78 THE ATOMIC WEIGHTS. 



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

 joined : 



1. 5.1217 g rm - c g ave 18.7780 CO 2 . 2.6664 



2. 9.0532 " 33- I 93i " 2.6664 



3. 13.0285 " 47.7661 " 2.6663 



4. 11.7352 " 43.0210 " 2.6660 



5. 19.1335 " 7o.i33 6 " 2.6655 



6. 4.4017 16.1-352 " 2.6657 



Mean, 2.6660, =fc .0001 



This combines with the previous series thus : 



Dumas and Stas, first set 2.6683, .0005 



Dumas and Stas, second set 2.66985, .0013 



Dumas and Stas, third set 2.6665, .0007 



Erdmann and Marchand, first set 2.6636, .0007 



Erdmann and Marchand, second set 2.6637, .0009 



Roscoe 2.6654, d= .0006 



Friedel 2.6634, .0004 



Van der Plaats 2.6660, .0001 



General mean 2.6659, .0001 



Another very exact method for determining the atomic weight of car- 

 bon was employed by Stas* in 1849. Carefully purified carbon mo- 

 noxide was passed over a known weight of copper oxide at a red heat, 

 and both the residual metal and the carbon dioxide formed were weighed. 

 The weighings were reduced to a vacuum standard, and in each experi- 

 ment a quantity of copper oxide was taken representing from eight to 

 twenty-four grammes of oxygen. The method, as will at once be seen, 

 is in all essential features similar to that usually employed for determin- 

 ing the composition of water. The figures in the third column, deduced 

 from the weights given by Stas, represent the quantity of carbon mo- 

 noxide corresponding to one gramme of oxygen : 



9.265 grm. O = 25.483 CO 2 . .75046 



8.327 " 22.900 " .75010 



13.9438 " 38.35 1 " .75040 



11.6124 " 3L935 " .75oo8 



18.763 " 51.6055 " .75039 



19.581 " 53-8465 " -74994 



22.515 " 61.926 " .75043 



24.360 " 67.003 " -7553 



Mean, 1.75029, db .00005 



For the density of carbon monoxide the determinations made by 

 Leducf are available. The globe used contained 2.9440 grm. of air. 



*Bull. Acad. Bruxelles, 1849 (*), 31. 

 fCompt. Rend., 115, 1072. 1893. 



