g4 DIVERS AND HAGA. 



abundant white sublimate and, what is of in<jre «ignificance, the nitro- 

 o'en. Had either done so, it would then have been seen that the salt 

 is not an addition compijund of ammonia, as they supposed. 



One of the remarkable properties we find imidosulphonates, as 

 also oxiniidosuiphonates, to possess, is that of hydrolysing at a suffi- 

 riently high temjjerature by fixing the moisture of the air. Claus had 

 observed slow increase in weight of ])otassium nitrilosulphonate and in 

 oximidosul]>hon;ite (his trisulphammonate and disulphydroxyazate) 

 when they \Nere heated in the air, but wrongly ascribed tliis increase 

 to oxidation. Oxidation it could not be, for this would (jnly give rise 

 to volatile products, such as water, or oxide of nitrogen, or nitrogen 

 itself, and not increase the weight of tlie fixed matter. We have, be- 

 sides, fuUv j)roved by experiment that at the temperature, or at a highei- 

 one than that even, at which any imidosulphonate increases in weight 

 in ordinarv air, that salt remains for hours unchanged in w^eight and 

 appearance in a current of dried air, and yet is ready, when exposed at 

 the same temjjerature to undried air, to begin increasing in weight. 

 By the hydrolysis in ordinary air an imidosulphonate loses crystalline 

 lustre, cakes together, and becomes acid. Salts, such as the disodium 

 imidosulphonate, which contain water of crystallisation, i-equire slow 

 drying at a gentlv rising temperature t(3 prevent hydrolysis, and even 

 then are difficult to dehydrate, Di])otassium imidosulphonate, the 

 crystals of wliich are anhydrous, is particularly stable and may be 

 heated for hours to 140° or higher in undried air, without the 

 least sensible change. But at 170-180° it slowly fixes water and 

 hydrolyses. 



As the tripotassium imidosulphonate is mucli more soluble than 

 the dipotassium salt the latter dissolves readily in potassium hydrox- 

 ide scjliition, from which it can be precipitated by carbonic acid 

 (llaschig). Other and new reactions of the dipotassium salt, observed 



