210 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 9 



PHYSICS. — The variation of residual induction and coercive force with mag- 

 netizing force. R. L. Sanford and W. L. Cheney. Bur. Standards 

 Sci. Paper 384. Pp. 10, figs. 6. 1920. 



This paper is a report of an investigation to ascertain whether or not 

 analytical expressions similar to the reluctivity relationship of Kennelly 

 correctly represent the variation of residual induction and coercive force with 

 the maximum magnetizing force. Hysteresis measurements were made on 

 a number of samples covering a wide range of material using magnetizing 

 forces up to 2500 gausses. The relationships Hm/Br = Oi + 6iHm and 

 Hm/Hc = a-j + h{H.,n were found to hold within the limits of the probable 

 experimental error. W. L. C. 



SPECTROvSCOPY. — Relative spectral transmission of the atmosphere. B. 

 Karrer And E. P. T. Tyndall. Bur. Standards Sci. Paper 389. Pp. 

 37, figs. 20. 1920. 



Data on the relative spectral transmission are given, (1) for a clear atmos- 

 phere, (2) for the atmosphere of high humidity, and (3) during rains. The 

 curves for (1) show little selectivity. Between wave-lengths 520 and 6G0 m/x 

 the transmission is uniform. At 6G0 it begins to decrease. Also from 520 to 

 440 m^t it gradually and continuously decreases. The curves for the atmos- 

 pheric condition of (2) and (3) are almost identical for the region from 430 

 to 560 m/x, the transmission increasing with the wave-length. In the region 

 from 560 to 670 mju the curve for the rainy atmosphere shows a maximum 

 near 640 m/x, while that for the atmosphere of high humidity indicates two 

 maxima, at 5S0 and at 650 m^t, with a miminum near 620 m/x. The de- 

 crease at 660 mju in both cases is very similar to that noted for the clear atmos- 

 phere, and is probably to be associated with the absorption band of the oxygen 

 of the atmosphere. E. K. 



SPECTROvSCOPY. — Wave lengths longer than 5500K in the arc spectra of seven 

 elements. C. C. KiESS and W. F. Meggers. Bur. Standards Sci. 

 Paper 372. Pp. 29, fig. 1. 1920. 



The concave grating spectrograph of the Bureau of Standards was used 

 to photograph the yellow, red and infra-red arc spectra of titanium, vanadium, 

 chromium, manganese, molybdenum, tungsten and uranium. This work is a 

 continuation of a program of standard wave-length determination and spec- 

 troscopic analysis which has as one of its objects the mapping of the spectra 

 of chemical elements as far out into the region of long wave-lengths as modern 

 photographic methods will permit. 



The spectrograms were made on photographic plates sensitized to the 

 long waves by bathing in solutions of dyes. Recently "made-in- America" 

 dyes were used for many of the plates and were as effective in their photo- 

 sensitizing action as the imported ones. The wave-lengths of more than 

 2500 spectral lines were derived from the measurement of the plates. These 

 wave-lengths extend from the green at 5500 A into the infra-red beyond 

 9700 A. So far as known, impurity lines and spurious lines have been 

 eliminated from the wave-length tables. Frequency dififerences which are 

 suspected of being constant have been found in each of the spectra here pre- 

 sented. C. C. K. 



