228 DIVERS & HAGA : IDENTIFICATION AND CONSTITUTION OF 



until it became almost filled with silky needles very soluble in 

 water. So far it is easy to follow Freray with a full measure of 

 success if only the water used is limited to perhaps twice the 

 weight of the nitrite and that the heating effect of the nitrite is 

 counteracted by cooling. Claus and after him Raschig failed but 

 then inexplicably to us they did not start with Fremy's propor- 

 tions of nitrite to hydroxide, though even with the proportions 

 they took, success was possible with care. The salt thus formed 

 by Fremy was not tested and analysed by him until after it had 

 been changed (but without his having recognised the fact) by 

 the further treatment to which he submitted it. Before its 

 change it is potassium nitrito-2/ö normal hydroximidosulphate 

 described in the preceding paper, a neutral salt decomposed by 

 water into its constituent salts. Fremy's finished ' sulphazate ' 

 was strongly alkaline and very caustic and when decomposed by 

 water gave nitrite and the öjQ normal hydroximidosulphate — 

 not the 2/û-nornial salt. Also the analysis he gave of it fur- 

 nished numbers such as the original product could not have given 

 him. Instead of potassium, 33.10, sulphur, 18.06, and nitrogen, 

 7.9 per cent., he got potassium, 34.90, sulphur, 19. öö, and 

 nitrogen, 4.9. We can learn wliat his after-treatment was by 

 reference to other parts of his paper where he s])eaks of the care 

 necessary (when sulphonating the nitrite) to maintain the alka- 

 linity of the solution by adding potassium hydroxide from time to 

 time and of dissolving sulphazotised salts for examination in water 

 containing this alkali. Certain it is he must have added some 

 potassium hydroxide to the solution after getting it to crystallise, 

 as a precaution to preserve the salt. Now the effect of this ad- 

 dition is to change the composition of the product without much 

 aflecting its silky asbestus-like appearance. The change in com- 



