Mr. G. F. Rodwell on the Theory of Phlogiston. 7 



the physical theory very fancifully and somewhat metaphysically ; 

 it will be observed, however, that the inception of the extension 

 tends to confirm the view expressed above : — 



Sal. 



Sulphur. 



Mercurius. 



Sal commune. 



Sal petrae. 



Sal ammoniacum. 



Acerbum etamarum. 



Dulce. 



Acidus. 



Corpus. 



Anima. 



Spiritus. 



Materia. 



Forma. 



Idea. 



Patiens. 



Agens. 



InformaHS aut moveus. 



Ars. 



Natura. 



Intelligentia. 



Sensus. 



Judicium. 



Intellectus. 



Fixum. 



Inflammabile. 



Vaporosum. 



Vinculum. 



Calidum. 



Humidum nativum. 



Materiale. 



Spirituale. 



Gloriosum. 



The salt, sulphur, and mercury classification, even in its least 

 extended sense, appears somewhat far-fetched ; but I think it is 

 demonstrable that there is a certain appropriateness about it. 

 Salt has in every age been one of the most familiar solids, and 

 on account of its homogeneity and fixity in the fire we can quite 

 understand that it appeared to the old chemists the nearest ap- 

 proach to a pure solid ; hence it was taken as the type of solidity. 

 Sal was more definite and tangible than the broad term terra ; 

 and for obvious reasons neither a metal, nor one kind of rock, 

 nor cultivable earth, could be taken as a type of solidity : in- 

 deed salt was the most elemental definite solid that was then re- 

 cognized, simply because there was no means of revealing its com- 

 pound nature, while the really elemental metals could be appa- 

 rently proved to be compound. Mercury (synonymous with the 

 Greek 'Ep/mfj?) has in every age been the symbol of activity and 

 volatility ; and the chemists had an additional reason for adopt- 

 ing the term, because they traced the origin of their science to 

 the mythical Hermes (or, as they frequently call him, Mercurius) 

 Trismegistus. In some of the old chemical works we find the 

 terms used indiscriminately ; thus " our volatile Hermes " would 

 denote a product of distillation, and be otherwise expressed as 

 "the mercury" of the body distilled. The "sideric mercury" 

 of Paracelsus was supposed to receive its powers from the stars, 

 and to confer fluidity and volatility upon bodies. 



It is, however, to the third element (sulphur) that we must 

 specially direct our attention. Sulphur was peculiarly fitted to 

 be the representative of combustibility ; it was the most abun-= 

 dant readily combustible body known, and from an early age had 

 been intimately connected with the element fire. If we might 

 accept the usual derivation of the word (sal irvp*), it would 

 seem to show that it was regarded as the combustible substance 



* This appears to have been proposed by Isidorus ; vide Vossii EtymolQ? 

 gicon Linguce Latince, 1664, and elsewhere. 



