PART II. HEATING. 



SECTION I/ 



PRINCIPLES OF COMBUSTION. 



1. To warm hot-houses, etc., most economically and efficiently, 

 we must study not only the principles of heating, but, also, 

 the principles of combustion. And as we are yet far from, 

 having obtained a complete knowledge of the most profitable 

 manner of submitting coal and other kinds of fuel to the process 

 of combustion, or, of applying the caloric so obtained to increase 

 the temperature of hot-houses, it will, therefore, be desirable to 

 begin at the beginning of this part of our work, and before treat- 

 ing on the different mechanical contrivances in common use for 

 the generation and diffusion of heat by combustion, let us first 

 consider the principles upon which these ends are to be obtained. 



The subject before us involves a consideration of the nature 

 and properties of the various kinds of fuel. It examines the 

 chemical action of their several constituents on each other. It 

 applies those inquiries to the class of chemical results which 

 may be useful, and avoids those which are injurious. It involves 

 also, in an especial degree, the closest observation on the sepa- 

 rate influences which each of the constituents of atmospheric 

 air exercises on combustible bodies, in the generation of those 

 extraordinary elements of nature, heat and light. And, finally, 

 it investigates the cause and character of flame and smoke, and 

 the influence these have on the former. 



Economy of fuel being one of the most important points to be 

 sought for in a heating apparatus, we must inquire whether our 

 common furnaces be so constructed as to give us the maximum 

 quantity of caloric, for the fuel that is consumed. We, there- 



