WARMING AND VENTILATING OCCUPIED BUILDINGS. 



301 



their sides. They are usually so badly made that they should not be used 

 in dwellings. According to some recent direct and careful experiments* 

 made in 1867 by H. Deville and Troost, cast iron, at a red heat, readily 

 allows the passage of gas, especially hydrogen and carbonic acid, which 

 explains the very injurious and even poisonous effects produced by the 

 use of stoves in the rooms of a dwelling. At best, they should only be 

 used for warming passages and such rooms in the house as are frequently 

 opened, or in which the air may be easily changed. 



Stoves made of porcelain or sheet-iron are far preferable, and are not 

 subject to the same defects, but they do not secure a more rapid change 

 of air. 



It is proper to add, however, that, for some years back, stove-founders 

 have been striving to improve cast-iron 

 stoves, the imperfections of which, though 

 not at first so well known, were still per- 

 ceived. Stoves are often made at present 

 so that after the fire is started, the opening 

 of movable doors or the removal of blowers 

 converts them into grates detached from 

 the wall, and able, with sufficiently large 

 chimneys, to produce ventilation similar 

 to that of ordinary fire-places. In addi- 

 tion to these plans, many forms of which 

 are made in foundries,if a fire-brick lining, 

 which is easily renewed, be placed in the 

 stoves, the excessive and sudden over- 

 heating of the iron and the rapid destruc- 

 tion of the metal will be prevented, and 

 the unpleasant effects resulting from the 

 use of cast-iron stoves much diminished. 



Similar arrangements might also be in- 

 troduced into those little furnaces used at 

 the same time for warming the room and 

 for cooking; as well as in the construction 

 ©f hot-air furnaces. 



18. Stoves with circulation of hot air. — When the air which passes 

 through the pipes and out through the hot air openings is taken from 

 the room itself, the previously-mentioned unpleasant effects continue, 

 and, besides, since the air from these openings is at a temperature often 

 above 212*^, they injuriously affect the people near them, and are un- 

 healthful. 



If the hot-air passages and the draught be supplied from the external 

 cold air, a part of the heat given out by the fuel being employed to 

 warm this air, the heating- effect of this apparatus will be slightly 

 increased, because the escaping gases will be less warm ; but it' will not 



* Comptes rendus del' Acad6mie des sciences, 13 jauyier 1868. 



Tlsm. 



