the Griffin of Radium. 603 



as soon as the decomposition of the mineral was completed. 

 The tube attached to the reservoir B was disconnected, and a 

 lighted burner was placed under the flask A. The water in 

 the flask A was boiled for about five minutes, the steam being 

 permitted to escape through the side tube a. The pinch- 

 cock a was closed and the pinchcock b was opened, the steam 

 from the flask A passing into the flask C. The pinchcock c 

 was opened, and the gases were driven from the flask C into 

 the burette D. The boiling of the water in A was continued 

 until no further accumulation of permanent gases could be 

 detected in the burette D. This portion of the operation 

 required about 20 minutes, and the gases as they accumulated 

 in the burette D were transferred to the storage burette. 

 When the last of the gas had been transferred to the latter 

 burette, it was treated with a small quantity of strong sodium- 

 hydroxide solution which removed the remaining carbon 

 dioxide. The residue of gas was usually from 50 to 100 c.c. 

 in volume, and consisted chiefly of air which had been 

 intentionally left in the flask C. It was allowed to remain 

 in the storage burette for about 15 minutes, and was then 

 transferred through a tube containing drv calcium chloride 

 to an air-tight electroscope. At the end of three hours the 

 activity of the emanation in the electroscope was measured. 

 The observed activity of the emanation, expressed in terms 

 of the number o£ divisions of the scale passed by the gold- 

 leaf in one minute, was divided by the weight of the sample 

 taken, and gave the activity of the emanation from one gram 

 of the substance under investigation. The sum of the activity 

 of the emanation thus obtained from one gram of the sample 

 plus the activity of the emanation spontaneously evolved 

 from one gram of the sample at ordinary temperatures, gave 

 the activity of the total or equilibrium quantity of emanation 

 corresponding to the radium contained in one gram of the 

 material tested. 



The analytical determination of the uranium in the minerals 

 was conducted as follows * : — 



The minerals soluble in dilute acids were treated with 

 either pure, dilute (1:1) hydrochloric acid, or with dilute 

 hydrochloric acid containing a little nitric acid. The 

 >(.lution was evaporated to dryness and heated until the 

 acid was driven off. The residue was moistened 

 with concentrated hydrochloric acid, water was added and 

 the liquid was heated to boiling. The residue of silica was 

 filtered off, and the filtrate was treated with an excess of 



* The method used u a modification of that described by Brearley,. 

 • Analytical Chemistry of Uranium,' L903, 



2R2 



