202 On the Chemical Establishments, fyc. 



rent of air which is made to pass through it ; and another branch, 

 rising perpendicularly through the pavement, is properly fitted 

 with cocks and screws for the occasional attachment of leaden or 

 other pipes, for boiling down liquids in moveable pans and vessels. 



In this building, one of the stills is of a distinct construction, 

 and heated by high pressure steam, supplied from the boiler 

 already mentioned in the description ©f the laboratory. Another 

 still, together with its condensing pipe, is composed entirely of 

 earthenware. The former is chiefly used for the first distillation 

 of sulphuric ether, and the latter for that of spirit of nitric ether. 

 The stills and vessels are generally heated by the circulation of 

 steam upon their exterior, but sometimes serpentine pipes travers- 

 ing the liquor are employed. 



In the still-house all spirits and waters are distilled ; extracts 

 and plasters are prepared ; and all operations are carried on 

 which involve risk by fire, or in which damage is likely to occur 

 from excess of heat. 



The Magnesia-room contains proper vats and boilers for the pro- 

 duction and evaporation of saline solutions ; the apparatus for the 

 precipitation of carbonate of magnesia ; and a series of vessels 

 for saturating alkalies with carbonic acid. 



In the above outline it has been intended to shew that no labour 

 or expense has been spared to render the chemical laboratories 

 complete, and that all the important modern improvements in 

 their construction have been adopted upon an extensive scale, 

 rather than to enter into any particulars respecting the arrange- 

 ment and dimensions of the vessels, furnaces and apparatus which 

 they contain. These details will be found in the description of 

 the annexed Plate representing the ground plan of the laboratories. 

 —See Plate. 



