1904.] certain Minerals and Mineral Waters. 197 



Now the saline residue gives about ± part of the quantity of 

 emanation that samarskite gives. Let us assume that the latter 

 contains one-millionth part of radium, which is, I think, an outside 

 estimate. At that rate, the annual delivery of radium by the spring 

 amounts to about one-third gramme. The volume of gas which the 

 spring delivered is about 100 cubic feet per day."* About l0 1 00 part of 

 this is helium, so that about 3 litres of helium is given off daily, or 

 about 1,000 litres per annum. The proportion of helium to radium 

 thus indicated is of the same order as in the radio-active minerals, 

 though somewhat larger. This is in accordance with the view that 

 the spring draws its supplies from the disintegration of such minerals. 



In obtaining the various materials from the Bath springs, I have had 

 the great advantage of Mr. Sydenham's help. His knowledge of 

 everything connected with the springs has been of great assistance. 



In addition to the Bath and Buxton waters I have examined several 

 others. A sample of the Cheltenham saline water, and also a deposit 

 left in the pipes, was kindly sent me by Mr. G. Ballinger. But no 

 emanation could be obtained, either from the dissolved salts or from 

 the deposit. The boiler crust from a domestic hot-water pipe, Terling,. 

 Essex, was examined, but the result was again negative. 



* Williamson ' B.A Kerorts,' 1865, p. 380. 



VOL LXXIII, 



