666 



Prof. J. Patterson on the Electrical 



1 min., in which case the result would be in agreement 

 with the others. It was impossible to make another film 

 without making a complete set. The average rate of deposi- 

 tion of the four films whose thickness was measured directly 

 is 0*612 X 10~ 6 cm. per min. The thickness of all the other 



by the 



cm. 



films was obtained by multiplying 0*612 X 10" 

 time of deposit. 



In fig. 10 time multiplied by resistance per cm. square is 

 plotted against the time of deposit, and in fig. 11 the specific 



Fiff. 10. 



200 



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DEPOSIT 





12 3*567 



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resistance for a given thickness against that thickness. 

 These results confirm those previously obtained ; that the 

 specific resistance remains constant down to a thickness of 

 less than 10 -6 cm., and that the specific resistance becomes 

 abnormal between 7*7 and 4*6 x 10~ 7 cm. Below this thick- 

 ness the increase of resistance with decrease in thickness is 

 very rapid. 



The effect of heating the films by an electric current was 

 also tried. The current from an 8-volt cell was passed 

 through a film 4*38 X 10~ 6 cm. thick, and having an initial 

 resistance of 26*72 ohms per cm. square. After heating the 



