the Rocks of the Transandine Tunnel, 39 



(4) Standardized from the alkaline solution derived from 

 10 grams Keuper Sandstone, fused with 24 grams mixed 

 carbonates, in 600 c.c. distilled water ; leached and filtered 

 clear, which when tested gave a gain of 4 scale- divisions 

 per hour. To this was added '2 m.g. uraninite, standard 

 solution. Closure 14 days, i. e> 92'7 per cent, emanation 

 collected. 



Gain = 6 5' 5 scale-divisions per hour. 

 True gain = 70*7 „ „ 



if closed till radioactive equilibrium was established. 

 Hence 



Gain due to added radium = 66*7 scale-divisions per hour, 



whence C = -61xl0- 12 . 



The constant will be somewhat higher if we assume the 

 normal leak the same for both experiments, when 



2nd leak— 1st leak = gain for added radium. 



This comes out as 62 scale-divisions per hour, and 



C = '65xl0" 12 . 



(5) Standardized from an alkaline solution obtained by 

 fusing 20 grams basalt in 120 grams carbonates, dissolving 

 in distilled water, leaching and filtering. 



This was found to contain 3 x 10 -12 gram radium by 

 preliminary experiments, using the constant 0'6 X 10~ 12 . 



To this was added '2 m.g. uraninite from standard solution, 

 so that the total radium present was 



43-5 x 10- 12 + 3 X lO" 12 gram = 46'5 x 10~ 12 gram. 



Closure 20 days. Gain 63' 7 scale-divisions per hour. 



46-5 xlO -12 



Hence C = * ' = 0-73 x 10~ 12 . 



bo* ( 



If again we calculated by the difference in gain of rate of 

 discharge in the 1st experiment (5 scale-divisions per hour) 

 and in the 2nd experiment (63*7 scale-divisions per hour), we 

 get the 



Gain due to radium = 58*7 scale-divisions per hour. 



Hence C - 43 " 5 .** 0- " - Q-74xlQ-» 



ob'l 



