electro-magnetic fields on the spark spectra of gold, etc. 87 



Wave-length 



X, 2651 '7.^ These lines show distinct widening — but they are too weak 

 2611*3.j to analyse. 

 2597 - 2. It shows a distinct widening; but the calcite did not 



separate it further. 

 2572*7. This line is rather weak, but it seems to show signs of 



widening. 

 2527 "6. A distinct widening; and, on analysis, it appears to be 



a triplet, with the two outer members vibrating parallel, 



and the inner one perpendicular, to the lines of force. 

 2477*3.) These lines show a distinct widening — but they are too 

 2444*8./ weak to analyse. 



With regard to the lines divided into triplets, it is seen that 

 of those arising from 3267-6, 32316, 3029, 2877*1, 25276, the two 

 outer members vibrate parallel, and the inner one perpendicular, 

 to the lines of force. On the other hand, of the triplet arising 

 from 3637*5, the two outer members vibrate perpendicular, and 

 the inner one parallel, to the lines of force. 



There are three lines on the plates and marked by Hartley 

 and Adeney as belonging to tellurium, which may be mentioned 

 here, namely : 



3382*0. A sharp, well-marked and weak line when the spark is 

 normal ; but when it is in the magnetic field there 

 appears to be no impression on the plate, even after 

 70 minutes' exposure. It may be due to a widening or 

 a division of the line which makes it too weak to affect 

 the sensitive plate. 



3273*0. This is a widened doublet or reversal. The separation is 

 well marked and sharply denned. 



3246*6. This gives a distinct widening. When analysed with the 

 calcite, it seems to be a triplet, with the two outside 

 members vibrating parallel, and the inner one perpen- 

 dicular, to the lines of force. 



Bismuth. 



4724*5 This line becomes a widened doublet or reversal. 



4301 *5. \ Two broad strong lines and they appear to be slightly 



4259*2. / widened. 



4121*2. The line becomes a triplet, with the two outer components 



vibrating perpendicular, and the inner one parallel, to 



the lines of force. 



ooeo >r I These are strong diffuse lines, and seem to show signs of 

 o~r>.T t I being; widened. 



VOL. XIII. PT. II. 7 



