AMERICAN 
JOURNAL OF SCIENCE AND ARTS. 
[THIRD SERIES] 
Art. XXIIL.—On a new Process for the Electrical Deposition 
of Metals, and for constructing Metal-covered Glass Specula ; 
by Professor ArTHUR W. Wriaut, Yale College. 
Ivy a paper by the writer, published in this Journal, Janu- 
ary, 1877, an account was given of a method of producing me- 
tallic films upon the inner surface of exhausted glass tubes, by 
the action of a succession of energetic electrical discharges. 
The thickness of these films could be varied, from a tenuity 
such that the coating barely gave indications of a metallic lus- 
ter, and scarcely dimmed the intensity of transmitted light, to 
the point where perfect opacity was attained, by simply. con- 
tinuing the action of the current for a shorter or longer time. 
They were produced by forming the negative electrode of the 
metal to be deposited, exhausting the tube, and passing 
through it the current from an induction coil. The metallic 
coatings thus obtained, as seen from the exterior, were very 
brilliant, but the condition of the inner surface was not readily 
rved, and the nature of the process made it seem proba- 
ble that they possessed a dull or eyen a frosted surface. With 
a view to obtain the films in a tter suited for examina- 
as the nearer portion of the platgmieceived a larger share of 
the metal, the thickness of the de vas not: uniform, and it 
Am. Jour. 8c1.—Tuirp _— Vou, X 
