800 Mr. F. B. Young on the 



which were suspended also the two reservoirs F and G and 

 the bulb of charcoal H. One end of tube E terminated in 

 the fine capillary tube J, the sealed tip of which was drawn 

 out very thin and bent, so that it might readily be snapped 

 by a gentle pressure. The other end of E communicated 

 with a Topler pump through the mercury trap K, the arms 

 of which were about 90 cm. in height. Between K and the 

 pump was interposed the trap M : this was immersed in 

 liquid air, and by arresting the ether vapour prevented the 

 fouling and consequent loss of efficiency of the pump. Since 

 the experimental tubes were of Jena glass it was necessary 

 to construct the whole of the filling apparatus of the same 

 material. The connexion with the pump was made by means 

 of the mercury-sealed ground joint N. 



In order to free the tubes from moisture and adsorbed air, 

 the apparatus from H to G was covered with asbestos mill- 

 board and heated over a tube furnace. The tubes were 

 evacuated by means of the pump, and the trap K was left 

 open so that they were in communication with the phos- 

 phorus-pentoxide tube attached to the pump. This process 

 was repeated several times. Just before carrying out the 

 filling operations the trap K was closed ; the charcoal bulb 

 was immersed in liquid air for about an hour and was then 

 fused off, so that a Dewar vacuum was created in the tubes. 



The apparatus from K to G was heated well above the 

 boiling-point of ether. The capillary tube J was then intro- 

 duced into the freshly prepared ether, and its tip was broken 

 by pressure against the bottom of the bottle. The first 

 portion of ether which ascended the capillary vaporized, 

 until the internal pressure was equal to that of the atmo- 

 sphere. The reservoir G was then cooled with water, the 

 remainder of the apparatus being kept hot as before. When 

 the desired amount of ether (about 45 c.c.) had collected in 

 G, the flow was checked by immersing G in water at about 

 35° C, and the capillary tube was sealed off near the top. 



The ether in G w^as then frozen with liquid air. The 

 mercury in K, acting as a manometer, still showed a pressure 

 in the tubes of 8'8 cm., this being almost entirely due to the 

 air which had entered in solution. M having been sur- 

 rounded with liquid air, K was opened and the air was 

 pumped off. The ether was then allowed to thaw, and a 

 first portion passed off as vapour through K. The bulk of 

 the ether was condensed in F by means of liquid air ; a little 

 of the remainder was then condensed in the experimental 

 tubes, after which the ether in F w r as allowed to thaw and 

 the first portion of it passed off through K together with the 



