98 



INFRA-RED EMISSION SPECTRA. 



Orthoclase (var. Adularia) [KAlSisOs]. 



(Rod 8 mm. long, 2 mm. diameter. Energy supplied, 6.2 and 8.9 watts. Curves a and b, 

 respectively, of fig. 64. Transmission, Carnegie Publication No. 65, p. 64.) 



This substance emitted a little more light than albite, although it was 

 more transparent. The emission band at 2 j.i is prominent. The one at 



/ 2 3 4 5 6 7 8U 



Fig. 65. Orthoclase (a); alumina and silica (6); alumina and feldspar. 



2.88 n is shifted from its position at 3.2^ in the absorption spectrum, 

 from which it would appear that the group of atoms causing the absorp- 

 tion is different in the two cases. An examination of the transmission 

 spectrum using polarized light will be necessary to determine the true 



