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



signed his professorship and went to reside in Berlin, where he 

 died in 1734;. Stahl was eminent as the expounder of new views 

 both in medicine and in chemistry ; and it is difficult to say in 

 which science he was considered most to excel by his contempo- 

 raries. He was a very voluminous writer ; the principal works 

 in which he developes the theory of phlogiston are the fol- 

 lowing : — 



Zymotechnia Fundament alls, published in 1697. 



Specimen Becherianum*, published in 1703. 



Fundamenta Chemia, published in 1723. 



Experimenta CCC numero, published in 1731. 



In the Zymotechnia Stahl has roughly sketched out the theory 

 of phlogiston ; in the Specimen Becherianum he has elaborately 

 annoted passages from Becher's Physica Subterranea, and has to 

 a great extent blended the views therein contained with his own. 

 The Fundamenta Chemics is a text-book of phlogistic chemistry, 

 while in the Experimenta CCC numero we have a number of ex- 

 periments in support of the theory, and answers to supposed ob- 

 jections. The diction throughout is most barbarous, the Lati- 

 nity utterly unpolished ; and in the third part of the Fundamenta 

 Chemics Stahl not unfrequently introduces both German and 

 Latin sentences into the same paragraph. The following pas- 

 sage is from the Fundamenta Chemice : — 



" Sonst ist, wie gesaght, das principium <f>\oyt,aTov im phos- 

 phoro, und muss daraus noch die kunst erfunden werden, mix- 

 tiones oleosas pingues, sen mixtiones pinguedinum, per artem 

 zu machen, als oleum weil in ihm das <f>Xoyi<TTov purius zu 

 finden." It was this habit, exercised in a milder form, which 

 caused Becher to speak of his combustible principle as sulphur 

 ardens and sulphur (f>\oyiorrov indiscriminately. 



Stahl followed the ancients in believing in the existence of 

 two kinds of fire— -(a) ordinary visible fire, requiring combustible 

 matter and air for its nutriment, which he calls ignis or flamma, 

 and (/3) the invisible fire (materia ignis or phlogiston) , which be- 

 comes ipse ignis when associated with particles which readily 

 assimilate its motion. 



The materia ignis he conceived to be a very subtle matter, 

 capable of penetrating the most dense substances; it neither 

 burns, nor glows, nor is visible fj it is agitated by an igneous 



* Stahl was excessively verbose in the titles of his works, as elsewhere ; 

 the following may serve as an example : — " Specimen Becherianum sistens 

 fundamenta, documenta, experimenta, quibus principia mixtiones subter- 

 ranean et jnstrumenta naturalia atque artificialia demonstrantur. Ex autoris 

 scriptis, colligendo, corrigendo, connectendo, supplendo concinnatum ex- 

 hibit Georg. Ernestus Stahl, Prof. Publ. Hall, et Acad. Nat. Cur. College 



f Vide Exp. CCC numero, No. 38. 



