iSS Medicine, [Chap. IV. 



th.e blood was discovered, was wholly concealed 

 from us." 



It will scarcely be necessary to add to what is 

 ah'cady stated concerning Hook and Mayow, that 

 Mr. Boyle and Dr. Hales were much engaged on 

 the same subject, and that the latter particularly 

 w^as greatly useful by his experiments and re 

 searches in pneumatic philosophy, which paved the 

 way for the brilliant uuprovements of his successors 

 in that inquiry. 



The splendid progress of pneumatic chemistry 

 which ennobles the last twenty-six years of the 

 eighteenth century, has been detailed in another 

 place. The discovery of oxygen, and the analysis 

 of the atmosphere, are prominent points in that 

 progress ; and they likewise constitute the basis of 

 the principles which were afterwards so successfully 

 applied to explain the nature and objects of the 

 function of respiration. 



It is universally known, that the merit of taking 

 the lead in the application of the principles of 

 pneumatic chemistry to explain the function of the 

 lungs is due to Dr. Priestley*. h\ the year 1774 

 he discovered the existence, and many of the pro- 

 perties, of oxiigen. JMr. Scheele made the same 

 discovery nearly at tlie same time. Not long after- 

 wards these two pliilosophers demonstrated that 

 the quant itj^ of oxygenous gas is diminished in 

 respiration. ]n 177^) Lavoisier proved that atmo- 

 spheric air is compounded of oxygen and azote, 



* For a considerable portion of the fads detailed in several of 

 the following paragraphs on the subject at' respiration, the author 

 is indebted to a very respectable work, entitled A Si/.stem of Che- 

 m^iiry, by 'i'honias Thonj^un, M. D. 4 vols, i5\o, 1802. 



