CHEMICAL HISTORY OF A CANDLE 113 



[The lecturer then ignited the mixture by means of sul- 

 phuric acid.] Now, from the appearance of things, you 

 can judge for yourselves whether they produce solid matter 

 in burning. I have given you the train of reasoning which 

 will enable you to say whether they do or do not; for what 

 is this bright flame but the solid particles passing off? 



Mr. Anderson has in the furnace a very hot crucible. I 

 am about to throw into it some zinc filings, and they will 

 burn with a flame like gunpowder. I make this experiment 

 because you can make it well at home. Now I want you 

 to see what will be the result of the combustion of this zinc. 

 Here it is burning burning beautifully like a candle, I may 

 say. But what is all that smoke, and what are those little 

 clouds of wool which will come to you if you can not come to 

 them, and make themselves sensible to you in the form of 

 the old philosophic wool, as it was called. We shall have 

 left in that crucible, also, a quantity of this woolly matter. 

 But I will take a piece of this same zinc, and make an ex- 

 periment a little more closely at home, as it were. You will 

 have here the same thing happening. Here is the piece of 

 zinc; there [pointing to a jet of hydrogen] is the furnace, 

 and we will set to work and try and burn the metal. It 

 glows, you see; there is the combustion; and there is the 

 white substance into which it burns. And so, if I take that 

 flame of hydrogen as the representative of a candle, and 

 show you a substance like zinc burning in the flame, you 

 will see that it was merely during the action of combustion 

 that this substance glowed while it was kept hot; and if I 

 take a flame of hydrogen and put this white substance from 

 the zinc into it, look how beautifully it glows, and just 

 because it is a solid substance. 



I will now take such a flame as I had a moment since, and 

 set free from it the particles of carbon. Here is some cam- 

 phene, which will burn with a smoke; but if I send these 

 particles of smoke through this pipe into the hydrogen 

 flame you will see they will burn and become luminous, 

 because we heat them a second time. There they are. Those 

 are the particles of carbon reignited a second time. They 



and perchlorate of potassa. The oxide of chlorine inflames the sulphuret of 

 antimony, which is a combustible body, and the whole mass instantly burst* 

 into flame. 



