LECTURE VIII.] HISTORY OF CHEMISTRY. 13! 



was introduced into the science by Davy, 1 constitutes the basis 

 of this hypothesis. Ampere 2 and Berzelius 3 were afterwards 

 chiefly instrumental in procuring its recognition. The superiority 

 of this view, with its purely dualistic basis, as compared with 

 the other, is indisputable ; for the compounds of ammonia 

 (ammonium compounds) now appear as analogues of the ordi- 

 nary salts, as their behaviour necessarily requires that they 

 should. The analogy was illustrated thus : 4 



Sal ammoniac - - (N 2 H 8 )CL ! KC1 2 Muriate of Potash 



Sulphate of Ammonia (N 3 1I 8 )OSO 3 KOSO 3 - Sulphate 



Nitrate ,, (N 2 H 8 )ON 2 O 5 ! KON. 2 O 5 Nitrate 



Acetate (NgHaJOQHgO^ KOC 4 H 6 O 3 - Acetate 



It is clear that this way of regarding substances could also 

 be applied to the compound ethers, if the radical C 4 H 10 were 

 assumed instead of C 4 H 8 . Berzelius took this step in i833. 5 

 He was led to do so not only by his predilection for the 

 ammonium theory, but also on account of newly discovered 

 facts which I shall state here. 



During the same year, Magnus, by acting with sulphuric 

 anhydride on alcohol and ether, had discovered ethionic and 

 isethionic acids. 6 The latter acid was obtained by the decom- 

 position of the former by means of water, and, according to the 

 analyses, it was isomeric with it. Its barium salt, in accord- 

 ance with the prevailing etherin theory, had the formula 

 QH 8 + 2SO 3 + BaO -f H 2 O assigned to it ; or, according to Mag- 

 nus, it was to be regarded as a compound of ether and anhydrous 

 sulphuric acid, with baryta. Liebig and Wohler's analyses 

 of barium sulphovinate, 7 which were confirmed by Magnus, 8 

 had fixed its composition as C 4 H 8 + 2SO ;J + BaO + 2H 2 O ; 



1 See p. 76. 2 Ann. Chim. [2] 2, 16, Note. 3 Gilb. Ann. 46, 131 ; 

 Berzelius, Lehrbuch. Third Edition. 4 Berzelius adopts NH 4 as an atom 

 of ammonium ; and yet this does not occur in combination any more than 

 an atom of ammonia NH 3 . Instead of it the double atom NH 4 ( = N 2 H 8 ) 

 always occurs. The isomorphism of ammonium chloride and potassium 

 chloride must have influenced him to write N-H 4 .C1 2 and not (NH 4 ) 2 C1 2 . 

 5 Pogg. Ann. 28, 626. 6 Annalen. 6, 152. 7 Ibid, i, 37. b Magnus, 

 loc. cit. 



