44 Rubens and Trowbridge — Dispersion and Absorption 







Table IV. 





Wave length. 



Fluorite 

 d = 3-40. 



Chloride of silver. 

 d = 3-08. 



Hock salt 



Sfx 



89*5 



40-5 



92*0 



9 



77*0 



44*8 



91-5 



10 



51-5 



51-5 



909 



11 



19-8 



55 



92-0 



12 



2-07 



57'8 



92*0 



13 



o-o 



59-2 



905 



14 







60*2 



90-5 



15 





59'9 



89-5 



16 







63-8 



85*6 



17 







67-8 



74-7 



18 











63-7 



19 







679 



39*1 



20*7 







64-7 



J 3-4 



23-7 



.... 



28*0 

 Table V. 



11 



Wave length 



A. 



Rock-salt. Sylvine. 



Thickness of layer = l cm 



Fluorite 



*n 











84'4 



9 



995 



100-2 



54-3 



10 



99-5 



98-8 



16'4 



11 



99-5 



99-0 



1-0 



12 



99-3 



99-5 



o-o 



13 



97-6 



99-5 



_ 



14 



93*1 



97*5 







15 



84-6 



95*4 







16 



66-1 



93-6 







17 



51-6 



92-2 







18 



27-5 



86*2 







19 



9-6 



75-8 







20-7 



0-6 



58-5 







23-7 







15-5 







On the other hand, we did not calculate values for a layer of 

 chloride of silver l cm thick, as the chloride of silver plates 

 used by us were not sufficiently clear and homogeneous to 

 seem to us to permit of the application of the law of absorp- 

 tion, with even the roughest approximation. For light rays, 

 the plate was almost completely turbid, so that the increase in 

 its transmission for increasing wave lengths in the field 

 between X — Sfi and X = 18/^, may possiblybe only attributable 

 to the similar* peculiarities observed by Angstrom for turbid 

 media. The transmission, as a function of the wave length, of 

 a layer l cm thick of rock salt, sylvine, and fluorite, is given 



* K. Angstrom, Wied. Ann., xxxvi, p. 715, 1889. 



