AMIDOSULPHONIC ACID. 247 



real amidosulphonic acid used, apart from any water that might have 

 been absorbed by it before it was weighed. An important factor in 

 determining the constitution of the product is its original acidity ; its 

 acidity after hydrolysis of the imidosulphonate to amidosulphonate is 

 unimportant, being the same as that of the amidosulphonic acid taken. 

 The acidity before hydrolysis was ascertained by dissolving the mass in 

 a suitable manner, as follows, in volumetric potassium hydroxide and 

 titrating. As nearly as convenient, a cgm. mol. of the acid was taken 

 and fused, so that 10 cc. normal potassium hydroxide might be the 

 quantity of alkali to be measured. This quantity of alkali, placed in a 

 20 cc. stoppered bottle, was cooled in ice. The tube was broken on a 

 plate of glass by tapping it with a mallet, so as to expose much of the 

 fused Jump, and then this, along with all fragments of the tube which 

 had been in contact with it or near it, was most expeditiously dropped 

 into the potassium hydroxide. The stopper being firmly inserted, the 

 bottle with its ice-packing, was, without a moment's delay, shaken and 

 kept violently agitated until dissolution of the mass was complete. 

 With its stopper loosened, the bottle was placed in a beaker containing 

 water and 5 cc. normal hydrochloric acid, then opened, and its acidified 

 contents titrated, with methyl orange as indicator. 



In calculating the results, the amount of either sulphuric acid or 

 ammonia is enough to know, that of the other serving only as a check 

 of the accuracy of its determination, for the two amounts could not 

 but be equivalent. If all the acid were changed by heat, but only into 

 the one-third normal ammonium imidosulphonate, NH 4 N(S0 3 H) 2 , the 

 hydrolysis of this, exactly into imidosulphonate and sulphate, would 

 give half the sulphur and the nitrogen of the amidosulphonic acid as 

 sulphuric acid and ammonia (so it would, if all the acid were changed 

 half into amidosulphonic anhydride, half into ammonium pyrosul- 

 phate). If all the acid were changed into ammonium pyroimidosul- 



