TEE DAWN OF MODERN CHEMISTRY 9 



theory in later centuries. This was the theory of the five elements — 

 fire, air, water, earth and ether or essence. It seems very probable 

 that this theory was derived originally from ancient Hindoo philosophy, 

 because in ancient Hindoo classics it is more completely elaborated than 

 by Aristotle. The four elements — air, fire, water, earth — were not 

 considered as distinct elementary substances, according to our modern 

 definition of an element, but rather as determining qualities. 



Thus fire combined the qualities of warmth and dryness; air — 

 warmth and moistness; water — cold and moistness; earth — cold and 

 dryness. All substances were considered as combinations of these ele- 

 mentary qualities, or in some sense as composed of these elements. The 

 fifth element, ether or "essence," was more subtle and less clearly de- 

 fined. It was supposed to be capable of taking all forms, and finally 

 came to be identified with the "materia prima," or primal matter, out 

 of which all other forms of matter were supposed to be born. 



The Aristotelian notion of the four elements also implied the 

 possibility of the change of one element to another. Thus when water 

 evaporated by heat it became air ; that is, by the addition of warmth, it 

 changed from cold and moist to warm and moist, the properties of air. 

 This idea among later alchemists served to justify the notion of the 

 transmutability of the elements, that will-o'-the-wisp of chemists for 

 many centuries. But this idea of the possibility of transmuting one 

 element into another as of the baser metals into gold and silver re- 

 ceived greater vitality from the observations and experiences, of the 

 metallurgists upon the occurrence, preparation and alloys of the metals, 



The metals known to the ancients were seven in number, gold, silver, 

 lead, mercury, iron, copper and tin, though they were not considered as 

 elements. Other metals indeed entered into their alloys, but they were 

 not recognized by them as separate or distinct from those already 

 named. Arsenic was known, though not considered as a metal. Bis- 

 muth and zinc and antimony began to be recognized as distinct sub- 

 stances about the beginning of the sixteenth century. As methods of 

 analysis were rudimentary even at this later date, and as there was no 

 realization of the concept of an element of unvarying composition and 

 properties, and as the metals were obtained in varying degrees of 

 purity or admixture, it can be understood how the changes in appear- 

 ance and properties of the metals, as obtained from their ores, was 

 believed to be due to a partial transmutation in the Aristotelian sense. 



In the alloying of various metals, the character of the alloys was 

 changed in ways that easily suggested actual changes in the character 

 of the metals themselves. Thus we know that the Egyptians con- 

 sidered certain alloys of gold and silver as a distinct metal " electrum." 

 The frequent occurrence of some gold in silver as obtained from its 

 ores also easily suggested the idea that this gold had in some way been 

 produced from the silver. 



