The Economic Production of Artificial Heat. 405 



"which are a most effective portion of the combustible, and 

 which, if allowed to escape into the atmosphere, are totally 

 wasted. When the combustion is imperfect soot will be formed 

 with a part of the carbon, and, instead of carbonic acid, car- 

 bonic oxide may be evolved. The hydrogen also, in place of 

 being burned, may form hydrocarbons, such as carry vapours, 

 and pass off; or it may escape without having entered into any 

 combination. In all these cases a large amount of the heat 

 which should be derived from the fuel is lost. Smoke is not 

 only a loss to the manufacturer, but an injury and an annoyance 

 to the neighbourhood, by rendering it less healthy and less- 

 agreeable ; hence, the manufacturer is obliged, by Act of Parlia- 

 ment, to " burn his smoke." Burning it, is enough to prevent 

 inconvenience to others; but preventing it, would be more 

 advantageous to himself, since carbonaceous matters combine 

 with oxygen much more readily when they are in the nascent 

 state. Smoke will certainly be consumed, if its constituents- 

 are mixed with oxygen in proper quantities, and at a proper 

 temperature. Atmospheric air contains, by weight, twenty- 

 three per cent, oxygen ; and sixty cubic feet may be considered 

 to afford one pound of it. Hydrogen requires for combustion 

 eight times its weight of oxygen ; and carbon two and two-third 

 times its weight. One pound of hydrogen, therefore, absorbs 

 the oxygen of four hundred and eighty cubic feet of atmos- 

 pheric air ; and one pound of carbon, that of one hundred and 

 sixty cubic feet. The carbon is believed to be capable of giving 

 to the products of combustion a temperature of 4400° Falnv 

 if its combustion is perfect, and some of the heat is not carried 

 away by excessive draught. 



Since the compounds of carbon and hydrogen are found to 

 afford the same amount of heat as their constituents, it is not 

 necessary, in examining the effects which ought to be expected 

 from hydrocarbons, to consider each of them separately ; it is 

 enough if the nature and amount of the elements of which their 

 aggregates consists, are ascertained. Compounds of carbon 

 and hydrogen are usually decomposed by the high temperature,, 

 before they are burned ; then, hydrogen having the greatest 

 affinity for oxygen, first combines with it, liberating the carbon ; 

 the carbon, if there is enough of oxygen, with a sufficiently high 

 temperature, afterwards forms carbonic acid ; but if there is a 

 deficient supply of oxygen, the carbonic acid takes up another 

 atom of carbon, becoming carbonic oxide : in which case as- 

 much heat per pound of carbon, is carried off as would raise 

 10,1 00 lbs. of water one degree Fahr. The blue flame which 

 surrounds the opening, and plays over the fuel, when the door 

 of a locomotive furnace is opened, arises from the extra supply 

 of air changing what was passing off as carbonic oxide into car- 



