﻿280 Mr. A. L. Fletcher on the 



fused in a bed consisting of a mixture of 7 grams of borax 

 and 20 grams of a mixture of sodium and potassium 

 carbonates, showed a very markedly increased yield by the 

 addition of radium-free boracic acid. Again, in the examin- 

 ation of the finer particles of a soil, the addition of about 

 15 grams of borax, conferring fluidity upon an otherwise 

 typically " dry " melt, and accompanied by a greatly in- 

 creased effervescence, raised the result by over four times in 

 one case, and three times in another. It was found that 

 fusion, even of an acid rock powder with borax alone as a 

 flux, was not in the absence of free effervescence capable of 

 completely deemanating the melt. 



It was judged desirable to attempt to approximate 

 throughout as regards fluidity and effervescence to the 

 conditions under which the standardization experiments 

 were performed, rather than to differentiate between the 

 slightly varying constants obtained with different rocks, in 

 view of the slight and very uncertain nature of these 

 variations. 



The above conditions do not appear to be always necessary 

 in the case of the purer Calcareous rocks, and seven experi- 

 ments failed to detect a connexion between fusion conditions 

 and yield of emanation. The White Jura Limestone from 

 Wurtemburg yielded the same low figure, viz. 0*3 X 10~ 12 gr. 

 per gram for the radium content quite irrespective of wide 

 changes in the chemical nature of the fusion mixture. 

 Again, two experiments on a very pure chalk which yielded 

 a very "dry" melt when simply fused with carbonates, 

 showed no appreciable rise when twice repeated with the 

 addition of boracic acid, although in the first instance the 

 evolution of carbon dioxide was very slight and in the latter 

 case extremely violent. 



An explanation is probably forthcoming, in the early break 

 up of the Ca00 3 molecule in this class of rocks before 

 fusion temperature is attained, involving the liberation of all 

 the emanation independently of questions of effervescence or 

 melt fluidity. It was indeed found that the mere heating of 

 a limestone without the admixture of any chemicals was 

 sufficient to very largely deemanate the rock powder. 



Chemicals involved. 



A few experiments were made to ascertain the most 

 efficient chemicals having regard to the most desirable 

 conditions of the melt, attained subject to the conditions 



