USED IN CHEMISTRY. 9 



we wish to separate two fluids of different degrees 

 of volatility, and to preserve the most volatile, or 

 both of them. The substance to be subjected to 

 distillation is put into some vessel that will resist 

 the action of heat, called a retort, an alembic, or a 

 still, having a beak or neck projecting from it, to 

 which is attached another vessel, to receive the 

 fluid that rises first, which is called the recipient, 

 or receiver. The vessel that contains the liquor to 

 be distilled is placed upon the fire, or in a sand- 

 bath, or over a lamp : the heat causes the most 

 volatile fluid to rise in the form of vapour, and to 

 pass into the receiver, where it is again condensed 

 by cold. This condensation is sometimes as- 

 sisted by making the vapour pass through a tube 

 which is immersed in a vessel containing cold 

 water. 



A (Plate 1. fig. 1.), represents a retort used for 

 distillation. It is a vessel, either of glass or baked 

 earth, for containing the liquid to be distilled. 

 When it has a small neck, a, with a stopple fitted 

 to it, for introducing the materials through, it is 

 called a tubulated retort. B is the receiver for con- 

 densing the vapour which is raised, and into which 

 the neck of the retort is inserted. The joining, b, 

 is made air-tight by means of some substance ap- 

 plied to it, called a lute. Various methods are 

 used for supporting both the retort and receiver, 

 according to the degree of heat employed in the 

 process, and several other circumstances. 



When great heat is employed, earthen retorts 

 are used, which are placed on or in the fire. When 

 a less heat is wanted, glass retorts are generally 

 employed, which must not not be placed imme- 

 diately on the fire, unless they are coated over 

 with a composition of clay and sand, which is 



