CH. VII. CHEMISTRY OF GEBER. 43 



CHAPTER VIL 



SCIENCE OF THE ARABS (CONTINUED). 



Geber, or Djafer, the founder of Chemistry — His Explanation of Dis- 

 tillation—Of Sublimation — Discovers that some Metals increase in 

 weight when heated — Discovers strong Acids — Nitric Acid- 

 Sulphuric Acid — Discovery of Sal- Ammoniac by the Arabs — Arabs 

 mix up Astronomy with Astrology — Albategnuis calculates the 

 Length of the Year — Mohammed Ben Musa, first writer on Algebra 

 — Uses the Indian Numerals — Gerbert introduces them into Europe 

 — Alhazen's discoveries in Optics — His Explanation why only one 

 image of each object reaches the Brain — His discovery of Refrac- 

 tion, and of its effect on the light of the Sun, Moon, and Stars — His 

 discovery of the magnifying power of rounded glasses. 



Geber's discoveries in Chemistry, 800-900.— The greatest 

 of the Arabian alchemists was a man named Geber, or 

 Djafer, who was born In Mesopotamia about a.d. 830. 

 He has been called the * Founder of Chemistry,' for though, 

 like his countrymen, he spent much of his time in trying to 

 make gold, yet he is the first who, as far as we know, made 

 really useful chemical experiments. 



He explains in his works many of the methods we now 

 use in chemistry. For example, he states that if you boil 

 water, the vapour (or spirit as he calls it) will rise up, and 

 you can collect it and cool it down again in another vessel ; 

 and it will then be pure, because any solid matter such as 

 sand or salt, which does not turn readily into vapour, will 

 remain behind in the first vessel. Again, if you heat wine or 



