Burning Gas for supply itig Heat. 293 



heated in a flame of the mixed gases, where there is no free 

 oxygen to attack its surface, it may be made and kept red 

 hot without any injury to its finest edge ; it will be discolour- 

 ed, but without losing much of its polish. The artist has also 

 the advantage of a distinct view of the article while it is being 

 heated, and the power of withdrawing it from the flame the 

 moment it has acquired the proper colour which, in the hard- 

 ening of cast-steel cutting tools, is of great importance. 



Many attempts have been made to apply carburetted hydro- 

 gen and piu;e hydrogen gases to the purposes of warming build- 

 ings, and various forms of stoves have been proposed, on the 

 understanding, it would appear, that, by applying the flame 

 of the gas to metallic bodies, an increased degree of heat would 

 be communicated by them to the atmosphere around. A little 

 consideration will shew, that however the distribution of heat 

 may be modified by such contrivances, there can be no in- 

 crease of the heating power ; and that when a certain measure 

 of gas is fairly burned, the heat evolved into the apartment 

 will be the same whether the flame be disposed as a light, or 

 made to play against metallic plates or other combinations of 

 apparatus. In all cases where the products of the combustion 

 are allowed to mix with the atmosphere of the apartment, 

 without provision being made for carrying them ofi' by venti- 

 lation, the effects of such processes must be more or less dele- 

 terious to health, according to the proportion these products 

 bear to the mass of air they mix in. On the whole, it may be 

 assumed, that this mode of heating apartments is the most ex- 

 pensive, the least efficient, and, excepting that by Joyce's char- 

 coal stove, the most insalubrious that can be resorted to. 



On the best Method of Burning Gas for the purpose of Illu- 

 mination. By Sir John Robison, K. H., Sec. R. S. E., 

 M.S. A.* 



The theoretical principles on which carburetted hydrogen 

 gas may be used with the best advantage, for the purpose of 



* Read before the Society of Arts for Scotland, 27th JIarcli 1839. The 

 Bpccial thanks of the Society awaixled, 18th December 1839. 



