THE IMIDES OF THE AROMATIC SULPHONIC ACIDS. 21 



The anhydrous substance, dried in a vacuum desiccator, melted 

 at 132°C. and, on analysis, gave the following results : — 



KÖXIGS gives the melting point of the substance as 109°C. (loc. 

 cit.). His preparation was obtained by crystallisation from 

 alcohol and, therefore, probably retained some alcohol of crystal- 

 lisation, but he never seems to have recognised this possibility. 

 More recently, Angeli, Axgelico and Scurti gave the melting 

 point as 126°C. (Chem. Central-Blatt, 1902, II, 092). The 

 author can not find, at present, any adequate explanation of the 

 discrepancy. 



When an alcoholic solution of dibenzenesulphohydroxylamine 

 is poured into an excess of water the substance is precipitated in 

 the form of microscopic crystals, containing two molecules of water 

 of crystallisation. 



Found Calc. for (CoH.SO,) ,XüH,2[I,0 



Sulphur 18.27 18.36 



Dibenzenesulphimide (CgH5S02)2NH. 



When crystallised from water this substance forms thick 

 prismatic crystals, consisting largely of twins. It contains water 

 of crystallisation and is slightly efflorescent. The quantity of 

 water was ascertained from loss in weight on heating at 10-5-1 10°C., 

 the crystals having been previously powdered and air-dried. Two 

 preparations were analysed and they yielded somewhat discordant 

 results. In the one case, the loss was found to amount to 8.07 

 per cent, while in the other it was found to be 7.85 per cent. The 



