GASES IN VACUUM-TUBES. 



315 



in figure 145, where curve a is for a pressure of 0.3 mm. and b for a 

 pressure of 0.8 mm. There seems to be a sHght trace of radiation 

 throughout the spectrum, but no strong Hues are found except the one 

 at 4.75 II. 



An examination of this band was made for a constant current of 

 0.2 ampere and variable pressure. The results are given in figure 146, 

 in which the abscissje are pressures in millimeters of mercury and the 

 ordinates are deflections in centimeters. It is to be noticed that the 

 intensity of the CO band is much greater than that of CO, for all 

 pressures, the current of 

 0.02 ampere being the 

 same for both gases. 

 Moreover the intensity 

 does not pass through a 

 maximum, as is true of 

 the H and N lines Ivins: 

 near the visible spec- 

 trum. The greater in- 

 tensity of CO vv^ould 

 make it appear as though 

 the 4.75 [J. band were due 

 to this gas. 



Ethyl Alcohol (CgHsOH). 



Ordinary absolute 

 ethyl achohol was used. 

 It was introduced into 

 the previously exhaust- 

 ed pump through an es- 

 pecially provided bulb 

 and stopcock. The em- 

 ission curve (fig. 147) 

 is very unusual. It 

 shows no distinct lines 

 except the strong band 

 at 4.75 fx., which is to be found only in CO and CO,. The continuous 

 spectrum from 2 to 4 ^ is difficult of explanation. Possibly it is a 

 composite of bands of alcohol vapor and the water-vapor bands found in 

 the Bunsen flame. In the latter, however, the bands are in groups, with 

 regions of zero radiation. The bands at 4.75 ^ indicate a dissociation 



Fig. 146. 



