ix] Doctrines of Respiration. 227 



" curious, add absolutely nothing to medical practice ; and it is 

 " not meet to waste any more time upon them." 



Thus the great exponent of the chemistry of his time, and 

 especially of the chemistry of combustion, touched lightly the 

 key to one of the most important of the chemical problems of 

 the living body, and having touched it, deliberately drew his 

 hand away. 



We naturally turn from Stahl to learn the views of the 

 other great chemist of the period, Hermann Boerhaave. We 

 must remember that the two were men of very unlike character. 

 Stahl was an investigator and an eager promulgator of new 

 views ; Boerhaave, though he did pursue with zeal and success 

 various experimental inquiries, was in the main an expositor 

 and an eclectic critic of the views of others. He put forward 

 no new theories of his own about breathing, and was content 

 to point out the conclusions which could be drawn from the 

 various results of other inquirers. In his great work on the 

 Elements of Chemistry, which deservedly became the text-book 

 of the age, after dwelling at some length on air and its properties - 

 in a manner which shews his profound acquaintance with all 

 the researches of the time, he has a passage entitled " There is 

 " in air a wholly special virtue." In this, after shewing that all 

 living things stand in need of air, and after pointing out the 

 effect of air on the colour of blood, in turning dark blood scarlet, 

 he ends as follows. 



" All these things prove that air possesses a certain occult 

 " virtue which cannot be explained by any of those properties of 

 " air which have hitherto been investigated. That in this virtue 

 " the secret food of life lies hidden some chemists have asserted. 

 " But what it really is, how it acts and what it exactly brings 

 "about is still obscure. Happy the man who will discover 

 "it!" 



We may recognize in this the sagacious observer groping 

 round the truth but unable to lay his finger exactly on it. 

 What were Boerhaave's more detailed teachings concerning 

 breathing may be inferred from the exposition given by 

 his illustrious pupil Haller; for Haller in the main followed 

 the lines of his great Master, differing from him chiefly in the 



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