610 PROCEEDINGS OF THE AMERICAN ACADEMY. 



(b) Same. Temperature, 260°. Gas evolved, 13.2 c.c. 



Composition : 



Carbon dioxide 9.2 % 



Oxygen 4.7 " 



Carbon monoxide 6.6 " 



Hydrogen 51.9 " 



Nitrogen (remainder) .... 29.0 " 



101.4 " 



The analytical methods were as follows : — Carbon dioxide by ab- 

 sorption in caustic potash ; oxygen by alkaline pyrogallate ; carbon 

 monoxide by copper ammonium chloride, and from the explosion re- 

 sults : hydrogen by explosion with pure oxygen ; nitrogen as remainder, 

 subject to check of more minute analyses of the rare gases. Unsaturated 

 hydrocarbons were tested for by bromine water. Hydrocarbons of the 

 marsh-gas series would have shown themselves in the combustion results 

 if present. 



The test for the gases of the helium group was made on the whole 

 amount of gas from about 10 kilos of fluorite. This volume of gas (about 

 7 liters) was freed from carbon dioxide by collecting it over caustic soda 

 solution, and then put through the regular purification process as given 

 by Travers 44 , finally passing over metallic calcium in a series of com- 

 bustion furnaces. The residue was then subjected to the action of the 

 spark for some time, and the very small quantity of gas remaining was 

 sent on into the spectrum tube through the second pump, which had pre- 

 viously been used to obtain a vacuum in the Geissler tube. The volume 

 of gas remaining after purification was somewhat less than 2 c.c, and 

 this showed only lines of nitrogen and hydrogen, without any indication 

 of the gases of the helium group. A further purification of this residue 

 resulted in its practical disappearance. It was expected that argon 

 would be present, but no lines of this element were observed. A care- 

 ful test for helium in fluorite has been made by J. Thomsen with 

 negative results. 45 



The Liquid Distillate. 



This consists practically entirely of water, although it is brown in 

 color in every case and has a very strong " empyreumatic " odor. It 

 boils at 100° exactly, and gives nothing but water on fractionation. 



44 The Experimental Study of Gases (1901). 



45 Ztsch. fur plvys. Chetn., 25, 114 (1898). 



