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 : 



Zn = 



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, =b .0436 



Corrected as in the other series, this gives Zn =:^ 64.755, rb .0436. 

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

 thus : 



Van der Plaats 64.9S0, ± .0137 



Reynolds and Ramsay 65.280, zb .0161 



Mallet 65.082, ± .0039 



Morse and Keiser 64.800, =h .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. 



1.11616 1.38972 80.320 



1.03423 1.28782 80.308 



1.11628 1.38987 80.315 



1.05760 1.31681 80.316 



I. 04801 1.30492 So. 313 



1.02957 I. 28193 80.318 



1.09181 1.35944 80.315 



I. 16413 1-44955 80.305 



1.07814 1.34248 80.305 



1.12754 1.40400 80.306 



.91112 1.13446 80.310 



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

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



