192 EIGHTEENTH CENTURY. PT. in. 



ness and good-temper. He loved his science too well to 

 hinder its progress by angry disputes ; and by imparting 

 this spirit to his pupils he did almost as much for the 

 spread of medical science as by the facts which he taught 

 them. 



But besides his influence upon medicine in general there 

 was one particular study which Boerhaave may be said to 

 have founded ; this was the chemistry of living substances, 

 or organic chemistry. You will remember that the false 

 science of alchemy had always been much mixed up with 

 chemistry, and the alchemists had some strange mystical 

 notions about ' vital fluids/ which they supposed to exist in 

 animals and plants, and to cause their life and growth. Little 

 by little, however, more correct ideas had grown up in the 

 1 6th and lyth centuries about the nature of life. Vesalius, 

 Harve^, Malpighi, Grew, and many others, had gradually 

 described more and more accurately the working of the dif- 

 ferent organs of a living being, and now Boerhaave went 

 farther, and tried to discover by means of chemistry of what 

 materials these organs themselves are composed. 



In the same way that Geber had decomposed or divided 

 up inorganic substances, such as metals and earths, by distil- 

 lation and sublimation (see p. 44), so Boerhaave proposed to 

 decompose the organic substances of which plants and ani- 

 mals are made, and to discover the materials contained in 

 them. To accomplish this he took a plant, such as rosemary, 

 and putting fresh moist leaves of it into a furnace, heated 

 them gently and drove out all the moisture, which he col- 

 lected in a separate vessel. When this moisture had cooled 

 down into a liquid he examined it and found that it was 

 made up of water, and of different kinds of oils and 

 essences, according to the plant he had taken. For in- 

 stance, from rosemary he got an essence with the peculiar 



