THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JANUARY 1868. 



I. On the Theory of Phlogiston. 

 By George Farrer Rod well, F.C.S.* 



I. Of the " subtilis ignis " of the Ancients. — II. Of old chemical literature, 

 and of the significance of the terms Sal, Sulphur, Mercurius, as em- 

 ployed by mediaeval Chemists. — III. Of the supposed nature of fire prior 

 to the rise of the theory of Phlogiston ; specially of Descartes's materia 

 calestis, and of Hooke's theory of combustion. — IV. Of the ideas re- 

 garding the calcination of metals which prevailed prior to the rise of the 

 theory of Phlogiston. — V. Of Becher and Stahl, and of the rise and 

 development of the theory of Phlogiston. — VI. Of the syncretistic nature 

 of the theory of Phlogiston. 



THE theory which proposed to trace the cause of various 

 phenomena of chemical change to the absorption or rejec- 

 tion of " materia aut principium ignis, non ipse ignis," (commonly 

 called the theory of Phlogiston), although much talked of, is, I 

 venture to assert, but imperfectly understood in its entirety. It 

 is valued because it was adopted by many notoriously eminent 

 chemists of the last century ; it is applauded because the phlo- 

 gistians elaborated it into a comprehensive system, and in so 

 doing paved the way for our modern science; it is respected 

 because we are taught to believe that it was the first chemical 

 theory, and the more ardent theorizers of our day point to it 

 triumphantly as an example of the good which may be effected 

 even by a false and chimerical theory. I have endeavoured in 

 the following pages to show to what extent we are justified in 

 our present estimate of the theory. 



* Communicated by the Author. 

 Phil. Mag. S. 4. Vol. 35. No. 234. Jan. 1868. B 



