Ionization in Air enclosed in a vessel of Ice. 431 



two being made from ordinary tap-water drawn from Lake 

 Ontario, and the other from water distilled in a large still in 

 the Chemical Laboratory of the University of Toronto. In 

 making these ice vessels a number of galvanized-iron trays 

 were made which were annular in form. The water was 

 poured into these, and the trays were placed out in the open 

 until the water was frozen solid. 



The ice was then taken out of these trays, carefully 

 scraped, and a cylinder was built up b}' placing these ice- 

 rings one upon the other and frozen together. The solidified 

 ice cylinder was then placed on a thick plate of ice and 

 frozen to it, and finally the top of the cylinder was closed 

 with a second plate of ice. Before the ice cylinders were 

 used, all chinks and cracks were carefully rilled with water 

 when the temperature was about 10° 0. below zero, so that 

 the ice cylinders prepared in this way were, when finished, 

 one piece of ice and were air-tight apart from any porosity 

 which the ice possessed. The appearance which the "Wolfe 

 electrometer and the cylinders of ice and zinc when mounted 

 on the Wilson electrometer presented is shown in figs. 3, 

 4, and 5 on the Plate accompanying this paper. It should 

 be mentioned that the measurements with the ice receivers 

 were made when the temperature ranged from 1° 0. below 

 zero to 10° C. below zero. 



III. Results and their discussion. 

 Numerous sets of readings were taken at the three stations 

 and a summary of the final results compiled from these is 



given m Table I. 



Table I. — Ionization of Air 

 Summary. 



Ions per c.c. Capacity 

 per Si'Cond. c.c. 



Zinj receiver in Library 7*76 



Wolff electrometer in Library 7-04 



Zinc receiver at House 7*11 



WolfF electrometer at House 7"66 



Zinc receiver on Bay 4(i5 



Wolff electrometer on Bay 4 - 3S 



Tap-water ice receiver at Utilise 4*37 



Tap-water ice receiver on Bay 2"60 



Distilled-water ice receiver on 13a y ... 5*5 



20.405 



2,000 



29,465 



2,000 



20,405 



2,000 



3.->.327 

 31,410 



28.67."» 



As the numbers show, the readings obtained for the con- 

 ductivity with the Wolff electrometer in the Library of the 



