300 HISTORY OF CHEMISTRY. [LECTURE XV. 



H , Oo, N corresponding to (CH 3 ).,, (C.,H 5 )., 

 Hg,Zn" , C 2 H;, C 3 H 6 " 



K.,O, 

 CaO, ZnO 

 Bi. 2 3 , Sb. 2 0j 

 SnO , SiOo 



KOH 

 Ca(OH)o 

 Bi(OH)" 3 

 Sn(OH) 4 



(CH 3 )oO, (CoH 6 ),0 

 C 2 H 4 O, C,H 6 O 



(C 3 H 5 ) 2 3 



COo 



CH 3 OH, C,H 6 OH 

 CoH 4 (OH) 2 , C 3 H,(OH)o 

 C 3 H 5 (OH) 3 

 C 4 H 6 (OH) 4 



Of decisive importance, however, as regards the nature of 

 the molecule of mercury, are the experiments of Kundt and 

 Warburg, 8 which may be adopted as a direct proof of Canniz- 

 zaro's view. These physicists, by observing the velocity of sound 

 in mercury vapour, determined the ratio of the specific heats at 

 constant pressure and at constant volume to be 1.67 a number 

 furnished by the mechanical theory of heat, on the assumption 

 that the total energy of the gas consists of the translatory motion 

 of the molecules. The demonstration, furnished by Victor 

 Meyer, of the variable vapour density of iodine, 9 which, as 

 Crafts in particular has shown, 10 eventually sinks to one-half 

 of the original density and then remains constant, can only 

 point to the fact that. the molecule of iodine, at high tem- 

 peratures, consists of a single atom. 



A great deal more trouble was experienced in fixing the 

 molecular weights of compounds, in those cases where the 

 numbers calculated from the vapour densities did not agree 

 with those deduced from the chemical relationships of the sub- 

 stances. In his determinations of the relative densities of 

 vapours, Bineau obtained such remarkable numbers that he 

 considered decomposition to be the cause of the peculiar 

 volume relations. 11 Thus he found the density of ammonium 

 carbamate (anhydrous carbonate of ammonia, as he calls it) to 

 correspond to six volumes, whence he assumes a decomposition 

 into four volumes of ammonia and two of carbonic anhydride. 



8 Berichte. 8, 945. Pogg. Ann. 157, 353. 9 Berichte. 13, 394. 

 10 Comptes Rendus. 92, 39. n Ann. Chim. [2] 68, 434 ; 70, 272. 



