OXIMIDOSULPIIO.N'ATES OU SÜLPH.VZOTATES. 21 



sulphonated, principnlly into oxiuiide })ut pnitiy into nitrile. To 

 prevent heating u]) the solutions are best mixed ice-cold, but the 

 mixture may then be exposed to the ordinary temperature and left 

 so for a day. This process though successful is of little practical 

 value because the very soluble sodium oximidosulphonate cannot be 

 separated from the sulphite and nitrilosulphonate which accompany it. 

 rhe actual success of the process in forming much oximidosulphonate 

 has been ascertained therefore only by analysis : the excess of sulphite 

 having been precipitated as barium salt, the solution has been hvdro- 

 lysed, and the hydroxylamine estimated. In this way evidence has 

 been got that there is formed about 83 per cent, of the oximidosul- 

 phonate equivalent to the nitrite. 



The solution of rhe sodium salt thus obtained can be used to get 

 the potassium salt by double decomposition, like that prepared after 

 Raschig's directions, than which it is markedlv more productive and 

 gives a purer product. Raschig used only half as much inetasulphite 

 as we use and therefore, by our finding, left <me-third of the nitrite 

 undecomposed in the solution. He also added the potassium chloride 

 just after mixing. the sodium salts, and did not, it would seem, pre- 

 serve the coldness of the solutions necessary in presence of potassium 

 salts. By his method, consequently, much more nitrile is got than by 

 ours, in which the solution of the sodium salts is only treated with the 

 potassium chloride after it h;is stood a day, so as nearly to complete 

 the reaction, and then been cooled again in ice, to prevent as much as 

 possible the formation of nitrile which otherwise goes <jn, especially in 

 the potassium salt. Following this method the oximide is obtained 

 with so little nitrile accompanying it ;is onlv to become visible during 

 recrystallisation of the product. But these points are now^ of no im- 

 portance as regards the preparation of the potassium salt, since there 

 are according to our experience, the Tnu<;h better direct processes for 



