IMIDOSULPHOXATES (2ND. PAPER). ^15 



Mercurosic imidosulphonates. — Berglund found mercuric potassium 

 imidosulphonate to have no noticeable immediate effect upon a solu- 

 tion of mercurous nitrate, but, on standing, the mixed solutions 

 deposited some oxymercuric imidosulphonate. He must, therefore, 

 have used a solution of mercurous nitrate containing an unnecessary 

 quantity of nitric acid, for, with either reagent used in excess, precipi- 

 tation is immediate, in presence of only a very little nitric acid. 



The precipitate varies in composition with the proportions taken 



of the salts which form it, but still within well-marked limits. The 



variation is very great in the quantities of bivalent and univalent 



mercury, but very small indeed in the quantities of total mercury and 



of sulphur. The composition of the precipitates is such that they 



may be regarded as the oxymercurous imidosulphonate, just described, 



modified in having 1 one-half to three-eighths of its mercurous radicals 



replaced by mercuric radicals, for it varies within the limits expressed 



by the formulae — 



/Hg"N(S0 3 ),Hg' 2 

 0< , 3H 2 



Mlg''N(S0 3 ) 2 Hg' 2 

 and 



/Hg'^CSO^Hg', /BV'NlSO^Hg', 

 0< , 0< , 6H,0. 



\Hg".N (S0 3 ) 2 Hg' 2 \Hg' 2 N(S0 8 ) 2 Hg' 2 



They differ from the purely mercurous salt in having only half as 

 much water of hydration. They cannot be represented as mixtures 

 of the known oxymercurous salt with the known oxymercuric salt. 



The compound, 0[Hg"N(S0 3 ) 2 Hg' 2 ] 2J 3H 2 0— (atomic ratios; 

 Hg", ! Hg' 8 ; S 8 ), is obtained by adding mercuric sodium imidosulphonate, 

 a salt neutral to litmus, to half its weight of normal mercurous nitrate, 

 which makes 3lig" be present for every 2Hg' 2 , and leaves a neutral, or 

 even alkaline, mother-liquor. The mercurous nitrate is used in the 

 form described in the preparation of oxymercurous imidosulphonate. 



