98 



DIVERS AND H AG A. 



and comparatively stable liquors, solid potassium or sodium imidosul- 

 phonates. When sufficiently he;ited these liquors allow the imidosul- 

 phonate to hydrolyse into amidosulphonate, but ^^'hen, without heating, 

 they are diluted, they deposit oxy mercuric hydrogen imidosulphonate. 

 The same salt is almost immediately precipitated when tri.sodium 

 imidosulphonate in solution is added to mercuric nitrate. 



To prepare this salt take about five parts l)y weight of mercuric 

 nitrate solution, undiluted and equal to about half its weight of mere 

 curie oxide, and pour into it with stirring a cold solution (necessarily 

 dilute) of one part of trisodium imidosulphonate. Precipitation of th- 

 snlt begins almost at once and is finished in a few minutes. The 

 mother-liquor contains still nuich mercuric nitrate and some imidosul- 

 phonate, besides sodium nitrate and much nitric acid. Addition of a 

 little more trisodium salt causes scarcely any more precipitation, while 

 that of a large quantity throws down the oxymerciu-ic sodium salt. 

 The brilliant w^hite and voluminous oxymercuric hydrogen salt hydro- 

 lyses only very slowly in its acid mother-liquor, because of the in- 

 hibitory action of the mercuric nitrate. It is to be washed repeatedly 

 by subsidence and décantation with abundance of cold water and 

 drained till dry on a tile or filter. Where less mercuric nitrate has 

 been taken, and the precipitate contains sodium (as oxymercuric 

 sodium salt), either digestion for a, day with concentrated mercuric 

 nitrate solution and washing, or else, without use of mercuric nitrate, 

 continued and thorough washing with water will convert the 

 precipitate into the ])ure oxymercuric hydrogen salt. After digesting 

 with the mercury nitrate, the first washing waters used must con- 

 tain a, little nitric acid to guard against the formation of any 

 oxynitrate. 



Oxymercuric sodium imidosulphonate when long washed with 

 much water leaves a much smaller weight of oxymercuric hydrogen 



