﻿208 



Prof. W. Ramsay on the Passage of 



Description of Apparatw 



The apparatus which was em- 

 ployed is represented in the ac- 

 companying woodcut. 



AB is a tube of platinum, the 

 top portion of which, at A, is e 

 of palladium and closed at its 

 upper end. At B the platinum 

 tube is sealed or cemented on to 

 a glass tube C, with a lateral 

 branch, represented in the figure 

 as drawn off and closed. Some- 

 what lower down, the tube is 

 sealed to a capillary D, on which 

 graduations are etched. The 

 tube then widens to a bulb, and 

 is finally connected by thick 

 flexible tubing to a reservoir of 

 mercury E. 



The palladium tube is sur- 

 rounded by a glass tube F, also 

 provided with a lateral exit at 

 Gr, and fitting tightly into a 

 jacket H, which may be heated 

 by boiling the liquid in the 

 bulb I. A gas, passed in at F, would thus surround the 

 palladium tube and escape at Gr ; or if heavier than air, if 

 introduced at G it would escape at F. The palladium cell 

 could be heated to any desired temperature by choosing an 

 appropriate jacketing vapour. The whole apparatus stood in 

 front of a glass mirror-scale, on which the level of the mer- 

 cury at D and E could be read off. It was possible to read 

 to one tenth of a millimetre, but such accuracy of reading 

 was generally unnecessary. 



Description of an Experiment. 



A clip w r as placed on the india-rubber tube joining D and 

 E, and the side-tube C, which at this time was open, was 

 connected with a reservoir of some gas, e. g. of nitrogen, by 

 means of a three-way tap. The palladium tube was pumped 

 empty, and then filled with dry nitrogen ; the operation was 

 repeated ten times, so as to ensure absence of air. The 

 nitrogen was finally allowed to enter the apparatus under 

 slight pressure, and the side-tube C was sealed. The liquid 

 in I was then boiled so as to jacket the tubes F and A, and 



