MISCELLANEOUS COMPOUNDS. 



ROCK SAI.T (NaCl). 

 (/ = 3.n mm. Fig. 57.) 



The surfaces of this cleavage section were slightly blurred from 

 moisture, and the curve is given to show its great effect in the visible 

 spectrum, which becomes negligible in the infra-red. 



CALCITIC (CaCO 8 ). 

 (f = o.i4 mm.; cut 70 to axis. Curve a, fig. 58.) 



The section used was a small piece, 5 by 6 mm., made for polarimetric 

 work. It was too short to cover the whole slit, hence the actual trans- 



_U) 



7C 



C 

 ID 



U 



60 



50 



,< 







FIG. 57. Rock salt (c) ; Fluorite. 



mission is greater than 55 per cent, indicated on the curve. The curve 

 is remarkable for its transmission of heat-waves. After passing through 

 the opaque region at 7/x, the section is again fairly transparent to 14 ft. 

 There are bands at 3.44, 3.93, 4.6, 5.7, 6.5 to 7.5, 8.5, 9.4, 10, 10.7, 11.3, 

 12.2, 12.5, and 13. 2 /x. The region of great absorption at 3.4 to 3.9, 

 6-5 to 7.5, and 15 ;, are closely harmonic. 



It will be noticed that the CO, band at 4.28 is lacking, while the 4.6 p. 

 band, found in CO, is small, from which it appears that CO 2 , which is 



-., 



