502 Mercury -still for the Rapid Distillation of Mercury. 



the beautiful new form of apparatus, devised by Messrs. 

 Dunstan and Dymond, for the purification of small quantities 

 of mercury (supra, p. 367). In the former of these instru- 

 ments, some portion of the mercury-vapour condenses on 

 the surface of the bulb and then falls back to the mass 

 of mercury from which it has just been separated. The 

 mercury-still which is described in the following lines has 

 been constructed with a view to obtain a more rapid yield of 

 pure mercury than stills of this class have hitherto been 

 capable of producing. The yield of mercury from the new 

 form of still is about four times as great as that from one of 

 the old pattern, the consumption of gas in each case being the 

 same. The construction and method of using the still are as 

 follows : — B K is a bulb and tube about 34 inches long, sup- 

 ported on a stand not shown ; the bulb has a ring-shaped 

 channel, C C, round its upper end ; into this channel a piece 

 of " Sprengel" tube, D, is fused. This is furnished with two 



K 



E 



m5 



1 



taps of glass, E and F ; E is in connexion with a water-jet 

 pump, F is terminated with a piece of bent tube. A is a 

 cistern for holding the mercury which is to be distilled. H is 

 a ring of gas-jets. 



