104 ABSOLUTE ATOMIC WEIGHT. 



It is true that Dumas made determinations with graphite 

 as well as with the diamond. 



But the atomic weight which he adopts is the one 

 determined by means of the diamond only. 



To prove this we need only tabulate the determinations 

 made by Dumas (and Stas) in 1840, in our usual form (for 

 four places only). 



We shall add all other combustions in the same form. 



Combustions of Different Sorts of Carbons. 



Dumas and Stas 



Diamond, 5 Det., 695 628; 67 Mean 2 low. 



Graphite, Nat'l, 5 Det., 710 670; 40 u 16 high. 



Graphite, Artif., 4 Det., 744 654; 90 " 32 high. 

 Erdmann and MarcJiand : 



Diamond, 5 Det., 673 596; 77 Mean 30 low. 



Graphite, Nat'l, 3 Det., 647 609; 38 " 29 low. 



Graphite, Artif., i Det., u 39 low. 

 Roscoc : 



Diamond, 5 Det., 675 649; 26 Mean 5 low. 



Carbonado i Det., " 55 low. 

 Van der Plaats : 



Graphite, 3 Det., 664 663; i Mean 3 low. 



Sugar Coal, 2 Det., 660 655; 5 " 10 low. 



Paper Coal, i Det., " 10 low. 



I deem it superfluous to add many words to this striking 

 tabulation of the record. 



The figures -giving a total range of the mean, nearly one 

 hundred utterly condemn any combination of all these 

 determinations when the object is the determination of the 

 atomic weight of true carbon. 



For the first condition in such a problem is to use the 

 purest material possible; that is the diamond, which by its 

 very physical and chemical properties can be handled and 

 cleaned, as Dumas already accentuated. 



Even graphite ii natural " can not take the place of the 

 diamond for this purpose as also plainly implied in words 

 by Dumas half a century ago. Compare p. 48, supra. 



