﻿202 M. F. Zollner on the Influence of Density and 



parts of the spectrum considered was diminished from 20 to 1*1 

 by increase of the pressure from cr = l to cr=500. But now let 

 these two values be supposed 5 times as great, thus, 



A A = 0-500, 

 A A =0025, 



we then obtain the following series of ratios of intensity for dif- 

 ferent values of a : — 



A A = 0-500 A A =0-100 



°"' A A =0-025 A A =0-005 



1 20-0 20-0 



10 4-5 13-3 



20 2-5 9-2 



40 1-6 5-3 



80 M 3-0 



Here, then, the ratio of intensity, starting from the same 

 value, reaches the small value 1*1 at a pressure less than one 

 eighth part of that requisite with a lower value of the absorptive 

 power. 



The results last obtained may be expressed in the two follow- 

 ing theorems : — 



The greater the absorptive power in two adjacent parts of a 

 spectrum, the more quickly does the ratio of their intensity change 

 with the density. 



Taking into account the generally greater values of the ab- 

 sorptive power at higher temperature, it hence follows further 

 that, 



The higher the temperature of the incandescent gas, the more 

 quickly is a discontinuous spectrum converted into a continuous one 

 by increase of the density. 



By the aid of the first theorem, from the great changes un- 

 dergone by a certain line in a spectrum (for example, the hy- 

 drogen-line F) through alterations of the pressure, relatively 

 great values of the absorptive power in that part of the spec- 

 trum may be inferred, provided that we duly consider the dif- 

 ference of the dispersion in the various parts of a spectrum pro- 

 duced by refraction. 



From the second theorem it follows that, the density remain- 

 ing the same, a discontinuous spectrum can be converted into a 

 continuous one by a sufficient increase of the temperature of the 

 incandescent gas. This consequence is confirmed by Wullner's 

 observations, in which, with equal magnitudes of the pressure, 

 discontinuous spectra corresponded to the weaker discharges, 

 and continuous ones (or altered in that direction) to the stronger, 



