Constituents of certain Mineral Substances and Waters. 443. 



indication of the presence of any new element has been obtained, nor 

 has any abnormality been observed in the spectrum of any of the 

 examined. 



Fm. 1. 



Method of Examination of the Mineral Substance. 



The mineral was ground to fine powder in an agate mortar, and 

 then mixed with about twice its weight of acid potassium sulphate. 

 This mixture was placed in a hard glass tube, which was connected 

 with a Topler pump, and, after exhaustion, heated to a red heat by 

 means of a large Bunsen burner. The gases evolved were pumped 

 off and collected over mercury in a tube containing a little caustic 

 potash solution. In some instances, however, the mineral was heated 

 alone ; the same result was obtained, but the evolution of gas takes 

 place rather more slowly. In order to diminish any chance of leak- 

 age of air into the apparatus, the hard glass tube was connected with 

 the pump in the manner shown in fig. 1. The tube was drawn 

 out to a neck at the point A. A piece of thick- walled rubber tube 

 was fitted over the end of the tube B connected with the pump, and 

 it was then forced tightly into the neck of the hard glass tube. By 

 pouring a little mercury into the cup C the joint could be made 

 absolutely air-tight. 



Examination of Minerals and Rocks. 



Several samples of fergusonite, monazite, and samarskite were 

 first examined, and were found to give quantities of helium up to 

 1*5 c.c. per gram. 



Columbite (a variety of tantalite), an isomorphous mixture of 

 niobate and tantalate of iron and manganese, gave 1*3 c.c. of gas con- 

 sisting chiefly of helium. 



Pitchblende, containing zirconium, obtained by Dr. Hillebrand from 

 Colorado, gave 0'36 c.c. of gas per gram, of which 0*3 c.c. was 

 helium. Another sample gave 0'27 c.c. of helium per gram. 



