DOCTRINE OF ACID AND ALKALI. 125 



fluids, and applies to them modes of cure founded 

 upon this doctrine. We have here to speak, not df 

 his physiological, but of his chemical, views. 



The distinction of acid and alkaline bodies 

 (acidum, lixivum) was familiar before the time of 

 Sylvius ; but he framed a system, by considering 

 them both as eminently acrid and yet opposite, and 

 by applying this notion to the human frame. Thus 2 

 the lymph contains an acid, the bile an alkaline 

 salt. These two opposite acrid substances, when 

 they are brought together, neutralize each other 

 (infringunt), and are changed into an intermediate 

 and milder substance. 



The progress of this doctrine, as a physiological 

 one, is an important part of the history of medical 

 science in the seventeenth century ; but with that 

 we are not here concerned. But as a chemical 

 doctrine, this notion of the opposition of acid and 

 alkali, and of its very general applicability, struck 

 deep root, and has not been eradicated up to our 

 own time. Boyle, indeed, whose disposition led 

 him to suspect all generalities, expressed doubts 

 with regard to this view 3 ; and argued that the sup- 

 position of acid and alkaline parts in all bodies was 

 precarious, their offices arbitrary, and the notion 

 of them unsettled. Indeed it was not difficult to 

 show, that there was no one certain criterion to 



* De Methodo Medendi, Amst. 1679. Lib. ii. cap. 28, sects. 8 

 Und 53. 



3 Shaw's Boyle, iii. p. 432. 



