68 



CONSTRUCTION OF RETORTS. 



Fig. 15, 



l 



o 



o 



10 



O 



O 



<--!*--> 



W is a cast-iron plate, 1^ inch thick, on which the fire-door is hinged, 

 serving also to protect the face of the brickwork which it covers. In the 

 centre, and about six inches above the fire-door, a square opening is cast for 

 the admission of an iron spout, when it is required to burn tar. 



X is a pan at the bottom of the ash-pit, for evaporating ammoniacal liquor, 

 and the offensive unsaleable liquid products which cannot be disposed of 

 otherwise. 



Y Y are openings left in the walls N, by which the carbon deposited from 

 the furnace is cleared away. 



I have stated that everything depends upon the heat at which the retorts 

 are worked. It must be obvious that the durability of the distillatory appara- 

 tus greatly depends on the manner in which the heat is applied to effect the 

 decomposition of the coal contained within the retort. If the heat be very 

 intense, the whole vessels are rapidly destroyed ; if it be too languid, the dis- 

 tillation is protracted, the gas is of inferior quality, much fuel, time and 

 labour are wasted to no purpose, and the retorts are speedily deteriorated, as 

 the heat acts upon one part more than upon another. The experiments 

 by which the present plan of heating retorts was arrived at, were many and 



