APPENDIX II TO CHAPTER V 153 



APPENDIX II TO CHAPTER V 



APPARATUS used by Rayleigh and Ramsay for isolating argon 

 on a large scale from the air. 



FIGURE 1 MAGNESIUM METHOD. 



A is the circulator. It consists of a sort of Sprengel's pump (a), 

 to which a supply of mercury is admitted from a small reservoir 

 (6). This mercury is delivered into a gas-separator (c), and 

 the mercury overflows into the reservoir (d). When its level 

 rises so that it blocks the tube (/) it ascends in pellets or pistons 

 into (e), a reservoir which is connected through (g) with a water- 

 pump. The mercury falls into (6) and again passes down the 

 Sprengel tube (a). No attention is therefore required, for the 

 apparatus works quite automatically. 



The gas is drawn from the gasholder B, and passes through a 

 tube C, which is heated to redness by a long flame burner and 

 which contains in one half metallic copper and in the other half 

 copper oxide. This precaution is taken in order to remove any 

 oxygen which may possibly be present (in the atmospheric 

 " nitrogen " used), and also any hydrogen or hydrocarbon. In 

 practice it was never found that the copper became oxidised, 

 or the oxide reduced. The gas next traversed a drying tube D, 

 the anterior portion containing ignited soda lime and the posterior 

 portion phosphoric anhydride. From this it passed to a reser- 

 voir D', from which it could be transferred, when all absorption 

 had ceased, into the small gasholder. It then passed through E, 

 a piece of combustion-tube, drawn out at both ends, filled with 

 magnesium turnings and heated by a long flame burner to red- 

 ness. Passing through a small bulb, provided with electrodes, 

 it again entered the fall-tube. 



After the magnesium tube E had done its work, the stopcocks 

 were all closed, and the gas was turned down, so that the burners 



