S2 FARADAY 



with* common air, and the water which forms the bubble car- 

 ries it down. But now, if I inhale hydrogen gas into my lungs 

 (it does no harm to the lungs, although it does no good to 

 them), see what happens. [The lecturer inhaled some hydro- 

 gen, and, after one or two ineffectual attempts, succeeded in 

 blowing a splendid bubble, which rose majestically and slowly 

 to the ceiling of the theatre, where it burst.] That shows you 

 very well how light a substance this is ; for, notwithstanding 

 all the heavy bad air from my lungs, and the weight of the 

 bubble, you saw how it was carried up. I want you now to 

 consider this phenomenon of weight as indicating how exceed- 

 ingly different particles are one from the other; and I will 

 take as illustrations these very common things, air, water, the 

 heaviest body, platinum, and this gas, and observe how they 

 differ in this respect; for if I take a piece of platinum of 

 that size (Fie. 29), it is equal to the weight of portions of 



re*. 



Platinum*. 



FIG. 29 



water, air, and hydrogen of the bulks I have represented in 

 these spheres; and this illustration gives you a very good 

 idea of the extraordinary difference with regard to the 

 gravity of the articles having this enormous difference in 

 bulk. [The following tabular statement having reference to 

 this illustration appeared on the diagram-board.] 



Hydrogen .... i 



Air 14.4 x 



Water 11943 829 



Platinum .... 356774 17831 or-S 



