200 EDWARD DIVERS AND MASATAKA OGAWA : 



coloured impurity (apparently nitrogen sulphide) and ammonium 

 sulphite. 



After passing the sulphur dioxide in for a short time, the 

 turhid solution produced had to he allowed to clear and then 

 he decanted, with as little exposure to air as possible, from 

 a small deposit (0.5 grm. or less) of anhydrous ammonium 

 sulphite, into another reaction-flask. This sulphite represented 

 the small amount of moisture carried into the alcohol by the 

 ammonia or otherwise. The introduction of sulphur dioxide 

 being resumed, transparent four-sided prisms began to form 

 when the ammonia was nearly saturated, and then so rapidly 

 increased in quantity as to have dried up nearly all the solu- 

 tion by the time the ammonia was all gone. If at this point 

 the operation was arrested and the flask brought to the common 

 temperature and placed in a vacuum-desiccator, it was found 

 to be impossible to get the crystals pure enough for analysis, 

 because there was not only the liability of this exceedingly 

 hygroscopic substance to condense a little moisture to contend 

 with, but also its mother-liquor contained something in solution 

 which remained as a viscid, non-volatilising residue which 

 was probably pyrosulphite. Et Na S2O5. Instead, therefore, of 

 stopping the entrance of more sulphur dioxide into the Hask 

 when all ammonia had been neutralised, the operation was 

 continued for a much longer time until, as stated above, much 

 sulphur dioxide passed uncondeused. By this time, the crystals 

 had disappeared, being slowly dissolved up as the sulphur 

 dioxide increased in quantity. Whether this was a case of 

 mere solution in the sulphur dioxide, liquefied at so low a 

 temperature, or was due to the formation of pyrosulphite, cannot 

 with certainty be said. 



