54 THE ATOMIC WEIGHTS. 



From the acetate, CO^ = .40724, zh .000076 

 " oxalate, " = .40718, ± .oooi§5 



General mean, " = .40723, dr .000071 



Here the slight error due to the impurity of the oxalate 

 becomes of such trifling weight that it practically vanishes. 



From these data, if Ag = 107.675, ± .0096, CO, = 

 43.8485, ± .0086. 



Hence C = 11.9219, ± .0111. 



As has already been said, the volatility of silver renders 

 all the foregoing results more or less uncertain. Far better 

 figures are furnished by the combustion of carbon directly, 

 as carried out by Dumas and Stas* in 1840 and by Erdmann 

 and Marchandf in 1841. In both investigations weighed 

 quantities of diamond, of natural graphite, and of artificial 

 graphite were burned in oxygen, and the amount of dioxide 

 produced was estimated by the usual methods. The graphite 

 employed was purified with extreme care by treatment with 

 strong nitric acid and by fusion with caustic alkali. I have 

 reduced all the published weighings to a common standard, 

 so as to show in the third column the amount of oxygen 

 which combines with a unit weight (say one gramme) of 

 carbon. Taking Dumas and Stas' results first in order we 

 have from natural graphite : 



* Compt. Rend., 11,991-1008. Ann. Chim. Phys., (3,) i, i. 

 f Journ. f. Prakt. Chem., 23. 159. 



