CHEMICAL HISTORY OF A CANDLE 109 



altogether cause it to burn with a flame. And here is some 

 pulverized iron, or iron filings. Now I purpose burning 

 these two things together. I have a little mortar in which 

 I will mix them. (Before I go into these experiments, let 

 me hope that none of you, by trying to repeat them for fun's 

 sake, will do any harm. These things may all be very 

 properly used if you take care, but without that much mis- 

 chief will be done.) Well, then, here is a little gunpowder, 

 which I put at the bottom of that little wooden vessel, and 

 mix the iron filings up with it, my object being to make the 

 gunpowder set fire to the filings and burn them in the air, 

 and thereby show the difference between substances burning 

 with flame and not with flame. Here is the mixture; and 

 when I set fire to it you must watch the combustion, and you 

 will see that it is of two kinds. You will see the gunpowder 

 burning with a flame and the filings thrown up. You will 

 see them burning, too, but without the production of flame. 

 They will each burn separately. [The lecturer then ignited 

 the mixture.] There is the gunpowder, which burns with a 

 flame, and there are the filings: they burn with a different 

 kind of combustion. You see, then, these two great dis- 

 tinctions; and upon these differences depend all the utility 

 and all the beauty of flame which we use for the purpose 

 of giving out light. When we use oil, or gas, or candle for 

 the purpose of illumination, their fitness all depends upon 

 these different kinds of combustion. 



There are such curious conditions of flame that it requires 

 some cleverness and nicety of discrimination to distinguish 

 the kinds of combustion one from another. For instance, 

 here is a powder which is very combustible, consisting, as 

 you see, of separate little particles. It is called lycopodium.C) 

 and each of these particles can produce a vapor, and pro- 

 duce its own flame; but, to see them burning, you would 

 imagine it was all one flame. I will now set fire to a quan- 

 tity, and you will see the effect We saw a cloud of flame, 

 apparently in one body; but that rushing noise preferring 

 to the sound produced by the burning] was a proof that the 

 combustion was not a continuous or regular one. This is 



* Lycopodium is a yellowish powder found in the fruit of the club 

 (.Lycopodium clavatum). It is used in fire-works. 



