CH. xvi. RESPIRATION AND COMBUSTION. 133 



at first the water inside the jar sank down, because the air, 

 being heated, expanded and took up more room. Then after 

 a time the camphor ceased to burn, the jar cooled down, and 

 the water rose again higher than before, till it stood above the 

 water outside. The camphor was not all consumed, but 

 when he tried to light it again he could not succeed. Why 

 was this ? ' Because,' said Mayow, ' there are no fire-air 

 particles left in the jar to make the camphor burn, and the 

 using up of these particles has made the rest of the air shrink 

 and take up less space.' 



He now wished to compare burning with breathing, so 

 he put a mouse in a cage and hung it inside the bell-jar, 

 which he arranged over the water as before. Little by little 

 as the mouse breathed the water crept up inside the jar, until 

 when it had risen to a certain height the mouse drooped and 

 died. It was clear, therefore, that animals in breathing use 

 up some portion of the air. But is it the same portion which 

 the flame uses? Many people would have jumped at this 

 conclusion, but Mayow was not content till he had proved 

 it by another experiment. He put a lighted candle and a 

 mouse together inside the bell-jar. The water now rose 

 much faster than before ; the candle went out first, and then 

 the mouse drooped as soon as the water had risen to the 

 same height as in the other experiment. He was now 

 certain that the candle and mouse both used up the same 

 fire-air particles ; but to make still more sure, he put a candle 

 under a bell-jar where the air had been spoiled by breathing, 

 and it went out directly. 



His next step was to try whether air was lighter or 

 heavier after thejire-air had been used up. To do this he 

 put two mice into the jar, one at the top and the other at 

 the bottom ; the one at the top drooped and died, while the 



