On Smelting of Lead. 18gi 



*' When it is said that the sulphur is consumed by the 

 flame of the furnace as soon as it is separated from the orCj 

 the reader will please to recollect that sulphur consists of 

 two parts, — of an inflammable part, by which it is rendered 

 combustible, — of an acid part, which is set at liberty, in 

 the form of vapour, during the burning of the sulphur. 

 Now this acid, though it may be driven out of the furnace 

 in the form of vapour, yet is incapable of being therebv 

 decomposed ; it still continues to be an acid ; and, could 

 the vapour be condensed, might answer all the same pur- 

 poses as the acid of vitriol ; since all the acid of vitriol, 

 now used in commerce, is actually procured from the 

 burning of sulphur. That the fact, with respect to the acid 

 not being decomposed, is as I have stated it, may be readilv 

 proved. The smoke which issues out of the chimney for 

 some hours after each fresh charge of ore, has a suffocatinc 

 smell, perfectly resembling the smell of burning brimstone" 

 and if a wet cloth, or a wet hand, be held in it for a very 

 short space of time, and afterwards applied to the tongue, 

 a strong acid will be sensibly perceived. Various methods 

 may be invented for condensing this acid vapour, and, pro- 

 bably, more commodious than the following one, which, 

 however, I will just take the liberty of mentioning, as, if it 

 should not succeed, the trial will be attended with very lit- 

 tle expense. 



" Supposing then an horizontal chimney to be built, let 

 the end furthest from the fire be turned up by a tube of 

 earthenware, or otherwise^ so that the sulphureous acid 

 may issue out in a direction parallel to Ihe flue of the chim- 

 ney, and at the distance of about a foot and a half above it. 

 Let a number of large globular v^essels be made of either 

 glass or lead; each of these globes must have two necks, 

 so as to be capable of being inserted into one another; let 

 these vessels be placed on the flue of the chimney, the neck 

 of the first being inserted into the tube through which we 

 have supposed the sulphureous acid to issue, and the neck 

 of the last being left open, for fear of injuring the draught 

 of the furnace. Let each of these globular vessels contain 

 a small quantity of water; then it is conceived that the 

 heat of the flue will rriise the water into a vapour, and that 

 this watery vapour will be the means of condensing sul- 

 phureous acid vapour, if not wholly, at least in such a de- 

 gree as may render the undertaking profitable. When the 

 .sulphur is all consumed, the draught of the furnace may be 

 suftered to have its oidinary exit at the end of the horizon- 

 tal chimney, by a vtry slight coiiliivauce of a nioveable 



damper. 



