December 31, 1920] 



SCIENCE 



637 



DISCUSSION AND CORRESPONDENCE 



HIGH TEMPERATURES AND EMISSION FROM 

 GASES 



In view of the discussion between Dr. A. S. 

 Kingi and Dr. G. A. Hemsalech^ upon the 

 origin of the spectra obtained in the carbon 

 tube fiu-nace, it may be of interest to call 

 attention to the complete absence of emission 

 lines in mercury vapor, argon, nitrogen and 

 hydrogen, when heated to 3200° K. by means 

 of a tungsten filament. 



Observations of the heated zone adjacent to 

 the filament while shielding the spectroscope 

 slit from the filament radiation have shown 

 no evidence of emission in the visible region 

 from any of the above gases. 



Professor F. A. Saunders was kind enough 

 to photograph the spectnam from a tungsten 

 spiral at 3200° K. operating in mercury vapor 

 at approximately atmospheric pressure in a 

 quartz bulb. He obtained no trace of emis- 

 sion lines, but did find an absorption at A. 2536. 



The potential gradient along the wires 

 varied from about 1.5 volt per centimeter in 

 mercury vapor to 15 volts cm. in hydrogen. 



These results suggest that the spectra ob- 

 tained in the carbon tube furnace are neither 

 primarily dependent upon potential gradient 

 nor temperature, but are probably more of the 

 nature of flame spectra produced by chemical 

 reactions between the various elements pres- 

 ent in the tube. 



Gr. M. J. Mackay 



Reseakch Laboeatokt, 

 General Electric Co., 

 Schenectady, N. T. 



a possible relation between mechan- 

 ical, electrical and chemical 

 quantities 



To THE Editor of Science: In my note in 

 your issue of November 26, page 509, on " A 

 possible relation between mechanical, electrical 

 and chemical quantities " ( ?), I regret that by 

 an oversight I omitted to add that this rela- 

 tion applies to a valence of unity, as it is in 

 the case of silver, which element was used in 



■i^ Astrophys. Journal, 52, 187, October, 1920. 

 2FUI. Mag., 36, 209, 281, 1920; 39, 241, 1920. 



deducing it. For any other valence the atomic 

 weight must of course be divided by that par- 

 ticular valence. 



Gael IIering 

 Philadelphia, 

 December 2, 1920 



REQUEST FOR SEPARATES 



In a note from Professor A. Dehome, of 

 the Institute de Zoologie, Universite de Lille, 

 France, it is stated that the straitened 

 financial circumstances of the university li- 

 brary at Lille permit the purchase of but few 

 biological publications. La Cellule, for ex- 

 ample, being the only cytological journal re- 

 ceived. In accordance with Professor De- 

 horne's request, may I urge cytologists and 

 other workers in biology to send him sepa- 

 rates of their published articles, and thus 

 contribute to the development of biology at 

 Lille. Such contributions can easily be made, 

 and they will surely be appreciated very 

 highly. 



Lester W. Sharp 



an appeal for publications for 

 czechoslovakia 



"Within the two brief years of its existence 

 the new Czechoslovak Eepublic has established 

 two new universities — one at Brno (Briinn) 

 and the other at Bratislava (Pressburg), be- 

 sides a series of high schools and several thou- 

 sands of common schools. In addition, the 

 University of Prague finds itself this year 

 with a nearly redoubled number of students, 

 of whom there are now over 10,000. With the 

 generally and greatly reduced exchange value 

 of European currency, it has become exceed- 

 ingly difilcult for the scientific men of these 

 universities to provide themselves with litera- 

 ture published since 1914, and they appeal to 

 their American colleagues for help in this 

 direction. The publications needed are those 

 reporting original research in all branches of 

 science. Sets of reprints of individual in- 

 vestigators, and periodicals, will be particu- 

 larly valued. Besides these, however, any re- 

 prints or scientifically valuable volumes that 



