Carnegie Institution of Washington Publication Volume 97 (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. 1908 Excerpt: ...media. The only previous work done on this subject is due to Rubens, ' who examined the radiation from the Auer mantle, as well as mantles composed of the pure oxides of cerium and of thorium. The difficulty experienced by him was the elimination of the emission spectrum of the hot gases which was superposed upon that of the oxides composing the mantle. Hence, if he had examined a mantle of zirconium oxide he would not have been able to detect an emission band which occurs at 4.3 ft. 1 Paschen: Ann. der Phys. (3), 53, p. 26, 1894. The substances used in the present investigation were in the form of solid rods made in an oxy-hydrogen flame or in the form of thick layers of the substance placed upon a heater. The rods were heated by an electric current from the secondary of a 2000-volt (300-watt) transformer. These rods had, of course, to be heated initially with an alcohol or blast lamp until they became conducting, just as is necessary with the Nernst glower. The resistance placed in the primary circuit of the transformer to regulate the current, and the low capacity of the transformer, acted as a "ballast" to the radiating substances. The rods were provided with platinum terminals, sealed in the ends, and were securely mounted in incandescent lamp sockets. After heating them until they became conducting, they were mounted securely before the spectrometer slit. The substances that could not be melted and formed into rods were made into a paste and spread upon the "heater tube" of a Nernst lamp. The "heater tube" consisted of a hollow porcelain tube about 5 cm. long and 8 mm. diameter covered with a coil of fine platinum wire, and was used in preference to a platinum strip on account of its rigidity and ease in handling. It gave ...