8^ 



where its combustion may be expected to take place, but this con- 

 tributes nothing to economy of I'uel, it rather produces an opposite 

 effect, as the air admitted through the sht will unquestionably be 

 heated at the expence of the boiler. 



This will demand more fuel than would have been necessary if 

 the furnace were perfectly closed, and the encreased expenditure is 

 probably the reason why fumivores are not universally used ; but 

 surely the improvement of these contrivances is an object of national 

 importance ; and as I have pointed out the probable cause of disap- 

 pointment in Mr. Roberton's apparatus, it is to be hoped that ma- 

 nufacturers will turn their attention to the subject. I had in con- 

 junction with Mr. Kiernan tried many experiments to this effect 

 even before I knew that any thing liad been done by others, and 

 we observed this defect of which I have spoken, the remedy was 

 obvious and on trial it succeeded, the smoke must not be permitted 

 to come into contact with the boiler until it is enflamed, and there- 

 fore the fire-place must be detached, and we must resign the caloric 

 which is radiated from the fire, employing only the current of flame. 

 Our experiments were necessarily made on a small scale, they how- 

 ever were completely successful; and the destruction of the smoke was 

 attended with a great increase of heat. In a reverberatory whose bad 

 performance had excited us to these experiments, this was remarkable, 

 it had failed to fuse brass in its original condition, and with (r) 

 nearly the same quantity of coal it became capable of fusing cast 

 iron and vitrifying Stourbridge clay. A sand-bath, of which I an- 

 nex a plan to explain in what our method consists, had a grate 9 

 inches sqiiare, the flame was directed round two sandpots 18 inches 



(r) More coal was burned on account of the increased draught. 



