INÏEEACTION BETWEEN SULPHITES AND NITRITES. 299 



much larger quantity than in slow working, proportionately, that 

 is, to the fraction the solution had received of the quantity of 

 sulphur dioxide needed for complete sulphonation of the nitrite. 

 Thus, while, with quick working, acid carbonate separated in 

 abundance when 20 per cent, of all sulphur dioxide had been 

 absorbed, it only precipitated, and then much less copiously, 

 when 44 per cent, of all sulphur dioxide had been supplied 

 relatively more slowly to the solution. In another experiment 

 it showed itself only when 53 per cent, of the sulphur dioxide 

 had been added. The main condition, therefore, for early pre- 

 cipitation of acid carbonate is rapid addition of the sulphur 

 dioxide at first, — the same condition as favours growth of sul- 

 phonates at the expense of sulphite. 



Now for the discussion of the results. It becomes highly 

 probable from a consideration of these results, together with what 

 we know of the several substances concerned, that the first action 

 or tendency to act of sulphur dioxide when it enters the solu- 

 tion is to convert carbonate into normal sulphite and acid 

 carbonate, and to leave the nitrite untouched, and that this ac- 

 tion remains prominent so long as much normal carbonate 

 is undecomposed. Though this cannot be shown experimentally, 

 it is certain that this action does take place, for its products 

 present themselves freely, products which could not be derived 

 from the sulphonation of the nitrite. Both normal sulphite and 

 acid carbonate are active along with sulphur dioxide in sulphon- 

 ating nitrite. 



In accordance with what is stated in III. d. the normal 

 sulphite and acid carbonate together slowly disappear of them- 

 selves from the solution when addition of more sulphur dioxide 



