198 EDWARD DIVERS AND MASATAKA OGAWA : 



But, within the last few years, a new class of alkyl metallo- 

 sulphites has come to be known and in this class the new ethyl 

 ammoniumsulphite must be placed. The first member to be 

 discovered was phenyl sodiumsulphite (Schall, Ber., 1892, 25, 

 1875 ; J. pr. Ch., 1893, [2] 48, 241), formed from sodium 

 phenoxide and sulphur dioxide ; next, came methyl magnesium- 

 sulphite, obtained by Szarvasy {Ber., 1897, 30, 1836) from 

 magnesium methoxide and sulj^hur dioxide, and, lastly, methyl 

 and ethyl sodiumsulphite and ethyl potassiumsulphite, prepared 

 from sodium or potassium ethoxide or methoxide, as the case 

 required, and sulphur dioxide (Rosenheim and Liebknecht, 

 1898, he. cit.). 



Schall has established that his salt is Na ' SO2 * OCeHg, 

 and Rosenheim and Liebknecht have given good reasons for 

 regarding their salts, and also Szarvasy's salt, as similarly 

 constituted — Na-SOo-OC^Hg; Mg (SO2 -00113)2, that is, as 

 having a constitution complementary to that of sulphonates. 

 Szarvasy, indeed, takes his sulphite to have a constitution 

 analogous to that of the ethyl magnesium carbonate, which he 

 has obtained in a similar way, but, in doing so, he ignores, 

 what seems so well established, that sulphites behave as the 

 analogues of formic acid and other carboxylic salts, rather than 

 of carbonates, though producible in the same way as the latter 

 salts. 



Quite special precautions have to 'be taken to ensure the 

 absence of water. Muspratt, passing '' dried " sulphur dioxide 

 and ammonia into ether, was surj)rised to get ammonium pyro- 

 sulphite : Carius found that " carefully dried " sulphur dioxide 

 formed only sodium sulphite when led into sodium ethoxide 

 dissolved in ^^ absolute ^^ alcohol (the italics are his), although, 



