108 THE ATOMIC WEIGHTS. 



ZINC. 



The several determinations of the atomic weight of zinc 

 are by no means closely concordant. The results obtained 

 by Gay-Lussac* and Berzelinsf were undoubtedly too low, 

 and may be disregarded here. We need consider only the 

 work done by Jacquelain, Favre, and Axel Erdmann. 



In 1842 Jacquelain published the results of his investiga- 

 tions upon this important constant.^ In two experiments a 

 weighed quantity of zinc was converted into nitrate, and 

 that by ignition in a platinum crucible was reduced to oxide. 

 In two other experiments sulphuric acid took the place of 

 nitric. As the zinc contained small quantities of lead and 

 iron, these were estimated, and the necessar}^ corrections ap- 

 plied. From the weights of metal and oxide given by 

 Jacquelain the percentages have been calculated : 



Nitric Series. 



9.917 grm. Zn gave 12.3138 grm. ZnO. 80.536 per cent. Zn. 



9.809 " 12.1800 " S0.534 " 



Stdphuric Series. 



2.398 " 2.978 grm. ZnO. 80.524 " 



3.197 " 3.968 " 80.570 



Mean of all four, 80.541, ir: .007 



Hence Zn = 66.072, ± .028. 



The method adopted by Axel Erdmann || is essentially the 

 same as that of Jacquelain, but varies from the latter in cer- 

 tain important details. First, pure zinc oxide M^as prepared, 

 ignited in a covered crucible with sugar, and then, to com- 

 plete the reduction, ignited in a porcelain tube in a current 

 of hydrogen. The pure zinc thus obtained was converted 

 into oxide by means of treatment with nitric acid and sub- 



■* M6moire d'Arceuil, 2, 174. 



f Gilb. Annal., 37, 460. 



:j; Compt. Rend., 14, 636. 



II Poggend. Annal., 62, 611. Berz. Lehrb., 3. 1219. 



