CHEMICAL HISTORY OF A CANDLE 121 



full of steam, or else it would not force its way out. Yon 

 see also that the flask contains a substance very much larger 

 than the water, for it fills the whole of the flask over and 

 over again, and there it is blowing away into the air; and 

 yet you can not observe any great diminution in the bulk 

 of the water, which shows you that its change of bulk is 

 very great when it becomes steam. 



I have put our iron bottles containing water into this 

 freezing mixture, that you may see what happens. No 

 communication will take place, you observe, between the 

 water in the bottles and the ice in the outer vessel. But 

 there will be a conveyance of heat from the one to the other, 

 and if we are successful we are making our experiment 

 in very great haste I expect you will by-and-by, so soon 

 as the cold has taken possession of the bottles and their 

 contents, hear a pop on the occasion of the bursting of the 

 one bottle or the other, and, when we come to examine the 

 bottles, we shall find their contents masses of ice, partly 

 inclosed by the covering of iron which is too small for them, 

 because the ice is larger in bulk than the water. You know 

 very well that ice floats upon water; if a boy falls through 

 a hole into the water, he tries to get on the ice again to 

 float him up. Why does the ice float? Think of that, and 

 philosophize. Because the ice is larger than the quantity 

 of water which can produce it, and therefore the ice weighs 

 the lighter and the water is the heavier. 



To return now to the action of heat on water. See what a 

 stream of vapor is issuing from this tin vessel. You observe, 

 we must have made it quite full of steam to have it sent out 

 in that great quantity. And now, as we can convert the 

 water into steam by heat, we convert it back into liquid 

 water by the application of cold. And if we take a glass, 

 or any other cold thing, and hold it over this steam, see 

 how soon it gets damp with water : it will condense it until 

 the glass is warm it condenses the water which is now 

 running down the sides of it. I have here another ex- 

 periment to show the condensation of water from a va- 

 porous state back into a liquid state, in the same way 

 as the vapor, one of the products of the candle, was 

 condensed against the bottom of the dish and obtained 



