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



world, because it alone of the elements possesses innate motion. 

 Lucretius, who followed Epicurus very closely, asserts that 

 lightning is elemental fire, consisting of smaller atoms than our 

 earthly fire, and hence more subtle and capable of greater pene- 

 tration*. The pure fire was distinguished by various names — 

 among others, "subtilis ignis," " coelestis ignis" " tenuis ignis" as 

 opposed to {i common fire," u mundane fire " "gross earthly fire" 

 &c. From a passage in the ' Ne^eXat ' of Aristophanes, it would 

 appear that the ancients were in the habit of obtaining their 

 " mundane fire " from " celestial fire " by means of a burning- 

 glass f; but the distinction would still seem to exist, for the pure 

 fire would only become visible earthly fire when associated with 

 some combustible substance. According to Seneca, the Egyp- 

 tians somewhat extended the four-element theory by assigning 

 to each element a masculine and feminine, an active and a passive 

 form : thus air was divided into active wind and passive atmo- 

 sphere ; fire into active flame and comparatively passive light J. 

 Aristotle is believed to have been the first to add a fifth ele- 

 ment, more divine than the others — aldrjp. the sether, pervading 

 all things, and in perpetual motion. He asserts that it gives 

 motion to the other elements, and hence derives the term from 

 del and 6eco. The term quinta essentia, afterwards employed by 

 the chemists, originated from this idea of a fifth element. A 

 subtle medium, rarer than air, was admitted in ancient Hindu 

 philosophy; we find it alluded to both in the Sanch'ya and 



* " Perfacile est jam animi ratione exsolvere nobis 

 Quare fuimineus multo penetralior ignis 

 Quam noster, fluat, e tsedis terrestribus ortus. 

 Dicere enim possis ccelestem fulminis ignem 

 Subtilem magis e paruis constare figuris : 

 Atque ideo transire foramina quae nequit ignis 

 Noster hie e lignis ortus, tsedaque creatus." 



De Rerum Natura, lib. ii. 

 •f* STREPSIADES. fjdr) irapa tolctl (papp,a.K07rG)\cus ttjv \L6ov 

 ravrrjv eoopas, ttjp koXtjv, ttjv 8ia(pavrj, 

 a<p' rjs to Trvp anTOvari. ; 

 Socrates. ttjv vakov A eyas ; 



STREPSIADES. eycoye. 

 Socrates. <t>epe, tl brjr av; 



STREPSIADES. ei ravr-qv XajBcov, 



Snore ypdcpoiro ttjv diKrjv 6 ypapparevs, 

 a.TT(£>Tep(o aras a>de npos rbv fjhiov, 

 ra ypd/xpar' eKTrj^aifxi rrjs ip-rjs §1*079." 

 X "iEgyptii quatuor elementa fecere : deinde ex singulis bina marem et 

 feminam. Aerem marem judicant, qua ventus est ; feminam qua nebulosus 

 et iners. Aquam virilem vocant mare ; muliebrem omnem aliam. Ignem 

 vocant masculum qua ardet flamma, et feminam qua lucet innoxius taetu. 

 Terram fortiorem marem vocant, saxa cautesque ; ferninse nomen assignant 

 huic tractabili ad culturam." — Quasi. Natur. lib. iii. cap. 14. 



