54 



SMITHSONIAN" MISCELLANEOUS COLLECTIONS 



VOL. 54 



burned carbonado. The combustions were effected in a platinum boat, 

 contained in a tube of glazed Berlin porcelain; and in each case the ash 

 was weighed and its weight deducted from that of the diamond. The 

 results were as follows,- with the ratios stated as in the preceding series : 



.0006 



Friedel's work,' also upon Cape diamond, was in all essential par- 

 ticulars like Eoscoe's. The data, after deduction of ash, were as follows : 



.4698 grm. C gave 1.7208 COj. 

 .8616 " 3.1577 " 



2.6628 

 2.6649 



Mean, 2.6638, ± .0004 



By Van der Plaats * we have six experiments, numbers one to three 

 on graphite, numbers four and five on sugar charcoal, and number six 

 on charcoal made from purified filter paper. Each variety of carbon 

 was submitted to elaborate processes of purification, and all weights were 

 reduced to a vacuum standard. The data, with ash deducted, are sub- 

 joined : 



Mean, 2.6660, ± .0001 



This combines with the previous series thus : 



Ratio. Atomic weight C. 



Dumas and Stas, first set 2.6683, ± .0005 11.9926 



Dumas and Stas, second set 2.6671, ± .0014 11.9981 



Dumas and Stas, third set 2.6662, ± .0009 12.0031 



Erdmann and Marchand, first set. . . 2.6636, ± .0007 12.0138 



Erdmann and Marchand, second set. 2.6637, dr .0009 12.0134 



Roscoe 2.6654, ± .0006 12.0057 



Friedel 2.6638, ± .0007 12.0129 



Van der Plaats 2.6660, ± .0001 12.0030 



General mean 2.6660, ± .0001 12.0030, ± .0005 



> Bull. Soc. Chim., 41, 100. 1884. 

 'Compt. Rend., 100, 52. 1885. 



