Carnegie Institution of Washington Publication Volume 64-66 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 Excerpt: ...1 pi is due more to lack of polish and planeness of surface than to a possible transparent region such as obtains in silver, in the ultra-violet. Palladium is lower in reflecting power than platinum; and it is barely possible that it would have a slightly higher value if a better surface could be produced. The specimen was made by soldering a 0.1 mm. sheet upon a heavy plate of brass. Considerable difiiculty was experienced in casting a homogeneous plate of cadmium. Success was finally attained by melting it in a thin copper mold. When cool the mold was torn olf and the (1 cm. thick) plate filed and ground plane. In fig. 82 it will be noticed that its reflecting power suddenly rises to a constant value beyond 5 pi. The sheet of cobalt was about 0. 5 mm. thick, and permitted considerable filing and grinding. However, it was found impossible to prepare a surface that was free from pores. This probably explains its deviation in reflecting power from that of nickel, out to 10 pi, where it reflects more than nickel, as it should, since its electrical conductivity is higher. The aluminum was a sheet of commercial material. It took a high polish. Its reflecting power is unusually high beyond 10,1, and is known to be practically a perfect reflector for heat waves at 25,1. Little can be said concerning tin. It was found impossible to give it a polish, although the melted surface on cooling was very bright. From its electrical conductivity it ought to have a reflecting power of the order of nickel and platinum. Zinc is the most interesting of all the metals studied. It takes an unusually high polish which is quite permanent. Its color is peculiar. It seems to have a low reflecting power in the visible spectrum, which rises suddenly to a maximum beyond 4,1, and in thi...