104 HEAT. 



panied with all you have previously seen, to show 

 you how we procure heat. And now for the effects 

 of this power. We need not consider many of 

 them on the present occasion, because when you 

 have seen its power of changing ice into water 

 and water into steam, you have seen the two 

 principal results of the application of heat. I 

 want you now to see how it expands all bodies 

 all bodies but one, and that under limited 

 circumstances. Mr. Anderson will hold a lamp 

 under that retort, and you will see the moment 

 he does so that the air will issue abundantly 

 from the neck which is under water, because the 

 heat which he applies to the air causes it to ex- 

 pand. And here is a brass rod ( fig. 32) which 



Fig. 32. 



1 



goes through that hole and fits also accurately 

 into this gauge; but if I make it warm with 



