ATOMIC WEIGHTS 53 



1.000 grm. C gave 3.G71 grm. CO.. 2.6710 



.0005 



.0014 



Mean, 2.6662, ± .0009 



Erdmann and Marchand's figures for natural graphite give the follow- 

 ing results : 



1.5376 grm. gave 5.6367 grm. CO.. 2.6659 



1.6494 " 6.0384 " 2.6609 



1.4505 " 5.31575 " 2.6647 



In one experiment 1.8935 grm. of artificial graphite gave 6.9355 grm. 

 COo. Eatio for 0, 2.6628. This, combined with the foregoing series, 

 gives a mean of 2.6636, ±.0007. 



With the diamond tliey found : 



.8052 grm. gave 2.9467 grm. COo. 2.6596 



1.0858 " 3.9875 " 2.6632 



1.3557 " 4.9659 " 2.6629 



1.6305 " 5.97945 " 2.6673 



.7500 " 2.7490 " 2.6653 



Mean, 2.6637, ± .0009 



In more recent years the ratio under consideration has been carefully 

 redetermined by Eoscoe, by Friedel, and by Van der Plaats. Eoscoe ' 

 made use of transparent Cape diamonds, and in a sixth experiment he 



1 Ann. Chim. Phys. (5), 26, 136. Zeit. anal. Chem., 22, 306. 1SS3. Compt. Rend., 94, 1180. 1SS2, 



