NOV. 4, 1921 abstracts: physics 439 



may be converted into the soluble form by grinding and heating with 

 sulfuric acid, a commodity readily available at western smelters. 



It remains to be determined what rate of application of aluminum 

 sulfate will be required for different alkali soils. Marked improvement 

 in permeability to water and in physical condition on subsequent dry- 

 ing have been noted from applications at the rate of one ton per acre 

 while much heavier applications have not shown any deleterious effect 

 on subsequent crop growth. It is believed that the discovery of the 

 beneficial effect of alum on alkaline irrigated land opens a wide field 

 of investigation in this perplexing subject. 



ABSTRACTvS 



Authors of scientific papers are requeste 1 to see that abstracts, preferably prepared 

 and signed by themselves, are forwarded promptly to the editors. The abstracts should 

 conform in length and general style to those appearing in this issue. 

 PHYSICS. — The present status of the constants and verification of the laws of 



thermal radiation of a uniformly heated enclosure. W. W. CoblENTz. 



Bur. Standards Sci. Papers 17: 7-i8. (No. 406.) 1921. 



An examination is made of the instruments, methods, and experimental 

 data pertaining to various determinations of the constant, (x, of total radiation 

 and the constant, c, of spectral radiation of a black body. After making 

 obvious corrections for reflection from the receiver and for atmospheric ab- 

 sorption, the determinations of various experimenters are in close agreement, 

 giving a value of o- = 5.72 X 10 ~^ ergs, and c = 14320 micron degrees. W. W. C. 



SPECTROSCOPY. — Wave-length measurements in arc spectra photographed 

 in the yellow, red and infra-red. F. M. Walters, Jr. Bur. Standards 

 Sci. Papers 17: 161-177. (No. 411.) 1921. 



For several years the Bureau of Standards has been conducting grating 

 measurements in red and infra-red arc spectra by the aid of specially sensitized 

 photographic plates to improve the data and to find some element which 

 would furnish lines suitable for wave-length standards in this region. To 

 the measurements on 25 elements already made, the following are here added : 

 Silver, Aluminum, Gold, Bismuth, Cadmium, Mercury, Lead, Antimony, 

 Tin, Zinc. The wave-length measurements are in the international system 

 and are given to 0.01 A. 



The elements were brought to luminosity by inserting a sample in copper 

 or graphite electrodes between which the arc was maintained. The grating 

 used had 297 lines per mm. and a 640 cm. radius. The spectra were photo- 

 graphed in the first order on plates sensitized with pinacyanol or dicyanin. 

 The comparison spectrum was iron in the first, second, or third order, and in 

 the reductions the wave-lengths established by interference methods were 

 used. F. M. W. 



PHYSICS. — The use of the Ulbricht sphere in the measurement of reflection 



and transmission factors. Enoch Karrer. Bur. Standards Sci. Papers 



17:203-225. (No. 415.) 1921. 



A brief historical survey is given of the methods and instruments used in 



measuring the reflection factor of surfaces. The various ways in which the 



