ZINC. 151 



Corrected for the difference between Regnault's value for H and the 

 new value, this becomes Zn = 64.800, .0328. 



The second student series was published by Torrey,* who gives 15 

 determinations, as follows : 



65.36 64.96 



65.30 64.70 



64.92 65.00 



64.72 64.78 



65.04 64.44 



64.80 65.24 



65.20 64.92 

 64.90 

 Mean, 64.952, dr .0436 



Corrected as in the other series, this gives Zn 64.755, .0436. 

 The five corrected means for the ratio H : Zn may now be combined, 

 thus : 



Van der Plaats 64.980, .0137 



Reynolds and Ramsay 65.280, .0161 



Mallet 65.082, .0039 



Morse and Keiser 64.800, .0328 



Torrey 64.755, .0436 



General mean 65.079, .0036 



Morse and Burton, f in their determinations of the atomic weight of 

 zinc, returned essentially to the old method adopted by Erdmann and 

 by Jacquelain. Their zinc was obtained spectroscopically pure by dis- 

 tillation in a vacuum, and was oxidized by nitric acid which left abso- 

 lutely no residue upon evaporation. The conversion to oxide was 

 effected in a porcelain crucible, which was enclosed in a larger one, and 

 the ignition of the nitrate was carried out in a muffle. In weighing, the 

 crucible was tared by one of nearly equal weight. Results as follows : 



Wf. Zn. Wt. ZnO. Percent. Zn in ZnO. 



* Amer. Chem. Journ., 10, 74, 1888. 

 t Anier. Chem. Journ., 10, 311. 1888. 



