182 Mr. H. Croft's Abstract ofUv. H. Kopp's Researches 



In the chromates we may assume Cr C = 228. 

 In the wolframates WC = 244. 



We must assume.that there are two groups of chlorides, in 

 one of which the atomic volume of CF = 196, and in the 

 other 245. 



Neither of the above assumed numbers will explain the 

 specific gravity of bichloride of tin ; it seems, however, unne- 

 cessary to assume another value for the sake of only one sub- 

 stance. 



The density of several iodides may be approximately ex- 

 plained by assuming the atomic volume of iodine = 361. In 

 the potassium and silver-salts it is probably 463. 



The atomic volume of bromine in the salts of lead and silver 

 is = 233 ; in that of mercury = 290 ; and in that of potassium 

 = 375. These assumptions must be confirmed by more ob- 

 servations. Dr. Kopp then proceeds to a criticism of Schro- 

 der's work : he compares the results therein obtained with 

 those given above : he shows that Schroder has made a great 

 many assumptions to explain but few facts, and has not men- 

 tioned those salts which do not agree with his theoretical 

 formulae, and he therefore considers his own theory as the 

 simpler. 



The density of many oxides of the heavy metals may be 

 explained by assuming the atomic volume of oxygen to be 

 = 32. 



