CHEMICAL HISTORY OF A CANDLE 



161 



ubic Foo 



r 



turbid and white, which is proof of the presence of carbonic 

 acid. 



Then it is a very weighty gas; it is heavier than the 

 atmosphere. I have put their respective weights at the 

 lower part of this table, along with, for comparison, the 

 weights of the other gases we have been examining: 



Pint. Cubic Foot. 



Hydrogen fgrs. 



Oxygen Il^j 



Nitrogen i<yfr 



Air loflj 



Carbonic acid i6j 



A pint of it weighs 16 1-3 grs., and a cubic foot weighs I 9-10 

 oz., almost two ounces. You can see by many experiments 

 that this is a heavy gas. Suppose I take a glass contain- 

 ing nothing else but air, and from this vessel containing 

 the carbonic acid I attempt to pour a little of this gas into 

 that glass I wonder whether any has gone in or not. I 

 can not tell by the appearance, but I can in this way [intro- 

 ducing the taper]. Yes, there it is, you see; and if I were to 

 examine it by lime-water, I should find it by that test also. 

 I will take this little bucket, and put it 

 down into the well of carbonic acid 

 indeed, we too often have real wells of 

 carbonic acid and now, if there is 

 any carbonic acid, I must have got to 

 it by this time, and it will be in this 

 bucket, which we will examine with a 

 taper. There it is, you see: it is full 

 of carbonic acid. 



There is another experiment by 

 which I will show you its weight 

 I have here a jar suspended at one 

 end of a balance it is now equipoised; 

 but when I put this carbonic acid into 

 the jar on the one side which now con- 

 tains air, you will see it sink down at once because of 

 the carbonic acid that I pour into it And now, if I 

 examine this jar with the lighted taper, I shall find that 

 the carbonic acid has fallen into it, and it no longer 

 has any power of supporting the combustion. If I blow 



HC VOL. xxx F 



FIG. 84 



