56 THE ATOMIC WEIGHTS. 



of copper oxide at a red heat, and both the residual metal 

 and the carbon dioxide formed were weighed. The weigh- 

 ings were reduced to a vacuum standard, and in each ex- 

 periment 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 determining the composition of 

 water. The figures in the third column, deduced from the 

 weights given by Stas, represent the quantity of carbon 

 monoxide corresponding to one gramme of oxygen : 



9.265 grm. O = 25.483 CO,. 1.75046 



8.327 " 22.900 •' 1. 75010 



13-9438 " 38.351 " 1-75040 



II. 6124 " 31-935 " 1.75008 



18.763 " 51-6055 " 1.75039 



19.581 " 53-8465 " 1-74994 



22.515 " 61.926 " 1.75043 



24.360 " 67.003 " 1.75053 



Mean, 1.7 5029, =h .00005 



Hence the molecular weight of carbon monoxide is 

 27.9404, d= .0062. And C = 11.9771, ±: .0071. 



Now, in order to complete our discussion, we must com- 

 bine the four values we have found for carbon : 



1. By Liebig and Recltenbacher_.C = 12.0363, dz .0028 



2. By Maumene's figures " = 11. 9219, dz .01 11 



3. By combustion of carbon " = 11.9730, rfc .0030 



4. By Stas' method " =: I1.9771, i .0071 



General mean " = 12.0021, dr .0019 



But values one and two are hardly reliable enough to be 

 included in our final estimate. They involve dangerous 

 constant errors, and ought, therefore, to be disregarded. 

 Rejecting them altogether, and taking a general mean from 

 values three and four, we get for the most probable figure 

 for the atomic weight of carbon, C = 11.9736, ± .0028. If 

 oxygen is 16, then carbon becomes 12.0011. In other words, 

 the ratio between oxygen and carbon is almost exactly 16 

 to 12. 



