DOMESTIC FIREPLACE CONSTRUCTION. 233 



as is the case in ninety-nine times out of a hundred, they are shameful 

 waste, and more than waste, for they entail a great cost for their re- 

 moval. The town of Leeds pays about fourteen thousand pounds a 

 year for the scavenging of the streets and the emptying of ash-pits. 

 Nearly every house in Leeds supplies in the way of cinders at least 

 twice as much ash-pit refuse as it might do, were the fireplaces proper- 

 ly constructed. The ash-pit refuse of Leeds is burned in a " de- 

 structor," and the cinders in the refuse provide not only heat enough 

 for its reduction to a mineral residue, but spare heat for driving two 

 sixty-horse-power engines, and for consuming a reasonable amount of 

 pigs, etc., killed by or on account of disease. 



These three great evils, evils affecting not only individuals, but the 

 community, waste of fuel and heat, production of soot, production of 

 cinders, are a direct result of the violation of the correct principles in 

 fireplace construction. 



Let us next inquire what are the principles which promote good 

 combustion in an open fireplace i. e., what are the conditions which 

 are essential to enable fuel to give out to a room " good money's worth 

 in heat." That such a result may be obtained, fuel must burn well 

 but not rapidly. Two things in combination are essential to the com- 

 bustion of fuel a supply of oxygen, and a high temperature i. e., 

 plenty of heat around the fuel. If fuel be burned with a hot jacket 

 around it, a very moderate amount of oxygen will sustain combustion, 

 and, if the supply of oxygen be moderate, combustion is slow. Burn 

 coal with a chilling jacket around it, a rapid conductor like iron, and 

 it needs a fierce draught of oxygen to sustain combustion, and this 

 means rapid escape of actual heat, and also of potential heat in un- 

 burned gases and smoke, up the chimney. This is the key to the whole 

 position ; this is the touchstone by which to test the principles of fire- 

 place construction. 



Few people probably realize the exact conditions of combustion, 

 which may be well illustrated from the process of manufacture of coal- 

 gas. In coal we have three kinds of constituents : One mineral, in- 

 combustible, seen in the ash residue, which for good coal amounts to 

 barely three per cent. The second, volatile, and which, under the 

 influence of heat becoming gaseous, appears in an open fire as tall 

 flame and smoke, and, where combustion is imperfect, produces soot. 

 The third constituent is carbon or charcoal, familiarly known as coke 

 or cinder, and when burning gives a short, shallow, bluish flame. The 

 carbon and the volatile portions can be raised to a high temperature, 

 and still will not burn unless oxygen be brought into contact with 

 them. 



In the manufacture of gas, coal is raised to a high temperature, 

 and the gases are driven off by roasting the coal in an oven from 

 which air, i. e., oxygen, is shut out. The gases are conducted away, 

 cooled, purified, and stored for future use in a gasometer ; the com- 



