2 AUT. 1. — E. DIVERS AND M. OGAWA : 



There is left a mottled orange mass, of waxy consistence, already 

 described in the earlier paper (loc. cit., p. 196), which is difficult 

 to attack with solvents other than water, because it adheres very 

 firmly to the vessel and must not be exposed to the air during 

 treatment. By protracted digestion with successive portions of 

 90 per cent, spirit, aided by scraping with a pointed glass rod 

 and strong shaking, it can however be nearly all dissolved up 

 although only very sparingly soluble. The first portions of the 

 solution are coloured and contain a salt the presence of which 

 interferes with the preparation of the imidosulphite from them. 

 The later colourless extracts yield the imidosulphite when they are 

 evaporated, in the vacuum desiccator but not quite pure. Much 

 better results are got by beginning the treatment with warm 95 

 per cent, spirit, used in successive portions, until the residue is 

 a colourless powder, and only then resorting to the 90 per cent, 

 spirit and carrying on the digestion at about 50°. The solution 

 thus obtained deposits almost pure imidosulphite as it cools, 

 and the mother-liquor can be used with advantage again and 

 again to dissolve out more of the salt, although in that case the 

 crystals which separate are somewhat impure. These can be 

 purified by washing with absolute alcohol containing much ammonia 

 to dissolve out the foreign salt (more soluble in presence of am- 

 monia), and then dissolving up in warm 90 per cent, spirit and 

 recrystallising. The original mother-liquor yields more imidosul- 

 phite, but impure, when it is either artificially cooled (as by ice 

 and salt), or is evaporated in the desiccator. This impure salt 

 can be purified in the way just described. All the ammonium 

 imidosulphite is finally washed with ammoniacal alcohol, drained 

 on a porous tile under close cover, and dried in a potash-desiccator. 

 The quantity of pure salt actually obtained in this way approaches 



