ZINC. 135 



found that 100 Zn = 24.41 oxygen. This value is repeatedly 

 cited in his memoir. {Gilbert's Ann., oO, 1811, 297; Me- 

 moire D'Arceuil, 2, 174.) Wollaston. gives the same figures 

 on Gay-Lussac's authority. {Phil. Trims., 104, 1814, 21.) 

 Wollaston calculates from these data Zn = 410, (O = 100.) 

 Berzelius in each of two experiments got 100 Zn = 124.4 

 oxide. {Gilbert's Ami., 37, 1811, 460.) In Poggend. Ann., 

 8, 1826, 184, as well as in his Lehrbuch, Berzelius cites 

 Gay-Lussac as having found 100 Zn = 24.8 oxygen. He 

 states that his own determinations were in perfect accor- 

 dance with these figures, and calculates from them the 

 atomic weight of zinc at 403.226 or 64-53, and this was the 

 accepted value for many years. I cannot find any other 

 determinations hy either of these chemists, and am obliged 

 to suppose that there was a mistake made in recording the 

 data from which Berzelius made his calculations ; if so, 

 it is remarkable that neither Berzelius nor the other 

 chemists who determined this value perceived it ; for the 

 question was reopened during Berzelius' life, and A. Erd- 

 mann made his determination at Berzelius' request. 



V. A. Jacquelin : 66.24, (O = 16) ; 414 (0 = 100). 



This number was reached by measuring the amount of 

 hydrogen developed by a known weight of zinc from sul- 

 phuric acid on the supposition that the specific gravity of 

 hydrogen is 0.0624. The results seem to have been incon- 

 sistent. Subsequently Jacquelain arrived at the same 

 number by oxidizing an impure zinc of known composi- 

 tion. {Paris Comptes Bend., I4, 1842, 636; and Annal. de 

 Chvm. €t de Phys., (3,) 7, 1843, 204.) 



P. A. Favre : 66, (O = 16 ) ; 412.5 (O = 100). 



Favre made four experiments on the combustion of zinc 

 oxalate, the carbon di-oxide being collected and its weight 

 compared with that of the oxide. The mean result was 

 Zn = 412.66 ; extreme difterence, 1.11. C = 75. He also 

 made three experiments by passing the hydrogen developed 

 by a known weight of zinc over cupric oxide, the water 

 being caught. These experiments gave in mean Zn = 

 412.16; extreme difiference, 0.65 for H = 12.5. {Annal. de 

 Chvm. et de Phys., (3), 10, 1844, 163.) 



A. Erdmann; 65.05 (0 = 16); 406.591 (O = 100). 

 Determined by oxidizing pure zinc with nitric acid, and 



