RICHARDS AND ROGERS. — ATOMIC WEIGHT OF ZINC. 159 



1809. Gay Lussac, Mem. d'Arceiiil, II. 174 65.55 



1811. Berzelius, Pogg. Ann., VIII. 1«4 65.57 



1842. Jacquelaii), An. de Chim. et de Phys. [3.], VII. 204 , 6G.24 



1844. Favre, An. de Chim. et de Phys. [3.], X. 163 .. . 65.99 

 1844. Erdmann, Berz. Jahresber., XXIV. 132, and Pogg. Ann., 



LXII. 612 65.05 



1883. Pelouze and Fremy, Chem., p. 55 65.07 



1883, Baubigny, Comptes Rendus, XCVII. 906 .... 65.41 



1883. Marignac, Archiv. Sci. Phys. et Nat. [3.], X. 5, 193 . 65.30 



1885, Van der Plaats, Comptes Rendus, C. 55 ? 



1887. Reynolds and Ramsay, J. Ch. Soc. Trans., LI. 854 , 65.67 



1888. Morse and Burton, Am. Chem. Journ., X. 311 . . . 65.27 



1889. Gladstone and Hibbert, J. Ch. Soc. Trans., LV. 443 . 65.44 



The various results have been reached : — 



1. By converting a known weight of metallic zinc into the oxide 

 (Berzelius, Jacquelain, Erdmann, Morse and Burton). 



2. By the evolution of hydrogen from acids by metallic zinc, the 

 hydrogen being either measured or burned, (Jacquelain, Favre, Van 

 der Plaats, Reynolds and Ramsay). 



3. By the conversion of a salt of zinc into zincic oxide through 

 ignition (Favre, zincic oxalate ; Pelouze, zincic lactate ; Baubigny, 

 zincic sulphate). 



4. By the determination of the electrolytic equivalent of zinc 

 (Gladstone and Hibbert). 



5. By analysis of a haloid salt of zinc (Marignac.) 



The work of Morse and Burton by the first method is so far supe- 

 rior to the previous determinations made in the same way, that the 

 the older ones may be wholly neglected. The two or three possibil- 

 ities of infinitesimal error, such as the chance that the zinc might con- 

 tain impurities taken from the glass used for its distillation, may be 

 wholly neglected when compared with the great error due to the 

 occlusion of nitrogen and oxygen. As the amount of this error is 

 dependent upon the pliysical condition of the zincic oxide, it is im- 

 possible to make an acccurate correction except by the actual deter- 

 mination of the gas in the oxide remaining from the determinations. 

 From our own experiments * it would appear that a gram of zincic 



* These Proceedings, XXVIII. 200. 



