(^XlMIDüSULPHOXATES Ol! SÜLPHAZOTATES. 29 



nitrite and sulphite. The precipitnterl oximidosiilplionnte can he 

 dissolved in hot water containing for safety a little ammonia, and from 

 the solntioM he got in sfood and characteristic crystals of uTeat ijuritv 

 and comparative stahility. The limit to the (|uantity of water to be 

 used is given hy the conditicjii that there must be enough not to lie 

 thickened by the separation of the insoluble oximidosul])honate. When 

 passing the sulphur dioxide into tlie flask closed with a cork holding- 

 inlet and outlet tubes and the thermometer, and with the inlet tube 

 endinii' seven or eio-lit centimeters above the surface of the solution, 

 and even when the alkali is used as carbonate so that carbon dioxide 

 is freely escaping, it is remarkable to observe the almost [M-rfect ab- 

 sorption of the sul])hui- dioxide by the well-agitated s<ilutioii. 



l^rrjxiratidii nf ((ll:nli)ii- n.riiniih)sii1ii]ioii(it<s from tlw 

 Ht'iitnil soils. 



Alkaline sodium o.i'iniiilo.suli)]ionates. — Tlie alkaline s<^dium oximido- 

 sulphonate, Na.NSoO;. corresponding to Raschig's haHic potassiuin 

 siilpliazotate, can be got by dissolving tlie neutral salt in water, adding 

 just the calculated quantity of sodium hydroxide, and evaporating to 

 the crystallising ])oint in a vacuum desiccator. The possibility of 

 ])reparing the salt in this way is of theoretical importance, but the salt, 

 iDeing less solid^le in presence of sodium hydroxide, can also be pre- 

 pared at once as a crystalline precipitate by adding the sodium hydrox- 

 ide in excetss to a «concentrated solution of neutral sodium oximido- 

 sulphonate. The ci-ystals are drained on a tile and recrystallised once 

 or more by dissolving and evaporating. 



A Hess alkaline sodium salt,, NasH(iSrS., (,)-):.,. is ol)tained when a 

 solution of the neutral oximidosulphonat«^ is evaporated with some- 

 what less sodium hvdroxide than is needed to form the above salt, 



