Chemistry and Physics 43 



radical), which was described in No. 65, was definitely established. A minute ex- 

 amination of the reflection bands of quartz (crystalline and amorphous glass) and 

 of carbonates was made; and by means of residual rays the reflection spectra are 

 extended to the remote parts of the infra-red to wave-lengths 0.03 to 0.04 mm. 



In Part VI the transmission spectra of various solutions, of colloidal metals, and 

 of colored glasses are described, and the effect of special groups of atoms on radiant 

 energy is considered in detail. Part VII is an extension of Part II and describes 

 the arc and spark spectra of metals in hydrogen, to verify the previous work, which 

 showed that no strong emission lines exist in the deep infra-red. New and impor- 

 tant results were obtained on the vapors of the carbon arc. The radiation of the 

 Rubens thermopile to a vessel of liquid air was investigated, showing that the pile 

 is a very complete radiator and absorber of radiant energy. The Nernst glower is 

 shown to have a discontinuous spectrum at low temperatures, which becomes con- 

 tinuous at high temperatures. Various solids (many heated electrically, like the 

 Nernst glower) are shown to have discontinuous spectra with emission bands which 

 are as sharp as those of gases. 



The emission of the new metals (used in incandescent lamps) was investigated, 

 and it was found that the so-called "constants" of radiation are really functions of 

 the temperature and the wave-length. From a consideration of the reflecting power 

 it is shown that metals must emit selectively in the visible spectrum. The radiation 

 from selectively reflecting bodies, with special reference to lunar radiation, is 

 discussed. 



Three appendices are added, the most important one being on instruments and 

 methods used in radiometry, in which the radiometer, thermopile, radiomicrometer, 

 and bolometer are compared, both historically and by means of experimental data. 

 In each volume the author indicates problems requiring further investigation as well 

 as new fields of research. 



No. 164. COBLENTZ, W. W. A Physical Study of the Firefly. Octavo, 47 pages, 1 



plate, 14 text figures. Published .1912. Price $0.50. 



In this paper are discussed the production, the composition, and the functions of 

 the light emitted by fireflies. Luminous efficiency, candle-power, radiation, and 

 temperature measurements are given ; also data on the fluorescent substance found in 

 fireflies. The lights of various species of fireflies and of a standard lamp were 

 photographed, and the densities compared by means of spectrophotographic photom- 

 etry. In this manner the spectral energy curve of the light of the firefly was deduced 

 from a knowledge of the spectral energy curve of the standard lamp. It is shown 

 that the color of the light of the firefly is not a subjective phenomenon, the maxi- 

 mum emission of the Pyrophorus noctilucus being at 0.538/x, Phoiuris Pennsylvania 

 being at 0.522^,, Photinus pyralis being at 0.567/tt, Photinus consanguineus being at 

 0.578/*. 



No. 31. DAY, ARTHUR L., E. T. ALLEN, J. P. IDDINGS, and G. F. BECKER. The 

 Isomorphism and Thermal Properties of the Feldspars. Part I, Ther- 

 mal Study; by A. L. Day and E. T. Allen. Part II, Optical Study; by 

 J. P. Iddings, with an Introduction by G. F. Becker. Octavo, 95 pages, 

 26 plates, 25 text figures. Published 1905. Price $1.75. 



An investigation of the relation between the feldspars of the lime-soda series 

 undertaken partly in an endeavor to settle an old question of great petrological 

 interest and partly to establish the fact that minerals in solution with one another 

 differ in no essential particular from other solutions and obey the same funda- 

 mental laws. The materials are chemically pure feldspar types prepared in the 

 laboratory; the methods are those of quantitative chemistry, physics, and physical 

 chemistry, and the field covers the entire temperature range of teldspar formation 

 up to 1540* C. Many of the phenomena occurring at these extreme temperatures 

 differ widely from those commonly observed at ordinary temperatures and are thus 

 broadly interesting from the viewpoint of the properties of matter. In particular, it 

 was discovered that among the minerals it is not uncommon for the solid state to 

 persist for hours or even days at a temperature considerably above the melting-point, 

 a phenomenon which has never been observed before. 



