514 



be drawn under pressure tlirougli carbon, cooled with liquid air, 

 by means of the compressor with mercury-piston Q (compare Comni. 

 54 Jan. 1900) and returned to Ri or to tiie gasometer in purified 

 condition. The carbon is contained in Z^ (which is cooled) and Z, 

 (a reserve tube), copper hardsoldered receivers wliich may be exhausted 

 by the merciiry-airpump {vac in the figure) at red heat. The remaining 

 gas is transferred by the air-pump to a gasholder for im|)ure neon. 

 The wa_y of using the cocks and the obje(;t of the safety-tube T, 

 which in case of need takes back the gas to the gasholder for impure 

 neon, as also of stop-cock 2 will be clear without special elucidation. 



The cryostat is filled witli the pure neon from the gasometer by 

 stop-cock 4 through a drying-tube /J, immersed in liquid ain from 

 here it. flows with stop-cock 6 open by c\ (comp. fig 1) into the 

 liquefactor, from which as explained in § 2 the liquefied neon flows 

 down into the cryostat. The vaporized neon escapes through «S'g to the 

 gasomelei'S (r, and (t,. When the cryostat is filled the small cock 

 Eak, and slop-cock 6 are closed. The neon which might then evaporate 

 in the liquefactor may escape through stop-cock 8 into the gasholder 

 for impure neon. 



As usual the cryostat has attached to it a safety-tube X ; the gas 

 which might escape through it is caught in the small safety-gaso- 

 meter Gv. When the small cock E^k^ is closed, the temperature of 

 the bath may be regulated in the usual manner according to the 

 indication of manometer J7 and with the aid of the differential- 

 manometer shown beside it (comp. Coinm. 83, Dec. 1902) by opening 

 7 more or less. 



The apparatus itself and the connections may be evacuated by 

 manipulating stop-cocks 10 and 11. The exhaustion is performed 

 before the experiment to make sure of' a proper operation of the 

 cryostat and again after the completion of the experiment to transfer 

 the gas contained in the apparatus back to the gasholder for impure 

 neon. Before proceeding to the latter operation the liquid neon is 

 transferred to the gasometers (r, and G^, either by allowing the 

 liquid to evaporate with the cryostat connected to the gasometers, 

 or by (lowing the liquid to the gasometers by pressure through the 

 syphontube h, allowing the liquid neon to evaporate in the passages 

 on its way to the gasometers, or finally by pumping the liquid ont 

 and forcing it into the gasometers with the Siemens-pump TF. The 

 gas which is left in the Siemens-pump is ti'ansferred by the mercury- 

 pump to the gasholder for impure neon with all the other gas 

 remaining in the whole apparatus and connections at the end of 

 the experiment as already mentioned. 



