Mr. G. F. Rodwell on the Theory of Phlogiston. 5 



Nyaya systems ; and it appears probable that it was recognized 

 as a fifth element prior to the year 900 B.C. It was believed 

 to be all-pervading ; and its special quality was, that sound ori- 

 ginates from its motion, and is transmitted by it. 



In considering the application of the four-element theory, we 

 must bear in mind that the elements were not viewed in their 

 strictly literal sense; it was not believed that there is but one 

 kind of fire, air, water, and earth. Light, the heat inherent in 

 all bodies, name, incandescent bodies, together with lightning 

 and all visible manifestations of electricity, were included with 

 the element fire*. Smoke, steam, and whatsoever appertained 

 to gaseity, were included with air. Blood, milk, and wine (the 

 most familiar liquids after water to the early races) were included 

 with water. Finally rocks, cultivable land, and metals (essen- 

 tially different in the eyes of the most primitive man) were in- 

 cluded with the element earth. The four elements were types 

 of great classes which together comprised the universe ; in an 

 extended sense they typified solidity, liquidity, and gaseity, while 

 fire represented the force exercising itself upon matter. The 

 function of fire is well signified in the story of Prometheus. 

 Fire was the anima; air, water, and earth together constituted 

 the corpus. A rude classification of this description must of ne- 

 cessity obtain, until, by means of refined methods of observation 

 and a determinate modus of physical thought, minuter differences 

 can be detected and examined, until by various tortures we can 

 force nature to yield up her well- concealed secrets; for, as Francis 

 Bacon has observed, " occulta naturse magis se produnt per vex- 

 ationes artium, quam cum cursu suo meant " f. Let us bear in 

 mind, if we are disposed to harshly criticise the four-element 

 theory, that although instituted in barbaric times and by unlet- 

 tered men, it prevailed universally during the most golden period 

 of ancient philosophic thought, and very generally during the 

 Middle Ages and the succeeding period ; even in the memory of 

 our grandfathers the idea was not utterly subverted. 



II. Of old chemical literature, and of the significance of the terms 

 Sal, Sulphur, Mercurius, as employed by mediaeval Chemists. 



I say the four-element theory obtained very generally during 

 the Middle Ages, because it did not obtain universally; for 

 there had arisen a sect of men who devoted themselves to the 

 study of the intimate nature of matter, and who had elaborated 



* Plato speaks of the various kinds of fire in the Timceus ; and Aristotle 

 has the following passage : — " Ov yap iariv tv elbos tov irvpos' Zrepov yap 

 1<jti T(3 e'ldei av6pa£, Ka\ </>X6|, Ka\ (pas, eKacnov avrav Trvp ov," 



t Novum Organum, lib. i. aph. 98. 



