212 HISTORY OF CHEMISTRY. [LECTURE XI. 



artificial bases, received important support from Hofmann's 

 method of preparing them. 48 Hofmann succeeded, by treating 

 the alkyl iodides with ammonia, in introducing the radicals 

 into the latter, and his experiments possess all the greater 

 importance from the fact that he also showed how to prepare 

 secondary and tertiary compounds, as well as substances cor- 

 responding to ammonium chloride and ammonium hydroxide. 



Thus : ^TT 4. IP TT Tsl^2^5 ITT 



IN -n- 3 T iv^o-Tj-5 -LN TJ j m 



H -2^5 



N7?B +ICH 3 =NC H 3 ,HI 

 v^rj-p, TJ- 



H 

 C 9 

 C"H 3 



N C 9 H, + IC 5 H n = NC H 3 , HI 



QH 5 (C 2 H 5 ) 2 



Nf TT , Jf~< TT XTT' "PT 



^ -LJ-Q T iv^qrir = IN V_x -tlo 



\^2"5/2 (t~* TJ \ 



N C H 3 I + AgHO = Agl + N^2' 2 0. 

 C H ^ W 3 



^5*^11 f TJ 



Mi* 1 !! 



I shall not leave the fact unmentioned that Paul Thenard 

 had discovered the organic phosphorus compounds in i845, 49 

 but that these only received their correct explanation now. 50 



Of other investigations, carried out at the beginning of the 

 fifties, which contributed to the establishment of the new theory 

 of types, I mention the discovery of the acichlorides by 

 Cahours ; 51 that of the anhydrides of monobasic acids by 

 Gerhardt ; Williamson's researches on dibasic acids ; and, 

 finally, the preparation of the acid amides of Gerhardt and 

 Chiozza. 52 



48 Annalen. 66, 129; 67, 61, 129; 70, 129; 73, 180; 74, I, 33, 117; 

 75. 35 6 ; 78, 253; 79, ii. 49 Comptes Rendus. 21, 144; 25, 892. 

 50 Compare Frankland, Annalen. 71, 215. 51 Ibid. 70, 39. Liebig and 

 Wohler had prepared benzoyl chloride and benzoyl-amide twenty years 

 before ; see Annalen. 3, 249. 52 Comptes Rendus. 37, 86. 



