THE IMTDES OF THE AROMATIC SULPHONTC ACIDS. 3 



barium hydroxide and the crystals of barium dibenzenesulphimide 

 were, as much and as pure as possible, obtained by repeated 

 evaporation and crystallisation. From the weight of the barium 

 dibenzenesulphimide thus obtained, the yield of the imide was 

 calculated to be 73.8 per cent of the theoretical amount. Two 

 more similar experiments, made with sixty and twenty grammes 

 of dibenzenesulphohydroxylamine dissolved in common alcohol 

 and treated Avith a quantity of sulphur dioxide equal to about five- 

 sixths of the weight of dibenzenesulphohydroxylamine taken, gave 

 74 and 83 per cent, respectively, of the theoretical amount of 

 dibenzenesulphimide. As the yields of dibenzenesulphimide were 

 in these experiments somewhat below the theoretical, it appeared 

 probable that alcohol entered into the reaction and, in some 

 way, more or less interfered with the formation of the imide. 

 With view to ascertaining if this was really the case, the following 

 experiment was made. 



About eight grammes of dibenzenesulphohydroxylamine in the 

 finely powdered state were suspended in about two hundred and 

 seventy cubic centimetres of water and treated with sulphur 

 dioxide, until the increase in weight was about thirteen grammes, 

 and then left in a tightly stoppered bottle, with occasional 

 stirring, until the substance had completely disappeared, which 

 required about five days. The excess of sulphur dioxide was 

 then blown off by a current of air. The whole was neutralised 

 with barium hydroxide and concentrated after filtering off the 

 barium sulphate. By crystallising out as much of the barium 

 dibenzenesulphimide as possible, by repeated concentration and 

 crystallisation, a yield of 71.1 per cent of the theoretical amount 

 was obtained, which is even smaller than the yield in the previous 

 experiments when alcohol was used. The barium sulphate above 



