TIN. 205 



Berzelius * oxidized 100 parts of tin by nitric acid, and 

 found that 127.2 parts of SnO^ were formed. 



The work done by Mulder and Vlaanderenf was done in 

 connection with a long investigation into the composition of 

 Banca tin, which was found to be almost absolutely pure. 

 For the atomic weight determinations, however, realh- pure 

 tin was taken, prepared from pure tin oxide. This metal 

 was oxidized by nitric acid, with the following results. 100 

 parts of tin gave of SnO, : 



127.56— Mulder. 

 127.56 — Vlaanderen. 

 127.43— 



Mean, 127.517, ±2 .029 



Dumas t oxidized pure tin by nitric acid in a flask of 

 glass. The resulting SnO, was strongly ignited, first in the 

 flask, and afterwards in platinum. His weighings, reduced 

 to the foregoing standard, give for dioxide from 100 parts 

 of tin the amounts stated in the third column : 



12.443 g""™- ^" g^^'s 15.820 grm. Sn02. 127.14 



15.976 " 20.301 " 127.07 



Mean, 127.105, zb .024 



In an investigation later than that previously cited, 

 Vlaanderen li found that when tin was oxidized in glass or 

 porcelain vessels, and the resulting oxide ignited in them, 

 traces of nitric acid were retained. When, on the other 

 hand, the oxide was strongly heated in platinum, the latter 

 was perceptibly attacked, so much so as to render the results 

 uncertain. He therefore, in order to fix the atomic weight 

 of tin, reduced the oxide by heating it in a porcelain boat 

 in a stream of hydrogen. Two experiments gave Sn = 

 118.08, and Sn =- 118.24. These, when O = 16, become, if 

 reduced to the above common standard, 



* Poggend. Annal., 8, 177. 



f Journ. fur Prakt. Chem., 49, 35. 1849. 



J Ann. Chem. Pharm., 113, 26. 



II Jahresbericht, 1858, 183. 



