ROBERT BOYLE. 13 



By his experiments with this machine Boyle made several 

 important discoveries with regard to the air, the principal ot 

 which he details in the three successive parts of the work we 

 have mentioned. Having given so commodious a form and 

 position to the vessel out of which the air was to be extracted 

 (which, after him, has been generally called the receiver, a 

 name, he says, first bestowed upon it by the glassmen), that he 

 could easily introduce into it anything which he wished to make 

 the subject of an experiment, he found that neither flame would 

 burn nor animals live in a vacuum, and hence he inferred the 

 necessity of the presence of air both to combustion and animal 

 life. Even a fish, immersed in water, he proved, would not 

 live in an exhausted receiver. Flame and animal life, he 

 showed, were also both soon extinguished in any confined 

 portion of air, however dense, although not so soon in a given 

 bulk of dense as of rarefied air; nor was this, as had been 

 supposed, owing to any exhalation of heat from the animal 

 body or the flame, for the same thing took place when they 

 were kept in the most intense cold, by being surrounded with 

 a frigorific mixture. What he chiefly sought to demonstrate, 

 however, by the air-pump was, the extraordinary elasticity, or 

 spring, as he called it^ of the air. It is evident, from the 

 account that has been given of the principle of this machine, 

 that, if the pump be worked ever so long, it never can produce 

 in the receiver a strictly perfect vacuum ; for the air expelled 

 from the barrel by the last descent of the piston must always 

 be merely a portion of a certain quantity, the rest of which will 

 be in the receiver. The receiver, in truth, after the last stroke 

 of the piston, is as full of air as it was at first ; only that by 

 which it is now filled is so much rarefied and reduced in 

 quantity, although it occupies the same space as before, that 



