652 Prof. J. Patterson on the Electrical, 



two metals. These positions of maxima and minima were 

 almost independent of the tension and of the length of the 

 spring. 



Whether these complicated phenomena are capable of being 

 explained simply by the elastic vibration and the magnetic 

 change in length without taking account o£ the time lag, 

 or whether they prove the existence of the time effect, 

 requires further experimental and theoretical consideration. 



Our best thanks are due to Professor Nagaoka and also 

 to Professor A. Tanakadate for their kind guidance in carrying 

 out the present experiment. 



LXXII. On the Electrical Properties of Thin Metal Films. 

 By J. Patterson, B.A., Professor of Physics, Muir Central 

 College, Allahabad, India ; 1851 Exhibition Science Scholar, 

 Emmanuel College, Cambridge*. 



Introduction. 



THIS investigation was suggested by Longden's f experi- 

 ments on the electrical resistance of thin films deposited 

 in vacuo by the cathode discharge. From his experiments he 

 arrived at the following conclusions : — 



I. It was probable that the product of the resistance and 

 the thickness of the film was not constant, but increased very 

 rapidly with the decrease in thickness. 



II. The temperature-coefficient of very thin platinum films 

 was negative and within a certain range zero or negligible. 



III. The effect of artificial ageing on the film was propor- 

 tional to the magnitude of the temperature-coefficient. 



Miss Stone % had previously made some experiments on 

 silver films deposited by the " Rochelle salt process," and had 

 arrived at the conclusions : That the resistance of very thin 

 films was much greater than the calculated resistance, and 

 that heat decreased the resistance of the films, the rate of 

 decrease being much greater for the thin films than thick 

 ones. 



Vincent § quite recently has made very careful experiments 

 on the relation between resistance and thickness of silver 

 films deposited from a silver solution. He found that the 

 conductivity varied as the thickness down to 5 X 10~ 6 cm., 

 and below this thickness the conductivity decreased very 

 rapidly. 



* Communicated by Prof. J. J. Thomson. 



f Physical Keview, vol. xi. p. 40 (1900). 



\ Ibid. vol. vi. p. 1 (1898). 



§ Annates de Chemie et cle Physique, [7] xix. p. 421 (1900). 



