INTERACTION BETWEEN SULPHITES AND NITRITES. 309 



ting zinc sulphate witli barium nitrite and filtering. Zinc sul- 

 phite in solution in sulphurous acid was made from zinc oxide 

 in water and sulphur dioxide. The two solutions, suitably pro- 

 portioned and with ice floating in them were mixed. iSTo gas 

 came off, zinc sulphite precipitated, and the solution proved to" 

 contain zinc hydroximidosulphate present in it in large quantity. 

 Mercurous salts and silver salts. — Experiments, already re- 

 ferred to in sect. III. /. of this paper, sufficiently establish that 

 mercurous and silver nitrites are readily sulphonated. It is nOAV 

 evident that the sulphouation of nitrites is a general reaction, 

 essentially independent of the nature of the base, which only 

 effects the preservation of the products. It is not the salts which 

 are sulphonated but nitrous acid itself. 



V. — What Nitrous Acid becomes when Sulphonated. 



In the paper preceding this it has been established that 

 neither the abundant experimental work of other chemists and 

 ourselves nor theoretical considerations afford any support to the 

 view that the double sulphouation of nitrous acid into a hydrox- 

 imidosulphate occurs in two stages, or that a monosulphonated 

 nitrous acid, ON'SOgH or (HO)2N'S03lI, must be the first product 

 of its change. In the present communication it is shown that 

 the acidity necessary for the sulphouation of a nitrite points 

 clearly to the fact that it is in every case the acid itself, and 

 not its salts, which is directly sulphonated. We are, therefore, in 

 the position to affirm that the fundamental action in the form- 

 ation of all Fremy's sulphazotised salts is the interaction between 

 actual nitrous acid and a pyrosulphite, in which they unite al- 

 ways to form the one substance, the two-thirds normal hydrox- 



