256 SCIENCE PROGRESS 



theories and hypotheses were suggested. The scheme which 

 found most favour with Arabian alchemists involves, as we shall 

 see, the possibility of the transmutation of the metals as a 

 necessary consequence. It cannot be too often repeated that 

 the chemical system of the Muslims was a logical system, in 

 accord with the experimental work of the time, and limited 

 only by that experimental work, as all theories must be limited 

 by the practical experience of the period in which they are 

 current. 



It was believed by the Muslim chemists, using Aristotelian 

 notation, that the Prime Matter of the universe, before it can 

 become a definite substance, must be united with Specific Form, 

 and according to the specific form which it receives the prime 

 matter gives rise to all the various substances of which the 

 universe is composed. The most elementary kinds of specific 

 form are those which, united to the Prime Matter, give rise 

 to Fire, Air, Water, and Earth, the " Four Elements " of 

 AristoteHan philosophy. Each of the Four Elements has 

 qualities which distinguish it from the others ; thus, fire is 

 hot and dry, air is hot and moist, water is moist and cold, 

 earth is cold and dry. Any one Element may pass directly 

 into another with which it has one property in common, by 

 means of that property ; thus, if air is heated it becomes fire, 

 and if water is cooled it becomes earth. It is clear, there- 

 fore, that the Four Elements in one way resemble our three 

 " physical states," with the addition of the state of incan- 

 descence. 



All substances are composed of the Four Elements in 

 varying proportions and different combinations, but the Prime 

 Matter is the same in all. By changing the Specific Form, 

 transmutation of one substance into another is therefore 

 possible : the first stage in such a change is called " Corruption," 

 which means that the original specific form is lost, and the 

 second, which follows immediately, is called " Generation," 

 and implies that the Prime Matter takes on another Specific 

 Form. 



The three main classes of compound substances are Vege- 

 table, Mineral, and Animal, but these are again divided into 

 many species. One of the species of Minerals is the MetaHic. 

 All metals are therefore one in species, i.e. they are composed 

 (hke all other substances) of the Prime Matter, united with 

 the same Specific Form. If this is so, how are we to account 

 for the existence of seven different metals, gold, silver, copper, 

 lead, tin, iron, and mercury ? The theory of the Arabian 

 alchemists was that the perfect state of the metallic species is 

 represented by gold. Other metals have failed to reach the 

 state of perfection, owing to the presence in them of certain 



