THE CONTINUITY OF SCIENCE 51 



all transmutations, and be for mankind a cure for 

 all ailments, even that of growing old. The writings 

 that have been attributed to Geber show the advances 

 that chemistry made through the experiments of the 

 Arabs. They produced sulphuric and nitric acids, 

 and aqua regia, able to dissolve gold, the king of 

 metals. They could make use of wet methods, and 

 form metallic salts such as silver nitrate. Labora- 

 tory processes like distilling, filtering, crystallization, 

 sublimation, became known to the Europeans through 

 them. They obtained potash from wine lees, soda 

 from sea-plants, and from quicksilver the mercuric 

 oxide which played so interesting a part in the later 

 history of chemistry. 



Much of the science lore of the Arabs arose from 

 their extensive trade, and in the practice of medi- 

 cine. They introduced sugar-cane into Europe, im- 

 proved the methods of manufacturing paper, discov- 

 ered a method of obtaining alcohol, knew the uses 

 of gypsum and of white arsenic, were expert in 

 pharmacy and learned in materia medica. They are 

 sometimes credited with introducing to the West the 

 knowledge of the mariner's compass and of gun- 

 powder. 



Avicenna (980-1037), the Arab physician, not 

 only wrote a large work on medicine (the Canwi) 

 based on the lore of Galen, which was used as a text- 

 book for centuries in the universities of Europe, but 

 wrote commentaries on all the works of Aristotle. 

 For Averroes (1126-1198), the Arab physician and 

 philosopher, was reserved the title " The Commen- 

 tator," due to his devotion to the works of the Greek 

 biologist and philosopher. It was through the com- 



