24 COMBUSTION. 



The argand lamp is so constructed that the combustion 

 is complete, and consequently it does not smoke. This 

 is effected by the wick being of a circular shape, and so 

 contrived that a constant supply of air is admitted to 

 every part of it, which affords sufficient heat to burn 

 the smoke as it is formed. 



Sir Richard Phillips explains the theory of combus- 

 tion in the following manner :* " Combustion," he ob- 

 serves, " is a case of decomposition and recomposition, 

 and the intermediate effects or accidents are heat and 

 light. A combustible body contains hydrogen and 

 carbon. The air in which the combustion takes place 

 consists of oxygen and nitrogen ; and if a definite bulk 

 of air is employed, the oxygen disappears, and may be 

 found in the products of the combustion. To under- 

 stand the process it is necessary to affix a precise idea 

 to gas, which, in a word, is atoms in intense orbit mo- 

 tions resulting from primary force in right lines, .and 

 the reaction of other atoms in the space. Oxygen then 

 consists of such atoms, and of course if they are fixed, 

 they transfer their momenta to bodies fixing them: if 

 to atoms of hydrogen, they condense as water, with 

 heat to surrounding bodies ; and if to carbon, they form 

 carbonic acid, with heat to surrounding bodies. Com- 

 bustion begins by applying heat or excitement, as lighted 

 paper, or a taper, to the combustible. This melts the 

 tallow, and raises into gas the latent hydrogen in excite- 

 ment, that is, in orbits too large for the space ; and a 

 vacuum is created, which the oxygen fills with eight 

 times the force, becoming fixed by the hydrogen both 

 in atoms of water, and by the carbon in carbonic acid. 

 The oxygen is thus fixed, and the air so far decom- 

 posed, but the friction at the wick raises an intense 

 local heat, which, unable otherwise to escape, acts on 

 the atoms of air, and creates in them a general propul- 

 sion, which we call light, the heat being the concentrated 

 motion at the spot." 



Inflammation, Ignition, and Detonation or Explosion, 

 are terms used to express the different states of com- 



* See " A Million of Facts," by Sir R. Phillips. 



