MOLECULAR VOLUME 

 If we tabulate the Chlor-Brom-Iodides we find 



687 



The volumes at o° show considerable changes, as judged by 

 the differences V — 2A.V., but these cannot be made out at 

 this point. Probably there is considerable heterogeneity in the 

 composition of the substances. 



At the M.P.'s the results are, however, surprisingly regular. 



Rodwell's Chlor-Brom-Iodides at the M.P. 



A (1) — (2) = AgBr + AgCl 6i*i — 3 x 20-36 = 6ri 

 A (4) — (2) = 3AgI i22'i — 6 x 20*36 = 121*1 



Thus Ag I = 2 x 20*36 Ag Br = 2 x 20*36 and AgCl = 1 x 20*36. 



These three Halogen Compounds of Silver in the above complex 

 compounds possess volumes which stand to each other in the 

 simple relationship of 



Ag I : AgBr : AgCl = 2:2:1. 

 This occurs at the M.P. We note that 



Vol. of Agl at 



o°d -5673 is 41*42 

 max. dens. 163 d '5771 is 40*72 = 2 x 20*36 

 mol. den. 527 d '5522 is 42*56 



This compound diminishes in volume from o° to 163 , and then 

 increases to the M.P. 



It is thus remarkable that, in combination at the M.P., the 

 volume of Agl is the same as its volume at the maximum 

 density when free. Not only is this the case, but Agl imposes 



