A. E. Bostwick—Electrical Resistance of Metals. 138 
Art. XIX.—The Influence of Light on the ane! Resistances 
of Metals ; by AnTHUR E. Bostwic 
THE fact that light has an influence on the electrical resist- 
ance of the element selenium has been known since 1832, 
The discovery was made by Superintendent Mai of the Valen- 
tia cable station, and the results of a few experiments on the 
subject were communicated to the Royal Society by Lieutenant 
Sale* in March of the year above mentioned. Since that time 
ee property of selenium has received ta! investigation at 
e hands of Professor W. G. Adams, Dr. W. Siemens and 
sthere and some recent applications of it, more or less practical 
in their nature, have made it familiar. In connection with the 
experiments on selenium it has also been established that 
tellurium possesses the same quality of Ninotes its resistance 
affected by light, though in a much less 
The effect of light on these PSAs fe is we diminish their 
resistance. In the case of selenium this diminution has in some 
instances been found to amount to a large proportion of the 
entire resistance.t ‘Telluriam shows a diminution of less than 
One per cent, the greatest diminution obtained by Adams being 
one three-hundredth. t 
In the year 1877, Dr. Richard Bornstein of Heidelberg 
attempted to show that the property which had been establish 
in the case of selenium and tellurium was not peculiar to those 
substances, but was possessed in common with them by gold, 
silver, platinum, and probably by all other metals, though in a 
very much less degree. He announced as the result of his 
experiments that the effect of light upon gold, silver and plati- 
num was to diminish their resistance by from one and one-half 
hundredths of one per cent up to four per cent of the whole resist- 
auce. Shortly after this, Siemens] and Hansemann{ of Berlin 
undertook and co mpleted an investigation in which they were 
totally unable to detect any action like that described by Born- 
stein. The matter ae here until 1881, when Bornstein pub- 
lished** an account of a new series of experiments, from the 
results of which it cate” appear that the electrical resistance of 
silver is diminished one and one-fourth hundredths of one per 
cent by the action of light. As far as the writer knows, noth- 
ing more had been ae on the subject when he made the 4 
* Proc. Roy. Soc. Lond., May, 1 
C, E. a iggy oN a New For ges Selénium Cell ;” we Journal, Dec., 1883. 
Proc. Roy. d., June Tt, Biddy and Jan. é, 187 
Phil. Mag., V, vol. iii, 1877, p. 
Berlin Monatsberichte, June, ete Ibid. 
* Carl’s Repertorium, xvii Bd., 2 und 3 heft, S. 164. 
