46 Alll-TKillT STUVE^^. 



draught nii<;lil be so reduced as to give time for the hrnled air, S;.r. (o 

 give out a large portion of their caloric by contact to the upper parts of 

 the stove and pipe, and thus afford it by radiation to the room. But in 

 order that the stove may not smoke, or give ofl' carbonic acid, and other 

 volatile matters, which are injurious to health, into the room the seams 

 must be air-tight. This, then, is the principle of the air-light stove. — 

 The seams are all made so as to fit accurately, the pipe is furnished 

 with a valve, or there is a bonnet or hood in the inside of the stove, ex- 

 tending some distance below the insertion of the pipe, and the door 

 in front, through which the fuel is introduced and by which also the 

 draught is in part regulated, is made to slide closely. The pipe is in- 

 serted at about three inches below the top of the stove, and should de- 

 scend a little towards its entrance in the fire-board, which should also 

 lit closely in the hearth, and have a small valve at the bottom to permit 

 any air, which may be forced down the chimney during stormy weather, 

 to enter the room without passing through the stove so as to prevent 

 smoking. By means of the valve and slide in front, the draught may bo 

 so regulated as to permit no more air to pass through the stove than is 

 necessary to alford the requisite amount of oxygen for combustion, and 

 that little more than the gaseous products, viz : carbonic acid, watery 

 vapor, pyroligneous acid, creosote, and the residua] nitrogen, all greatly 

 cooled by having first given off their heat to the stove by contact, may 

 pass up the flue. So much is their temperature reduced, when the valve 

 is used, that water and pyroligneous acid arc condensed in the pipe be- 

 yond the valve, and hence the necessity of having the pipe to descend 

 towards the fire-board, so as to permit the acid to fall upon the hearth, 

 and not to drop into the room. If the draft is strong, these products 

 will be carried up the chimney. Some think that the valve is unneces- 

 sary, and say that the sliding door may adjust the draught, and that no 

 more air will pass through the pipe than enters in front ; whence many 

 of the recently made air-tight stoves are v/ithout the valve. But it 

 might easily be shown that this reasoning is based upon a philosophical 

 blunder. 



Air-tight stoves are made of various forms and of various degrees of 

 complication. The most simple form, and which may serve as an illus- 

 tration of all tliat it is necessary to state at present, is the oval, willi fiat 

 top and bottom. The latter may be of cast or sheet-iron ; the sides are 

 made by bending a sheet of sheet-iron in oval form, and joining it ac- 

 curately to the top and bottom. As the stove is never permitted to be- 

 come red hot or even near that temperature, the sheet-iron Mill hist, 

 with fair usage, a mun\s life time; tlicie is no dan:/ei of its barniii<: out. 



