26 General Notices. 



Art. II. General Notices. 



JI'itty\i Improved Furnace. — When we noticed this furnace, in a for- 

 mer Nunil)er, we were not aware of the extent of the improvement which 

 it is calcuhited to effect ; the inventor having, in a private letter wliich 

 accompanied his conmuniication, chieHy insisted on its power of bnrning 

 waste coal. We have since seen some |)rinted remarks, accompanied by 

 testimonials, which show that the most important advantage of Witty's fur- 

 nace is the hnrning of the smoke, by wiiich a saving of from 20 to .30 per 

 cent of fuel is obtained; and the atmosphere in the neighbourhood of the 

 furnace is not polluted with smoke. It also apjjcars that rather less attend- 

 ance is recjuired than with a common furnace, whether for hot-houses, 

 steam-engines, or dwelling-honses. 



The first princi|)le of excellence in the construction of this improved 

 fiu'nace is the way in which it is supplied with fuel. By the common mode, 

 the moment the door of the fiuMiace is o|)ened, a rush of cold air sweeps 

 throu<rh the flues, or under the boiler, carrying off nnich heat. Cold, and 

 perhaps moist, coal is then thrown on the very centre of the fire, which not 

 onlv reduces the heat, but occasions a quantity of dense smoke to be emit- 

 ted from the chimney; and this smoke, when once formeil, cannot be 

 burned except at a temi)erature (.3000° Fahrenheit) that will melt iron. 

 This temperature would, of course, require an amazing exjiense of fuel. 

 The mixture of about one twelfth of atmospheric air with carburetted 

 hvdrogen, of which smoke of coal is chiefly composed, produces com- 

 bustion at a high temperature. By throwing on a fire unprepared coal, not 

 only this inflammable gas (carburetted hydrogen) is generateil, but also 

 nitrogen, carbonic aciil gas, and other non-inflannnable gases; anil it has been 

 proved, that when smoke contains one sixth part of nitrogen, or one sixth 

 of carbonic acid gas, it will not inflame. Hence the difficulty of consnn>ing 

 smoke. In order to overcome this difficulty, Mr. Witty divides the con- 

 sumption of coal into two distinct processes: viz. carbonisation, by which the 

 coals are thorouizhly dried, and freed from their watery anil gaseous matter; 

 and combustion, in which the carbonised coal, or col-^e, is consumeil along 

 with the watery and gaseous matter wliich is distilled from that portion of 

 coal which is undergoing carbonisation. By these two processes, the maxi- 

 nunn of heat is obtained from any given (juantity of fuel; and this without 

 one particle of smoke. By Mr. Witty's plan, the atmospheric air is no- 

 where admitted but through the coke fire, and this inflames all the gaseous 

 matter, as it is evolved from the coal undergoing distillation. 



It is important here to observe, that, us a very high temperature is 

 essentiallv necessary for the consumption of smoke, that object can never 

 be effected under a boiler in which water is not raised nuich beyond 

 the boiling point. Now, the great superiority of Mr. Witty's plan is, 

 that the smoke is consumed before the flame anil the heat come in 

 contact with the l)oiler. We are the more anxious to direct attention 

 to this, because, in heating by hot water, it will be found necessary to place 

 the boiler not inuuediately t)ver the fuel, but rather over the connnence- 

 ment of the flue; or, at whatever may be the point where all the gaseous 

 matters are consumed. It will be seen in our advertising sheet that this 

 furnace has been erected in several gardens, and that it has given the 

 highest satisfaction. Mr. Miller of the Bristol Nursery has had two fur- 

 naces put n|) to his steam boilers, which, he says, effectually consume the 

 smoke, and produce a greater (piantity of heat with less fuel. Mr. U. Mil- 

 ler, the very intelligent gardener at Alton Towers, who has had the ma- 

 nagement of several of the hot-houses and conservatories there, strongly 

 reconunends it as being |)referal)le to any other furnace that he has seen, 

 producing a great heat generally diffused, with less coal and no smoke. 

 There is one of Wittv's furnaces erected at Lee's Nurserx, Hammer- 



