154 BY W. ROY ELLIOTT, B. SC. 



As the thin sheets used in my experiments may have con- 

 tained a different amount of hydrogen from that present in 

 commercial zinc, I have made some experiments on freshly 

 precipitated cathodes about 2.7 mm. thick from Trail, B. C, 

 obtained through the courtesy of Alessrs. Alurray and Willis. 

 Determinations were made on strips of the cathodes and on 

 portions carefully planed free from oxide. The results are a 

 little less than those obtained from the thinner strips. 



Apparent S. G. C. C. in a gram of zinc 



7.03 0.31 



7.08 0.38 



7.08 0.40 



0.54 



Strips of commercial electrolytic zinc were heated to various 

 temperatures for a short time, cooled, and the specific gravities 

 determined. The "warts" mentioned by Ralston appeared 

 on the inside surface at about 165° C, and there was marked 

 bending with the inside surface convex. 



Temperature yXpparent Specific Gravity 



A. B 



20° 6.93 6.99 



103° 6.90 6.93 



165° 6.96 6.93 



200° 6.86 6.89 



254° (^.11 6.78 



305° 6.50 6.58 



400= 6.05 5.98 



The effect of heating on the apparent specific gravity of the 

 zinc is quite marked. 



It appears then, that the hydrogen present in cathode zinc 

 is less than that found previously by Schwarz, and consequently 

 the pressures developed inside the zinc are small. 



