at Apothecaries' Hall. 201 



There are also a series of furnaces built against the sides of the 

 main chimney, and communicating directly with it by flues of 

 their own, which, as well as the common openings by which they 

 enter the chimney, are supplied with effectual registers, so that 

 when not in use they may be perfectly closed. Of these furnaces, 

 four are chiefly employed for various sublimations, and fusions ; 

 four are retort pots ; the third side of the chimney is occupied by 

 a powerful wind furnace ; and the fourth by a furnace for the sub- 

 limation of calomel. In this laboratory there is, moreover, a very 

 copious supply of water, both hot and cold ; and an engine-hose 

 and pipe is always attached to the water main, in case of accident 

 by fire, as well as for the purpose of cleansing the pavement. 

 Beneath the building are extensive vaults for fuel, with which there 

 is a direct communication by steps descending in one of the angles 

 of the laboratory. 



The still-house contains six stills of various dimensions and con- 

 structions, twelve pans, or boilers, and a drying stove, all of which 

 are exclusively heated by steam, supplied from an eight hundred 

 gallon copper boiler, placed in an annexed building, below the 

 level of the still-house ; and the flue of which, passing under the 

 pavement of the laboratories, enters the main chimney already 

 described. 



The boiler is calculated to supply steam under a pressure of an 

 atmosphere and a half, and is fed with hot water by a forcing 

 pump kept in constant operation by the steam-engine. It is pro- 

 perly fitted with valves, and pressure and water gauges. 



The main steam-pipe, after ascending from the boiler, sends off 

 descending branches which ramify under the pavement of the still- 

 house, in channels of brick-work, covered by cast-iron plates. 

 These send off a steam-pipe, fitted with a register cock, to each 

 still and boiler, from which there passes off an eduction or con- 

 densed water-pipe, entering the condensed water main, the rami- 

 fications of which accompany the steam main, and deliver their 

 contents into a cistern, whence the boiler is supplied with hot 

 water. A large branch of the steam-pipe circulates in five con- 

 volutions at the bottom of the drying stove, so as to heat a cur- 



