52 A. W. Wright— Production of Transparent Metallic Films 



Platinum is volatilized with comparative ease, especially in 



familiar occurrence, as few of the common vacuum tubes which 

 have been subjected to the action of the induction coil for a 

 long time fail to show the effect. In a small tube the layer is 

 vtM •-.- bright, and is easily made thick enough to be quite opaque. 

 When sufficiently thin, it transmits light of a gray coir,., with 

 a slight bluish tinge. Palladium also is deposited in a thin 

 layer withoi, appears of a smoky brown color 



by transmitted light. Lead forms a very even film, with the 

 characteristic color of the metal, though it has but a compara- 

 tively feeble luster. Tt has a high degree of transparency, 

 — Tolor, inclining to an olive tint 

 fi of the oxygen and vapor 

 ui wBMre is necessary w> uie successful formation and preser- 

 vation of the film, as when exposed to the air or moisture it is 

 destroyed by oxidation in a very few minutes. 



Zinc and cadmium yielded brilliant mirrors, with a white, 

 silvorv luster. and appearing d.-ep grayish-blue by transmitted 

 light, with a barely noticeable inclination to purple. It is less 

 deep in tint than the light passed through silver, but deeper 

 than that from bismuth. There was no perceptible difference 

 between the two metals, unless it were a slightlv greater intens- 

 ity of the coloration in the case of the zinc. 



Aluminum was volatilized with considerable difficulty, re- 

 • e or six cells and a powerful coil. It formed a 

 ke film, which by transmitted light had a brownish 

 color, but the result was hot entirely satisfactory. Magnesium 

 yiel led even less readily, and showed no effect at all when tried 

 with the means which had given good results in the other cases. 

 It was necessary to reduce the electrode to a very fine wire and 

 this was enclosed in a tube of only 35 millimeters caliber. The 

 larger coil was used, and the power of the battery gradually 

 it> ' a.-ed to six Grove cells. Not the slightest effect was pro- 

 duced when a smaller number was employed, but after the ap- 

 p] tion of this power for a few minutes, the electrode was sud- 

 denly surrounded by a burst of green light, and the deposit was 

 formed almost instantly upon the glass. It had a brilliant lus- 

 ter, and when the light was seen through it, a grayish-blue color 

 that of zinc or cadmium, but less clear. 



Tin did not give very satisfactory results, as when the elec- 

 trode was made small enough for the purpose it was difficult to 

 avoid fusing it. The film when obtained was not as fine as 

 th oe e {.rod need with the other metals mentioned, but had in some 

 parts a sdvery metallic luster, and was sufficient to show that 

 when seen by transmitted light the metal appears of a brownish 

 gray or sepia tint . 



