368 Mr. J. Crosby Chapman on 



From measurements of this curve it can be shown at once 

 that the total energy of the radiation produced in the gold 

 leaf by the tin radiation is absorbed to the extent of 52 per cent, 

 (approximately), when it passes through a thickness of gold 



Fig. 2. 



SO 



60 



$40 

 N 



20 



- %- 



.]_ 



2 4 6 3 jo 



No OF LEAVES SERViNQ A? CORPUSCuL^ ,? itAtiJATCf? 



equivalent to one leaf. Since the absorption of corpuscular 

 rays in one gold leaf is 52 per cent., this means that half that 

 thickness w T ill absorb something of the order of 30 per cent. 

 Arithmetical calculation gives the following figures when 

 one gold leaf is considered. 



Gold leaf thickness = 9*9 to 10*1 x 10" 6 cm. 



Corpuscular radiation produced by tin characteristic rays. 



Energy of corpuscular radiation emerging from gold leaf _ iD 

 Total energy of corpuscular radiation produced in gold leaf — 



And this was the fraction it was required to determine. 



The following results should be stated as showing the 

 smallness of error due to absorption of the gold X-radiation 

 by the paper and gold leaf. 



Percentage absorption of gold fluorescent radiation by: — 



(1) A single thickness of paper = *7 per cent. 



(2) A single thickness of gold leaf =2*0 „ 



