84 Prof. W. Ramsay. Helium, a Gaseous [May 2, 



Taken 24'0 c.c. 



After addition of oxygen 34'0 ,, 



After sparking 32'5 



It appears therefore that this gas contains some, but not much 

 nitrogen, and practically no free hydrogen. It must be concluded 

 that the hydrogen obtained in such large quantity from the crude 

 felspathic mineral (see below) must have been derived from some free 

 metal which it contained. 



An attempt was also made to extract gas from Cornish pitchblende, 

 a large sample of which I owe to the kindness of Mr. Kitto. It is 

 decomposed by acid very slowly, and it also evolves gas when heated 

 in vacuo, but in exceedingly small quantity. From 50 grams only a 

 few cubic centimetres are evolved. 



Similar results were obtained with a sample of pitchblende of 

 unknown origin which I happened to possess. The amount of gas 

 obtained was quite insignificant. 



4. Density of various Samples of Gas. 



It has been stated in the preliminary note already referred to, that 

 the spectrum of the gas extracted from cleveite is characterised by a 

 brilliant yellow line, which, according to Mr. Crookes' measurement, 

 has the wave-length 587*49 millionths of a millimetre, and is identical 

 with the line D 3 , to which Mr. Lockyer many years ago gave the 

 name " helium," from its occurrence in the spectrum of the sun's 

 chromosphere. As the line D 3 is observed high in the chromo- 

 sphere, it has been inferred that the density of the gas should be 

 very low. Special interest therefore attached to the determination of 

 this important property. 



The gas used for the first experiment was the crude gas from the 

 felspathic rock containing cleveite. 



About 300 c.c. confined over strong caustic potash solution, which 

 has been well boiled to expel all air, were used. The globe, which 

 was the same one that served for weighing argon, had a capacity of 

 162*843 c.c. The data are as follow : 



Volume of gas 162'843 c.c. 



Pressure (corrected) 756'5 mm. 



Temperature 17'0 



Weight 0-0212 gram. 



Weight of 1 litre at and 760 mm. 0'1389 

 Density (O = 16) T555 



This gas, as will be afterwards explained, contained free hydrogen. 

 In order to purify it from this constituent, it was passed from one 

 gas-holder to another several times over red-hot copper oxide. The 



