ZINC. 109 



sequent ignition in n porcelain crucible. Erdmann's figures 

 give us tlie following percentages of metal in the oxide : 



80.247 

 80.257 

 80.263 

 80.274 



Mean, 80.260, zfc .0037 



Hence Zn = 64.9045, ± .019. 



If we combine the results of Jacquelain with those of Erd- 

 mann, we get a mean percentage of zinc, 80.324, dz .0032 ; 

 and an atomic weight of Zn = 65.168, ± .018. The reason 

 for the discordance l^etween the two experimenters will be 

 considered further along. 



Favre* em23loyed two methods of investigation. First, 

 zinc was dissolved in sulphuric acid, the hydrogen evolved 

 was burned, and the weight of water thus formed was de- 

 termined. To his weighings I append the ratio between 

 metallic zinc and 100 parts of water : 



25.389 grm. Zn gave 6.928 grm. H.^O. 366.469 

 30.369 " 8.297 " 366.024 



31.776 " 8.671 " 366.463 



Hence Zn = 65.803, ± .020. 



Mean, 366.319, d= 



The second method adopted Ijy Favre was to burn pure 

 izinc oxalate, and to weigh the oxide and carbonic acid thus 

 produced. From the ratio between these two sets of weights 

 the atomic weight of zinc is easily deducible. From Favre's 

 weighings, if CO 2 = 100, ZnO will be as given in the third 

 column below : 



7.796 grm. ZnO = 8.365 grm. CO.^. 93- 19^ 



7-342 " 7-883 " 93- '37 



5.2065 " 5.588 " 93.173 



Hence Zn = 65.8395, ± .022. 



Mean, 93.169, ± .012 



*Ann. Chim. Phys., (3,) 10, 163. 1844. 



