214 CARNEGIE INSTITUTION OF WASHINGTON. 



ELECTRIC-FURNACE INVESTIGATIONS. 



Besides some work in completing the examination of furnace spectra 

 of elements of the calcium group, the electric furnace, in connection 

 with the 15-foot concave-grating spectrograph, has been used for the 

 study of the manganese spectrum from X 2800 to X 6600, and for the 

 iron and titanium spectra, especially for the ultra-violet region as 

 far as X 2800 not covered in the work already published. About 60 

 furnace spectrograms have been made for various temperatures and 

 a considerable part of the work of examining and classifying the very 

 numerous lines of spectra has been done. This involves a comparison 

 with arc and spark spectra which have also been photographed for 

 these elements, and in the case of iron a comparison with the results 

 of Hemsalech for the flame spectrum. The grouping of lines in the 

 various sources and at the different furnace temperatures is very 

 pronounced, and special attention is paid to numerous lines which 

 are relatively strong in the furnace spectrum. 



Other work by Mr. King has been in connection with the cathode 

 luminescence spectra, the examination of the spectra of several 

 chemical samples, and tests of plates bathed with dicyanin. Solar, 

 arc, and furnace spectra as far as X 9200 were photographed with 

 plates thus sensitized, and it appears quite feasible to extend the 

 regular study of spectra to a limit still farther in the red by means of 

 these plates, 



PRODUCTION OF SPECTRA BY CATHODE LUMINESCENCE. 



The experiments by Miss Carter have been a continuation of previous 

 work, the method being to vaporize a substance through the impact 

 of cathode rays in a high vacuum and observe the spectrum given by 

 the vapor bombarded by the cathode stream. The considerable 

 heating of the apparatus in these experiments has introduced many 

 difficulties in addition to those usually met in working with high 

 vacua. The use of a quartz chamber, with most of the fittings of 

 the same material, was necessary on this account. In the later exper- 

 iments the spectra of iron, titanium, manganese, cadmium, and 

 magnesium have been produced by this method, and the previous 

 results for calcium checked by the use of a prism spectrograph. The 

 largest number of hues was obtained for manganese, about 125, while 

 about 100 hues of titanium were photographed. In distribution, the 

 luminescence spectrum is relatively rich in the ultra-violet, this being 

 the chief resemblance to the spark spectra. With calcium, cadmium, 

 and magnesium the method has brought out enhanced Unes, but with 

 other elements examined the spectrum is more like that of the arc. 

 The work is still in progress, and the material when completed may be 

 expected to show many features of interest. 



