4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 76 



since it is introduced in the form of air, carries with it another 

 ^2 parts of nitrogen, the increase in volume is seen to be decidedly 

 significant. One result is to lower the working temperature within 

 the furnace precisely as the introduction of cool air into a room lowers 

 the room temperature. Another ill effect is that since the flue gases 

 carry off heat, any material increase in the volume of flue gases gives 

 a correspondingly significant increase in the heat thus escaping. 



Analyzing the results in reaction (4), it develops that only 

 one-fourth of the carbon has been fully burned, the other three- 

 fourths being two-thirds wasted ; in other words, there has been only 

 a 50 per cent extraction of heat units. 



In short, adequacy of results is to be attained only as the require- 

 ments of exact chemical laws are met with exactitude. Deviations 

 resulting in as much as 50 per cent loss in efficiency may easily 

 go unnoticed in the absence of any definite check in the way of 

 chemical control. As a matter of fact, it is not too much to say that 

 modern industry is built around chemical control, and it is a striking 

 fact that the one chemical process involving, in the aggregate, the 

 largest capital outlay remains to-day largely subject to rule of thumb 

 methods. 



Domestic Application 



The principles underlying effective combustion apply to the house- 

 hold furnace and to the power house installation ahke. There is 

 this difference however : In the former the furnace receives only 

 casual attention and that of a perfunctory, inexpert nature, while 

 the latter is being constantly ministered to by specially trained 

 attendants. Accordingly, the smaller installations are subject to a 

 handicap which prevents any rigorous application of chemical con- 

 trol, but this does not mean that an inteUigent application of the 

 general principles may not be made productive of significant results, 

 especially in view of the present high fuel costs. It is not at all 

 uncommon to encounter one consumer burning twelve or fourteen tons 

 of coal while another operating under essentially similar conditions gets 

 by with six or eight tons. Discrepancies such as these indicate conclu- 

 sively the extent to which irregularities in practice may lead to readily 

 preventable losses. 



The general principles of effective combustion in substance boil 

 down to having the furnace in good working order ; exercising effec- 

 tive draft control ; and using the coal best suited to the requirement. 

 The defect most commonly encountered in the upkeep of the furnace 

 itself is that of dirty flues. A one-eighth inch coating of soot pro- 



