different kinds of Coal-gas Burners, S^c, 233 



draw the conclusion that the heat evolved when the gas is con- 

 sumed on gauze, is the same as when it is burned in any other 

 way ; and, consequently, when used as a source of heat, it is, 

 generally speaking, of little consequence how it is consumed, 

 in so far as regards the heat evolved ; the evolution depending, 

 not on the manner in which the gas is burned, but on the 

 quantity^ provided of course that the combustion is complete ; 

 and it is of the utmost consequence to attend to this, for when 

 any of it escapes combustion, not only is there a loss of heat, 

 but there is also an offensive smell, more especially when gauze 

 is used. 



With respect to the method of combustion to be preferred, 

 much must depend on the object to be heated. When it is 

 small, as a glass flask or a pot, and it is wished to heat it 

 quickly, I prefer the argand with a copper chimney ; for larger 

 objects, the rose jets or wire-gauze may be used. The former 

 of these may be of different sizes, according to circumstances, 

 but the apertures must always be at such a distance from each 

 other, that, when the gas is inflamed, the flames shall not run 

 together, so as to cause smoke. In using these burners, the 

 nearer the flames are to the object to be heated the better, 

 but they must not come in contact with it, because then there 

 is smoke. With regard to the gauze, air must be freely sup- 

 pHed from below, and the gauze ought not to be near the ob- 

 ject, otherwise the gas is not all consumed. 



Though gas, when consumed by these means, gives out heat 

 in proportion to the consumption, much must depend on the 

 form of vessel employed, as, in one case, more of the heat may 

 be successfully applied than in another. When, for instance, 

 the burner, whether a common burner or gauze, is placed be- 

 low a common pot or a glass flask, much of the heat is lost by 

 radiation, and also by the current of warm air, which, though 

 striking the sides of the vessel, is carried off without having 

 time to communicate its heat to it. Hence, if we employ a 

 vessel so formed as to surround the flame, much of the heat 

 that would otherwise be lost is saved. Thus, when a 24-holed 

 argand was placed under a pot, with the chimney half an inch 

 from the bottom of the pot, by half a foot of gas consumed in 

 seven minutes, water was raised from 45 to 80, giving a gain 



