36 CONVERSATIONS ON THE 



der, one of the most powerful su)>stances in 

 the world. Remember this, boys, and try to 

 learn all the uses and properties of all sorts 

 of things, and who knows but that you may 

 make yourselves famous, or, which is better 

 5till, useful, one of these days by some very im- 

 portant discovery. Good night, boys." 

 " Good night, Uncle Philip." 



