3*0 Dr. T. Carnelley on the 



one atom of C more, have the same molecular volume ; or, the 

 volume of one atom of C is equal to that of two atoms of H 

 thus : — 



Molecular Molecular 



weight. volume. 



/C 8 H 18 114 187 



\ C 10 H M 134 187 



f C 4 H 10 74 106-8 \ 



|C 6 H G 94 106-8 J 



Now it lias already been shown that the volume of CH 2 = 22; 

 therefore the specific volume of C = ll, and that of H = 5*5. 



In liquids belonging to different types, the volume of the 

 oxygen varies according to the manner in which it is com- 

 bined in the compound. When the is joined on to C by 

 one combining power only, its specific volume =7*8; but 

 when attached to C by both its combining powers, its specific 

 volume =12*2. A similar thing occurs in the case of S: its 

 specific volume in the former case being 23, and in the latter 

 28'6. The specific volume of Cl = 22*8, of Br =27-8, of 

 1 = 37*5. N in ammoniacal compounds =2*3, in cyanides 

 = 17*0, and in nitro-compounds =17*4. By the use of these 

 constants we may calculate the molecular volume of a com- 

 pound when its molecular formula is known, thus : — 



Calculated. Found. 



H 2 =2x5-5 + 7-8 = 18-8 18-8 



C 2 H 5 . OH =2x11 + 6x5-5 + 7-8 = 62-8 62-5 



CO. (CH 3 ) 2 = 3x 11 + 6x5-5 + 12-2= 78-2 77-6 



C 6 H 5 .NH 2 = 6x 11 + 7x5-5+ 2-3 = 106*8 106-8_ 



It appears then that the molecular volume depends not 

 only on the chemical composition, but also on the constitution 

 or arrangement of the atoms in the molecules. 



As regards the molecular volume of solids, Kopp (Pogg. 

 Ann. xlvii. p. 133; Hi. pp. 243, 262), and more especially 

 Schroeder (ibid. 1. p. 552, lii. pp. 269, 282, cvi. p. 226, 

 cvii. p. 113), have endeavoured to show that the hypothesis 

 that all bodies combine in whole volumes holds good not only 

 for gases and liquids, but also in the case of solids ; and 

 Schroeder has pointed out that " equivalent quantities of different 

 elements in uniting with the same quantity of a given element 

 (or compound radical) receive equal increments of volume." The 

 explanation of this appears to be that certain elements enter 

 into combination with the same volume which they occupy in 

 the free state. More recently Schroeder (Deut. chem. Ges. 



* Schorlemmer's ' Chemistry of the Carbon Compounds.' 



