816 Mr. H. Smith on the Spectroscopy of the Electric 

 Zinc Sulphate, 

 The lines due to zinc are : — 



1st Sub-series. 2nd Sub-series. 



(3282 2802 2771 (4680 ( 3072 



-> 8303 \ 4,722 -? 3034 



(3346 (4811 ([3019] 



The arc line 6364 is very weak, while spark lines appear 

 faintly at 2502, 2558, 4912, 4925. 



Lines also appear at 424, 465, 450. These occur in the 

 vacuum-tube discharge, in the arc in hydrogen, and in the 

 arc in vacuo. 



From the intensities of the spectral lines which appear, 

 it will be seen that the spectrum is intermediate between the 

 spark and the arc spectrum. 



Magnesium Sulphate. 

 The lines due to magnesium are : — 



1st Sub-series. 2nd Sub-series. 



f3838 2X52 f5184 3332 



■} 3833 ] 5173 



(3830 (5168 



The spark-line at 4481 appears but is rather faint. The 

 lines of the isolated series 5529, 4703, 4352, 4058 are 

 absent. This series is bright in the arc. The spectrum of 

 magnesium, like that of zinc, is intermediate between the 

 spectra of the arc and spark. 



A series of bands appears in the ultra-violet between the 

 limits 380 and 368. A band spectrum between these limits 

 occurs which is ascribed by some to magnesium oxide and by 

 others to magnesium. The bands were so crowded on the 

 negative that any closer identification was impossible. The 

 green bands of magnesium oxide were absent. 



Oxygen. 



The elementary line spectrum appears in the brush under 

 certain conditions. In distilled water it appears in the 

 spectrum of each brush, but very faintly in comparison with 

 the hydrogen lines. A slight increase in conductivity causes 

 the spectrum to disappear from the negative brush, while it 

 is strengthened in the positive. As the brush passes over 

 to the solution type, the oxygen lines are further strengthened 



