Quantity of Radium in Bocks and Minerals, fyc. 145 



view may be obtained of the platinum boat during the progress 

 of an experiment. To permit of this the fire-clay plug at 

 this end is perforated centrally. A Lateral and smaller 

 tube, soldered to this wider tube, conveys the escaping gases 

 to the soda-lime tubes and collecting-bag of rubber. The 

 other stopper carries a tube which is kept closed till the con- 

 clusion of the experiment. Then when the transfer of the gas 

 to the electroscope is completed and the rubber bag is quite 

 empty, this tube is opened and the contents of the furnace 

 washed out by a current of air into the electroscope. 



In order to secure a better wash-out of the soda-lime tubes 

 the connexions are so arranged that the contents of the 

 rubber bao- are first drawn back through the soda-lime tubes 

 on their way to the electroscope, and when the bag is empty 

 the wash-out air-current passing through the tube-furnace 

 traverses the absorption-tubes in the other direction before 

 admission to the electroscope. The diameter of the fusion-tube 

 being 3*3 cm., its content of gas may be taken by an electro- 

 scope of between 600 and 700 c.c. capacity, and leave room 

 in the electroscope for a sufficient wash-out of the furnace. 



With the use of a metal inner tube the temperature reached 

 in this furnace is hardly so high as that attained in the first 

 described furnace. The current prescribed by the makers 

 must not be exceeded. This gives in the inner tube a bright 

 orange-yellow heat, which, as will presently be seen, seems 

 nearly or quite as effective as the higher temperatures. The 

 details of an experiment need not be described, thoy are 

 essentially the same as in the case of the other furnace. 



Working with this furnace Mr. Fletcher kindly made for 

 me the following determinations upon samples of granite 



Locality. 



Wt. of Rock, 

 grms. 



Wt.ofCarbs.. 

 grrns. 



Kesult by 

 Solution. 



Kesult by 

 Fusion. 



Killmey Hill 



Gleucullen 



6 

 6 

 G 

 6 

 6 

 6 

 « 



24 

 24 

 24 

 24 

 24 

 24 

 24 

 Means ... 



1-76 x 10 " 12 

 1-2 „ 

 041 ,. 

 2 -OS 



102 „ 



241 „ 



„ „ 



1-48 „ 



2-9X10" 12 



If „ 



10 „ 

 22 „ 



IS „ 

 30 „ 

 3-0 „ 



213 „ 



Glenmalure 



Ballyellin 



Aughrim 



Blackstairs lit — ... 





Phil. Mag. S. 



6. Vol. 22. 



No. 127. J 



T ubj 1911. 



L 



