82 ABSORPTlON OF NITRIC OXIDE IN UAS ANALYSIS. XI.-Absorption of Nit& Oxide in Gas Analpis. By EDWARD DIVERS. IT is well known that the vapour tension of nitric oxide, dissolved in the solution of a ferrous salt, interferes with the use of this reagent to remove nitric oxide from other gases. There is, however, another absorbent for nitric oxide which leaves nothing to be desired, whose use and value have remained unknown. This is a strong solution of either sodium or potassium sulphite to which a little alkali hydroxide has been added. It quickly absorbs every trace of nitric oxide, which it fixes in the form of hyponitrososulphate, Na,N,02S0,. I haveINTERACTION OF NITRIC OXIDE WlTE SILVER NITRATE. 83 already made satisfactory use of it to analyse the mixture of nitric oxide and nitrogen which is left on heating silver hyponitrite and allowing the solid and gaseous products to cool in contact with each other. The sulphite need not be very pure, the presence of sulphate or carbonate being of no importance. If carbon dioxide or other acid gasis present along with the nitric oxide, it is removed by alkali before using the sulphite mixture.