CHEMICAL HISTORY OP A CANDLE 173 



done nothing to the lime-water; in the other case, nothing 

 has come to the lime-water but my respiration, and you see 

 the difference in the two cases. 



Let us now go a little farther. What is all this process 

 going on within us which we can not do without, either day 

 or night, which is so provided 

 for by the Author of all things 

 that He has arranged that it 

 shall be independent of all will ? 

 If we restrain our respiration, 

 as we can to a certain extent, 

 we should destroy ourselves. 

 When we are asleep the organs 

 of respiration and the parts 

 that are associated with them 

 still go on with their action, 

 so necessary is this process of 

 respiration to us, this contact 

 of the air with the lungs. I 

 must tell you, in the briefest "' "-" ^ FIG g 

 possible manner, what this 

 process is. We consume food; the food goes through that 

 strange set of vessels and organs within us, and is brought 

 into various parts of the system, into the digestive parts 

 especially; and alternately the portion which is so changed 

 is carried through our lungs by one set of vessels, 

 while the air that we inhale and exhale is drawn into 

 and thrown out of the lungs by another set of vessels, so 

 that the air and the food come close together, separated 

 only by an exceedingly thin surface: the air can thus act 

 upon the blood by this process, producing precisely the same 

 results in kind as we have seen in the case of the candle. 

 The candle combines with parts of the air forming carbonic 

 acid, and evolves heat; so in the lungs there is this curious, 

 wonderful change taking place. The air entering, combines 

 with the carbon (not carbon in a free state, but, as in this 

 case, placed ready for action at the moment), and makes 

 carbonic acid and is so thrown out into the atmosphere, and 

 thus this singular result takes place; we may thus look 

 upon the food as fuel. Let me take that piece of sugar, which 



