IMIDOSULPHONATES (2ND. PAPER). 199 



still more ainmoniated salt, Ba 5 (NH 4 ) 2 (NS 2 6 ) 4 , 8H 2 0. All these 



double salts of barium are granular and powdery, and quite unlike the 

 peculiarly soft, clinging, pure barium salt. 



Strontium imidosulphonales. 



According to Berglund, normal strontium and normal calcium 

 imidosulphonates are in properties, water of crystallisation, and 

 conditions of formation, as like each other as two salts can be, but unlike 

 the normal barium salt. This account of the normal salts puzzled us, 

 but when we found his description of the properties and way of 

 preparation of the calcium salt applies perfectly, so far as it goes, to a 

 salt, described by us in our first paper, which we had found to be 

 calcium sodium imidosulphonate, we lost all confidence as to the 

 accuracy of his account. We therefore studied the strontium salts for 

 ourselves, having omitted to do so before, when preparing our first- 

 paper. 



Normal strontium imidosulphonate, according to Berglund, 

 gradually separates in acicular prisms when a solution of strontium 

 chloride, moderately concentrated, is mixed with one of either normal 

 sodium imidosulphonate, or of diammonium imidosulphonate to which 

 ammonia has been added. Its composition is expressed by Sr 3 (NS 2 6 ) 2 , 

 6H 2 0, and it loses by heat, even at 130° — 140°, only two-thirds of its 

 water. In preparing it, it is unnecessary, he said, to take any 

 care to have the strontium chloride in excess, although it is very 

 important to keep the barium chloride in excess when preparing the 

 normal barium imidosulphonate. 



Normal strontium imidosulphonate, according to our experience) 

 cannot be obtained by mixing together strontium chloride and normal 

 sodium imidosulphonate, but always strontium sodium imidosulpho- 

 nate. But from tins sail it can be obtained just in the same way as 



