ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded promptly to the editors. 

 Each of the scientific bureaus in Washington has a representative authorized to 

 forward such material to this Journal and abstracts of official publications 

 should be transmitted through the representative of the bureau in which they 

 originate. The abstracts should conform in length and general style to those 

 appearing in this issue. 



PHYSICS. — The reflecting power of tungsten and stellite. W. W. Cob- 

 lentz and W. B. Emerson. Bureau of Standards Scientific Paper 

 No. 308 (Bull. Bur. Stds., 14:307-316). 1917. 



The reflecting power of tungsten and stellite in the region of the 

 spectrum from 0.5 /z to 6ju was determined by comparison with silver, 

 and by a new method employing a total reflecting prism. Four 

 samples of tungsten in the form of plane, highly polished mirrors were 

 examined. The reflectivity of tungsten rises abruptly from 50 per cent 

 at 0.5 ix to 90 per cent at 2/j, 



All samples of tungsten show sharp indentations at 0.8 n in the 

 reflectivity curve. A similar indentation occurs at 1.3 ju in the reflec- 

 tivity curve of the pure metal, but not in an impure sample. The 

 application of these data to the question of increasing the luminous 

 efficiency is discussed. 



The reflecting power of stellite rises from 65 per cent in the visible 

 spectrum to 88 per cent at 9/jl. W. W. C. 



PHYSICS. — Standard samples for thermometric fixed points. Bureau 

 of Standards Circular No. 66. Pp. 19. 1917. 



This circular describes the methods of preparation and the chemical 

 analyses of the metals tin, zinc, aluminium, and copper, which have 

 been prepared by the Bureau of Standards for distribution. 



The melting points of these materials were determined with platinum 

 resistance thermometers, and will serve to define accurately certain 

 fixed points of the temperature scale so that they may be used for the 

 calibration of pyrometers, the samples distributed being sufficient in 

 amount (about 50 cm. 3 ) for this purpose. 



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