126 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5-i 



And from the malate: 



61.99G 

 61.972 

 62.015 

 62.059 

 62.011 



Mean, 62.0106, ± .0096 

 Or, corrected, 62.0016 



These results are by no means unimpeachable. They involve two pos- 

 sible sources of constant error, namely, impurity of material and tlie 

 volatility of the silver. These objections have both been raised by Stas, 

 who found that the silver tartrate, prepared as Eedtenbacher and Liebig 

 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 apparently 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 Eedtenbacher and Liebig must be decidedly in excess of the 

 true figure. 



Strecker,' however, discussed the data given by Eedtenbacher and Lie- 

 big by the method of least squares, using the Berzelian scale, and as- 

 suming 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 of course 

 would change somewhat upon adoption of the modern ratio between 

 and H. 



Observations upon silver acetate, like those of Eedtenbacher and Liebig, 

 were also made by Marignac' The salt was prepared by dissolving 

 silver carbonate in acetic acid, and repeatedly recrystallizing. Two ex- 

 periments gave as follows : 



3.3359 grm. acetate gave 2.1561 Ag. 64.633 per cent. 



3.0527 " 1.9727 " 64.621 



Mean, 64.627, ± .0040 

 Eeduced to a vacuum, this becomes 64.609. 



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



2 Ann. Chem. Pharm., 59, 287. 1S46. Otuvres Completes, 1, 184. 



