292 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



over a water-bath, then heated over a weak flame, and finally ignited for 

 several honrs in a gas-mnffle. Some reduction ex])eriments gave values 

 which were too low. The oxidation series was as follows, with the usual 

 ratio stated in a third column : 



Mean, 126.877, ± .0080 



Hence Sn = 119.06. 



We now have six series of experiments showing the amount of SnO^ 

 formed from 100 parts of tin. To Berzelius' single determination may be 

 assigned the weight of one experiment in Mulder and Vlaanderen'p 



series : 



Berzelius 127.200, ± .041 



Mulder and Vlaanderen 127.517, ± .029 



Dumas 127.105, ± .024 



Vlaanderen 127.082, ± .012 



Van der Plaats 127.102, ± .0033 



Bongartz and Classen 126.877, ± .0080 



General mean 127.076, ± .0026 



Dumas, in the paper previously quoted, also gives the results of some 

 experiments with stannic chloride, SnCl^. This was titrated with a solu- 

 tion containing a known weight of silver. From the weighings given, 

 100 parts of silver correspond to the quantities of SnCl^ named in the 

 third column : 



1.839 grm. SnCl« = 3.054 grm. Ag. 60.216 



2.665 " 4.427 " 60.199 



Mean, 60.207, ± .006 



Hence Sn = lir.97. 



Tin tetrabromide and the stannichlorides of potassium and ammonium 

 were all studied by Bongartz and Classen; who, in eacli compound, care- 

 fully purified, determined the tin electrolytically. The data given are 

 as follows, the percentage columns being added by myself : 



