and Detonating Matches. 129 



like the large end of an egg, each about three feet in diameter 

 two feet deep, and "nearly half an inch thick at the bottom, 

 but much thinner above, with a horizontal ledge four inches 

 broad. A pot of good cast iron is capable of distilling 1000 

 tons of sulphur before it is rendered unserviceable, by the action 

 of the brimstone on its substance aided by a strong red heat. 

 The pot is covered in with a sloping roof of masonry, the upper 

 end of which abuts on the masonry of the vaulted dome of con- 

 densation. A large door is formed in the masonry in front of 

 the mouth of the pot through which it is charged and cleared 

 out ; and between the roof -space over the pot, and the cavity 

 of the vault, a large passage is opened. At the back of the pot 

 a stone-step is raised to prevent the sulphur boiling over into 

 the condenser. The vault is about ten feet wide within, and 

 fourteen feet from the bottom up to the middle of the dome, 

 which is perforated, and carries a chimney about twelve feet 

 high, and twelve inches diameter within. 



As the dome is exposed to the expansive force of a strong 

 heat, and to a very considerable pressure of gases and vapours, 

 it must possess great solidity, and is therefore bound with iron 

 straps. Between the still and the contiguous wall of the con- 

 densing chamber, a space must be left for the circulation of 

 air, a precaution found indispensable by experience ; for the 

 contact of the furnaces produces on the wall of the chamber 

 such a heat as to make it crack and form crevices for the liquid 

 sulphur to escape. The sides of the chamber are constructed 

 of solid masonry, forty inches thick, surmounted by a brick 

 dome, covered with a layer of stones. The floor is paved with 

 tiles, and the walls are lined with them up to the springing of 

 the dome ; a square hole being left in one side, furnished with 

 a strong iron door, at which the liquid sulphur is drawn off at 

 proper intervals. In the roof of the vault are two valve-holes, 

 covered with light plates of sheet-iron, which turn freely on 

 hinges at one end, so as to give way readily to any sudden ex- 

 pansion from within, and thus prevent dangerous explosions. 



As the chamber is an oblong square, terminating upwards in 

 an oblong vault, it consists of a parallelepiped below, and a 

 semi-cylinder above, having the following dimensions : 

 VOL. I. OCT. 1830. K 



