150 HEATING. 



obtain the largest possible extent of contact-surfaces for the air 

 and gases ; which is important, since the short time allowed for 

 the diffusion would otherwise be insufficient, in consequence of 

 the rapid passage of the smoke and gases over the diffusion 

 plates ; e is the spy-hole for ascertaining the state of the smoke. 



FIG. 34 is an apparatus invented by Mr. Jeffreys, of Bristol, as 

 long ago as 1824, for precipitating the lamp-black, metallic 

 vapors, and other sublimated matters from smoke, by washing 

 the latter by means of a stream of water. Where the necessary 

 supply can be secured, this plan is both effectual and economi- 

 cal, and well adapted for situations where the presence of smoke, 

 as well as the impurities produced by it, is an annoyance. 



In the vertical section, B B is the smoke flue. The smoke 

 passing in the direction of the arrows at A, the flue turns down- 

 ward; and at the top of this vertical portion is a cistern E, the 

 perforated bottom of which lets down a constant stream of 

 water, after it is set to work. The shower, in its descent, carries 

 all the smoke and the sublimated matter which has passed from 

 the fire, which runs off at the bottom, F. The flue may then 

 turn upwards, or enter a common chimney ; but little or nothing 

 will pass up it, providing the water be kept constantly running. 

 This apparatus is easily constructed, and is admirably suited for 

 hot-houses situated in the midst of pleasure-grounds, where 

 smoke is unsightly and disagreeable. 



Whether these methods of consuming the gases generated in 

 the furnaces and flues of hot-houses may be considered worthy 

 of general adoption, we cannot tell. It is, nevertheless, pre- 

 sented to the consideration of the ingenious mechanic, not 

 doubting that were the subject fully taken up by energetic fur- 

 nace builders, something good would be the result. That 

 immense quantities of fuel are wasted by imperfect combustion, 

 cannot be doubted, when we see the dense volumes of smoke 

 proceeding from chimneys where much heat is required. 



Professor Brande says, " when air is admitted in front of the 

 furnace, or through or over the fuel, it obviously never can 

 effect those useful purposes, which are at once obtained by 

 admitting it in due proportion to the intensely heated inflamma- 

 ble vapors and gases, or, in other words, to the products of the 



