent mercury, 12.88 



Sulphur, 7.04 7.56 



* This preparation was found to be damp when analysed. 



t The numbers obtained for univalent and bivalent mercury in this case, namely, 51.98 and 

 21.48^, are in accordance with the others, but as they were determined in the salt after it had 

 been hydrolysed, they are unreliable and therefore withheld from the table. 



