some Carbonates of the Calcite Group. 



335 



^ = A X 6 for X > X A and 

 P 



£ = A ; X h for X < X A 

 P 



where - is the uncorrected (for scattering, which actually 



p 

 is quite negligible here) mass absorption coefficient. A 

 and A' are constants for a particular atomic number Z and 

 are roughly linear logarithmic functions of the atomic 

 number, b is constant for a particular element and has 

 values for different elements lying between 2.55 and 2.90. 









/ 



T 7^ 



mm 









/ 



'/$& 









/,/ 



30/ 







A 



/// 



ill 



! / j 







i 

 1 





/ 





/ / 

 // 

 / / 



I 



it 







/ / 



/ 









/ / 



/ / i 



/ 







A 



' / 









1 



/ 











I 









.2 A .6 .8 1.0 



WAVE LEN6TH 



Fig. 11. — The mass absorption coefficient- wave length curves for silver, 

 bromine and silver bromide. 



On this basis the absorption curve for silver can be writ- 

 ten, knowing that A = 66, A' = 389, b = 2.65, and A A the 

 critical absorption wave length of silver, = 0.49 X 10 -8 cm. 

 This curve is shown in lig. 11. The information concern- 

 ing the absorption of bromine is meager, but assuming the 

 above relations, an approximation to its absorption curve 

 can be obtained. 



A = 0-004 Z 314 , A' = 0-0195 Z 2 ' 5S ; X A = 0-93 x 10" 8 cm. ; aa 



23 E. Glocker, Phys. Zeit. 19, 66, 1918. 



