CARBON. 73 



In the racemate we have : 



59.290 

 59.292 

 59-287 

 59.283 

 59.284 



Mean, 59.2872, .0012 

 Or, corrected, 59.2769 



And from the malate : 



61.996 

 61.972 

 62.015 

 62.059 

 62.011 



Mean, 62.0106, zb .0096 

 Or, corrected, 62.0016 



Now, applying to these mean results the atomic weights already found 

 for oxygen and silver, we get the following values for carbon : 



From the acetate C = 1 1-959, .0021 



From the tartrate " 11.967, .0019 



From the racemate " = 11.973, =h .0017 



From the malate " = 11.972, .0098 



Now these results, although remarkably concordant, are by no means 

 unimpeachable. They involve two possible sources of constant error, 

 namely, impurity of material and the volatility of the silver. These 

 objections have both been raised by Stas, who found that the silver tar- 

 trate, prepared as Liebig and Redtenbacher prepared it, always carried 

 traces of the nitrate, and that he, by the ignition of that salt, could not 

 get results at all agreeing with theirs. In the case of the acetate a similar 

 impurity would lower the percentage of silver, and thus both sources of 

 error would reinforce each other and make the atomic weight of carbon 

 come out too high. With the three other salts the two sources of error 

 act in opposite directions, although the volatility of the silver is probably 

 far greater in its influence than the impurity. Even if we had no other 

 data relating to the atomic weight of carbon, it would be clear from these 

 facts that the results obtained by Liebig and Redtenbacher must be 

 decidedly in excess of the true figure. 



Strecker, * however, discussed the data given by Liebig and Redten- 

 bacher by the method of least squares, using the Berzeliaii scale, and 

 assuming H = 12.51. Thus treated, they gave C = 75.415, and Ag = 

 1348.79 ; or, with =16, C = 12.066 and Ag = 107.903. These values 



*Ann. Chem. Pharm., 59, 280. 1846. 



