272 



Mr, Exleys Application of 



corrected. From the calculated and experimental specific 

 gravities of 57 compounds in the table appended to the 8th 

 proposition, it appears to me, that the numbers, as given 

 by Dr. Thomson, are nearer the truth than those given by 

 Berzelius ; and this more particularly seems to be the case 

 in respect to two or three, which I have examined more at 

 large, as may be seen in respect to carbon from the ten 

 compounds in the following table. The specific gravities 

 are calculated by a rule drawn from the 8th proposition, 

 namely to multiply the sum of the atomic weights of the 

 elements by the specific gravity of hydrogen, when the 

 elements combine in single groups, and by half that sum 

 when they combine in double groups. 



In all these ten substances, if 12ibe taken for the atomic 

 weight of carbon, the calculated specific gravity exceeds that 

 found by experiment. In three of them it is so even when 

 12 is taken, and in the rest defect is very much less than 

 the excess, except in naphthaline, which shews that 12 is 

 much nearer the true atomic weight of carbon than \2\*\ 



* I have shewn from considerations connected with its specific heat, that the 

 atomic weight of carbon must be -75 or 12* and cannot be -764. — Records, vol. ii. 

 38.~Edit. 



