CONSTITUTION OF NITKOSOSULPHATES. \()J 



to afford us sufficient potassium ethyl sulphate in a pure state, for 

 thorough identification. In one experiment we prepared a solution 

 containing 46*25 grams of potassium nitrososulphate in 1450 grams 

 of 22*8 per cent, spirit, and in the other, 14*45 grams of the salt in 

 212 grams of 14 per cent, spirit. Both solutions were almost 

 saturated; we had intended the one to be spirit of 25°/ alcohol and the 

 other of 15°/ alcohol. 



The solutions were left for 16 days, at the summer temperature 

 in loosely stoppered bottles, though a few days less might have sufficed 

 for the decomposition of the salt to be complete. Potassium sulphate 

 gradually crystallised out and nitrous oxide slowly escaped. In our 

 first paper on the subject in this volume, we stated (p. 92) that the evolu- 

 tion of nitrous oxide from the aqueous solution was actually arrested by 

 adding alcohol; but that was a mistake. It goes on undiminished, 

 but, being spread over a much longer time, becomes much less 

 perceptible. We also observed a slight but unmistakable odour of 

 aldehyde during the decomposition, and were just able to reduce silver 

 by it in the solution (the alcohol used being quite free from this 

 impurity). Its formation may perhaps be accounted for by supposing 

 a minute quantity of the nitrososulphate to have decomposed into 

 nitric oxide and sulphite, the former then acting as carrier of atmos- 

 pheric oxygen to the alcohol. 



The volume of the solution of the 46'25 grams of salt being so 

 large, it was reduced to half by evaporating the solution at 70-75° in 

 shallow, flat-bottomed glass pans. The alkali present was then 

 neutralised with volumetric sulphuric acid, the solution made again 

 slightly alkaline, and the evaporation continued and completed in a 

 vacuum over sulphuric acid, occasionally interrupting the process to 

 remove the potassium sulphate that had separated, in order that the 

 quantity of it in the dried-up residue should not be very large in 



