CARBON. 29 



J. J. Berzelius : earlier determinations. 



In 1817 Berzelius attempted to determine the atomic 

 weight of carbon by two analyses of plumbic carbonate. 

 [These analyses calculated for "Pb = 206.926 (Stas,) give C 

 = 11.998 and 11.984, or 74.99 and 74.90.] Considering the 

 diflerence too great, he calculated the atomic weight from 

 Biot and Arago's determination of the specific gravities of 

 carbon di-oxide and oxygen, 1.10359 and 1.51961. Berze- 

 lius gives 75.33 as the result; [I make it 75.394.] Subse- 

 quently, (1819,) Berzelius and Dulong determined these 

 specific gravities more accurately at 1.524 and 1.1026 whence 

 he calculated C = 76.487. This number was accepted until 

 Dumas showed it to be false, although in the mean time 

 carbon di-oxide had been shown to be a condensible gas. 

 According to Dumas, Berzelius at one time accepted a value 

 76.52 of which I have found no account. In Berzelius' 

 Lehrbuch, 3, 1174, 76.48 is a misprint for 76.437. {Berzelius' 

 Lehrbuch der Chemie, 5th ed., 3, 1197, et passim.) 



T. Thomson : 13 {O = 16) ; 75 (0 = 100). 



Thomson found the specific gravity of carbon di-oxide 

 1.52673. Assuming the specific gravity of oxygen at 1.1111, 

 chiefly to accord with the supposition that air is a compound 

 containing 20 per cent, of oxygen, he calculates the atomic 

 weight of carbon at 75. {Erdmann's Journ. fUr Prak. Chem., 

 8, 1836, 372 ; Records of General Science, by R. D. Thomson, 

 1836, 179.) 



J. Dumas : about 12.16 (0 = 16); 76 (O = 100). 



From analysis of well crystallized naphthaline, Dumas in- 

 fers that the atomic weight of carbon cannot be so high as 

 76.44, and must be nearly as above. {Poggend. AnnaL, 44^ 

 1838,110.) 



J. J. Berzelius: 12.23 (0 = 16 ); 76.458 (0 = 100). 



One experiment was made on the decomposition of plum- 

 bic carbonate by heat, which gave C = 76.405. [If Pb =: 

 206.926, the data give C = 12.185, or 76.157.] Another 

 experiment was made on the oxalate, which gave C = 76.511. 

 Berzelius regards these results as confirmatory of the value 

 76.438. The plumbic carbonate was prepared by precipi- 

 tating the nitrate with ammonium carbonate. The oxalate 

 was obtained by decomposing the acetate with oxalic acid. 

 {Liebig's AnnaL, 30, 1839, 241.) 



