228 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



Corrected for the difference between Kegnault'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 : 



Zn = 



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: 



H = l. = 16. 



Van der Plaats 64.980, ± .0137 65.487 



Reynolds and Ramsay... 65.280, ± .0161 65.789 



Mallet 65.082, ± .0039 65.590 



Morse and Keiser 64.800, ± .0328 65.305 



Torrey 64.755, ± .0036 65.260 



General mean 65.079, ± .0036 65.587, ± .0036 



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

 zinc, returned espcntially 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, wliich 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 : 



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

 " Amer. Chem. Journ., 10, 311. 1S88. 



