324 Scientific Intelligence. 



The study of the subject has been an exceedingly extensive and 

 thorough one, and the results are reported in a very excellent 

 manner. There is a very elaborate classification of the different 

 positions in chemistry, showing the varied character and wide 

 scope of the work. The prejudices to be met by women, the 

 training requirements, salaries, means of obtaining positions, and 

 many other topics connected with chemical work are well dis- 

 cussed. 



The book is to be highly recommended for the perusal of 

 women students who are attracted by the study of chemistry and 

 are considering making a specialty of the subject. It is an excel- 

 lent book also for those who give advice to such students, and it 

 may be added that young men who are prospective chemists can 

 find in it much valuable information in regard to chemical 

 positions. h. l. w. 



5. Spectrum of Aurora. — In making the extended series of 

 photographs of all light of the night sky reported in this journal 

 3, 476, 1922, Lord Raleigh was fortunate in securing spectra of 

 the aurora which show more detail than has been obtained in any 

 previous photographs, but, except for the aurora line 5578 of 

 unknown origin, the whole spectrum is accounted for by three 

 groups of bands in the blue, the violet, and the ultra violet which 

 have been proved by Bossekop to be negative nitrogen bands. 



As the origin of this phenomenon has never been fully 

 explained Rayleigh 7 s study and attempt to reproduce these bands 

 artificially are worth reporting. 



A large tube through which a stream of rarefied nitrogen could 

 be passed was prepared and arranged so that the various features 

 of the cathode discharge could be isolated and their spectra sep- 

 arately photographed. The sources of light were four. (1) The 

 pencil of cathode rays, which could be easily deflected by a weak 

 magnetic field. (2) The undeflected or so-called "retrograde" 

 rays which may be designated as atomic rays in distinction 

 from (1) which are electronic. (3) The negative glow. (4) The 

 so-called dark space which really emits some light and is only 

 dark by comparison. 



It was found that the relative intensities within the blue and 

 violet groups of bands vary with the different kinds of excitation 

 and that this difference was most conspicuous within the blue 

 group. The point under examination was to determine which 

 mode of excitation most closely approximated the relative inten- 

 sity of these bands in the auroral spectrum. It was found that 

 these intensities in the cathode rays, the negative glow and the 

 dark space gave no approximation to the auroral conditions but 

 the atomic ray spectrum did exhibit about the same intensity 

 ratios as the spectrum of the aurora. 



Numerous experiments on variation of pressure were tried as 



