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



tile parts. Boyle had suggested that, in these operations of fire, 

 the substance acted upon is modified and altered by the fire 

 itself, and that the product of distillation or calcination does 

 not exist as such in the substance distilled or calcined ; he had 

 further suggested that calcination was due to the absorption of 

 " igneous particles." Descartes had for the first time recognized 

 and defined the action of a rapidly moving sethereal medium in 

 effecting changes in matter, and had made fire a product of its 

 action. The experiments of Rey and of Mayow, and Hookers 

 theory of combustion were forgotten or misunderstood, or were 

 considered unassimilable with chemical phenomena in general. 

 Putting all these facts together, the nature of the process of 

 evolution which terminated in the theory of phlogiston has, I , 

 trust, been intelligibly demonstrated. 



The theory of phlogiston was essentially and completely a 

 syncretistic theory. It was built up of idola theatri* collected 

 from various sources ; and these were cemented together by the 

 particular idola specus^oi Becher and Stahl. In this process of 

 syncretism the merit of these men lay ; their fault was a too 

 hasty generalization. In that stage of chemistry syncretism was 

 inevitable ; indeed all theories are more or less tinctured by it, 

 with the exception of those which emanate from a new mode of 

 experimenting, such, for example, as Kirchhoff's theory of the 

 constitution of the sun. But take any theory unsupported by 

 direct experiment (our own atomic theory for instance), and ob- 

 serve how perfectly syncretistic it has been in every stage of its 

 development. Originating at a very early period in India, and 

 there receiving extensive development at the hands of Kanada, 

 the atomic theory passed into Greece, and was adopted and ex- 

 tended by Leucippus, Democritus, and Epicurus ; later it found 

 supporters among the Romans ; and it frequently crops up from 

 the rugged surface of mediaeval philosophy as some one of the 

 greater thinkers of the period made it the basis of, or gave it 

 prominence in, his physical system. Descartes thoroughly 

 adopted it, and extended some of the ancient dogmas until the 

 most diverse phenomena were explained by it ; and thus it en- 

 dured, often adopted, and as often modified, until, as the last 

 process of the syncretism, Dalton applied it to chemistry. Thus 

 step by step we cross great eras in the development of thought ; 



* " Sunt denique idola quae immigrarunt in animos hominum ex diversis 

 dogmatibus philosopbiarum, ac etiara ex perversis legibus demonstrationum; 

 quae idola theatri nominamus." — Novum Organum, lib. i. aph. 44. 



t "Idola specus sunt idola bominis individui. Habet enira unusquisque 

 (praeter aberrationes naturae humanae in genere) specum sive cavernam 

 quandam individuara, quae lumen naturae frangit et comimpit."— Novum 

 Organum, lib. i. aph. 42. 



