220 



42 



To the 

 'pump 11 



*4=^ 



gas. The measurer A, volume 800 ccm., is connected, by means of the hard glass 

 tube C, to the collecting bottle F containing the gas under investigation. 



The gas is cut ofî from the surrounding air by water. The hard glass tube C 

 contains, in three separate compartments, reduced copper, copper oxide and solid 

 hydroxide of potassium. The part containing the copper and the copper oxide 

 is heated, and, by conducting the gas several limes through the tube, possible 

 small remnants of combustible gases, oxygen and carbon dioxide in the gas are 

 destroyed. 



At last all that remains now consisting only of nitrogen and rare, inactive 

 gases, is left behind in the measuring tube A, where its volume is determined. In 

 the meantime I have, by means of the mercury air pump, exhausted the hard 

 glass tube M, containing a mixture ' of 1 part of magnesium powder, 5 parts of 



freshly burned lime (CaO) 

 J and 0.1 part of metallic 



sodium ; the tube is kept 

 at red heat for about two 

 hours, while the mercury 

 pump works constantly to 

 remove the gases evolved by 

 the hot Mg-CaO-Na mixture. 

 When the mixture has been 

 heated so long that the gas 

 evolution has for the most 

 part ceased, the communica- 

 tion to the pump is inter- 

 rupted by closing the stop- 

 cock Ä^, and then the gas in 

 the measurer A is admitted 

 to the absorption tube by opening the stop-cock H. On its way to M the gas is 

 desiccated by phosphorus pentoxide in the tube P. Then the gas is passed through 

 the porous plug R, which is inserted in order to avoid too violent entrance of the 

 gas into the empty tube M. After the absorption of the nitrogen the tube M, while 

 still hot, is emptied by means of the mercury pump, and the remaining gas is 

 collected above mercury in a collecting tube. 



Although the remaining gases obtained as above described consist mainly of 

 rare, inactive gases, yet small amounts of hydrogen and carbon monoxide evolved 

 from the mixture, and perhaps even a trifle of nitrogen, are found. 



The remaining work is to purify the rare, inactive gases from these impurities, 

 and to separate the argon and helium. 



As I had so many gas samples, (nearly 20), the following order of experi- 

 menting with these gas samples turned out to be the most practicable. First, all 

 ' Hkmpel I. e. p. 150. 



Fig. 10. 



