200 THE ATOMIC WEIGHTS. 



127.100 

 127.064 



^ Mean, 127. 082, =b .012 



Van der Plaats * prepared pure stannic oxide from East Indian tin 

 (Banca), and upon the material obtained made two series of experiments J 

 one by reduction and one by oxidation. The results, with vacuum 

 weights, are as follows, the ratio between Sn and Sn0 2 appearing in the 



third column : 



Oxidation Series. 



9.6756 grm. tin gave 12.2967 SnO 2 . 127.091 



12.7356 16.1885 " 127.114 



23.4211 " 29.7667 " 127.093 



Reduction Series. 



5-5 OI 5 g rm - Sn 2 S ave 4.3280 tin. 127. 1 14 



4.9760 3-9 T 45 " 127.117 



3.8225 " 3.0278 " 127.086 



2.9935 " 2.3553 " 127.096 



Mean of both series as one, 127.102, .0033 



The reductions were effected in a porcelain crucible. 



Bongartz and Classen f purified tin by electrolysis, and oxidized the 

 electrolytic metal by means of nitric acid. The oxide found was dried 

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

 several hours in a gas-muffle. Some reduction experiments gave values 

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

 ratio added by me in a third column : 



Sn. SnO^ Ratio. 



2.5673 3- 2 57o 126.865 



3.8414 4-8729 126.852 



7.3321 9. 2 994 126.831 



5.43 6 7 6.8962 126.845 



7.3321 9- 2 994 126.831 



9.8306 12.4785 126.935 



11.2424 14.2665 126.896 



5.5719 7.0685 126.860 



9.8252 12.4713 126.932 



4-3959 5-5795 126.925 



6.3400 8.0440 126.877 



Mean, 126.877, .0080 



- We now have six series of experiments showing the amount of SnO a 

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

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

 series : 



* Corapt. Rend., 100, 52. 1885. 



fBerichte Deutsch. Chem. Gesell., 21, 2900. 1888. 



