328 



Prof. W. Ramsey. Helium, a Gaseous [Mar. 19. 



spectrum of tliis gas still showed a trace of hydrogen, and, what was 

 worse, some signs of nitrogen. Its density was, however, deter- 

 mined. 



Temperature, 14*28° ; pressure, 777*4 mm. 



Weight of 162-843 c.c. of gas 02994 gram. 



Weight of 1 litre at 0° and 760 mm 01892 



Density, compared with = 16 2*117 ,, 



Further circulation for a day over magnesium removed this nitro- 

 gen, and hydrogen also disappeared, so that it was not visible speetro- 

 scopically. A final determination of density was made. 



Temperature, 14*95°; pressure, 770*7 mm. 



Weight of 162-843 c.c. of gas 02957 gram. 



Weight of 1 litre at 0° and 760 mm 0*1889 „ 



Density compared with = 16 2*114 ,, 



These results will be discussed later. 



§ 7. Gas was prepared from 500 grams of fergusonite. This time 

 no drying tubes or tubes filled with soda-lime were interposed between 

 the tube containing the mineral and the pump. There was a vacuum 

 tube, as usual, on the way to the pump, into which samples of the 

 gas could be introduced and examined at any desired pressure. The 

 object of this was to make sure that no unknown gas was being 

 rejected owing to its absorption by soda or anhydride. The result 

 proved the precaution to have been quite unnecessary. Every line 

 visible was identified as belonging to hydrogen, carbon, carbon 

 dioxide, the oxygen of water vapour, or helium. It may be taken as 

 certain that no gas capable of absorption is evolved from this mineral, 

 and it is exceedingly improbable that any gas has been overlooked 

 w hich finds its source in other minerals. 



The gas from fergusonite was treated with caustic soda to remove 

 carbon dioxide, and circulated over the usual absorbent till the 

 hydrogen spectrum disappeared, and its density was determined. 



Fergusonite gas. 



Temperature, 14*05°; pressure. 755*8 mm. 



Weight of 162*843 c.c. of gas 0*02955 gram. 



Weight of 1 litre gas at 0° and 760 mm 0*1919 



Density compared with O = 16 2*147 ,, 



A second determination was made with another sample which had 

 been separately purified. The weighing globe was in the meantime 

 cleaned and dri?d, and its stopcock re-greased. There had been 

 reason to suspect a slight leakage. 



