RESPIRA riON 



60 1 



The actual constituent of the air that is required was not recognised until the 

 experiments of John Mayow (1674), who showed that it is what we now call 

 "oxygen," but which he called " spiritus nitro-aereus," identifying it with that 



FIG. 184. PORTRAIT OF JOHN MAYOW. 



(Prefixed to his book, 1674. ) 



constituent on which ordinary combustion depends. Mayow was also aware that 

 this substance entered into the blood, and was indispensable for vital activity (see 

 Domian's reprint, pp. 27 and 38). 



The reader will probably be interested to have before him the actual words used in one or 



