58 Mr. H. H. Poole on the Rate of 



the simultaneous evanescence of two BesseFs functions 

 requires that the common root be such that z* satisfies an 

 algebraic equation whose coefficients are integers, the degree 

 of the equation rising with the difference in order of the 

 functions. If, as seems probable, a root of a BesseFs 

 function cannot satisfy an integral algebraic equation, it 

 would follow that no two BesseFs functions have a common 

 root. The question seems worthy of the attention of 

 < mathematicians. 



/ 



IX. On the Rate of Evolution of Heat by Pitchblende. 

 By Horace H. Poole *. 



A DESCRIPTION was given in a former paper (Phil 

 Mag. Feb. 1910) of a determination of the rate of 

 evolution of heat by Joachimsthal pitchblende. As the 

 results obtained were considerably greater than was to be 

 expected, further experiments seemed to be desirable. 



The same method and apparatus were again employed, 

 and for a description of them reference must be made to the 

 previous paper. Before insertion in the calorimeter the 

 pitchblende was gentfy heated for several hours on a metal 

 plate. It was then placed while still hot in the calorimeter 

 in which the flexible thermo-junction had already been 

 inserted, and molten paraffin-wax was run in to completely 

 fill up all the interstices. The calorimeter was gently tapped 

 till air-bubbles ceased to rise to the surface. The neck of the 

 calorimeter \\as then closed as before and the whole put 

 aside to cool. The calorimeter contained 525 grams of 

 pitchblende. A week later the calorimeter was buried in 

 ice in the usual way. Another couple was placed in the 

 ice vessel with its junctions at different points in the ice, to 

 indicate what temperature differences might occur in the ice 

 it-elf. 



The readings of the couples are shown on the chart (fig. 1), 

 on which the upper line indicates the temperature of the 

 pitchblende and the lower the differences of temperature 

 between the terminals of the second couple. As the latter 

 was slightly more sensitive than that employed with the 

 pitchblende, the readings have been reduced to the same 

 scale, i. e> scale-divisions indicated by the pitchblende couple. 

 This and the galvanometer were the same as those previously 

 emploved, but the distance from the galvanometer mirror to 

 the scale having been increased from 102 cms. to 107 cms., 



* Communicated, bv the Author. 



