A. G. Bell—Production of Sound by Lnght. 305 
be different. On the other hand, it resembles a star in other 
brightest stars. 
Cambridge, U. S., Sept. 7, 1880. 
Art. XXXIV.—On the Production and Reproduction of Sound 
y Light; by ALEXANDER GRAHAM BzxL, Ph.D. 
[Read before the American Association for the Advancement of Science, in Bos- 
ton, August 27, 1880.] 
ts 
I shall first describe that remarkable substance “selenium,” 
and the manipulations devised by previous experimenters ; but 
the final result of our researches has widened the class of sub- 
stances sensitive to light vibrations, until we can propound 
the fact of such sensitiveness being a general property of all 
matter. 
We have found this property in gold, silver, platinum, iron, 
steel, brass, copper, zine, lead, antimony, german-silver, Jenk.. 
in’s metal, Babbitt’s metal, ivory, celluloid, gutta-percha, hard 
rubber, soft vulcanized rubber, paper, parchment, wood, mica, 
and silvered glass; and the only substances from which we 
have not obtained results, are carbon and thin microscope 
glass.* 
* Later experiments have shown that these are not exceptions. 
Am. Jour. — i Serizs, Vou. XX, No. 118.—Ocr., 1880. 
