^0 themical Fhilosophy. 



^s to secure for them a general reception. Ac- 

 cording to this celebrated theorist there is only- 

 one substance in nature capable of combustion,^ 

 which, therefore, he cdWed phlogiston ; and all those 

 bodies which can be made to burn contain more 

 or less of it. Combustion is merely the separation 

 of this substance, which, during the process, flies 

 off, leaving the incombustible body with which 

 it was connected behind. He supposed the con- 

 version of sulphur into an acid, by the action of 

 heat, most completely to illustrate and confirm 

 his doctrine; and, indeed, so ingeniously devised, 

 and so extremely plausible were his experiments 

 on this subject, that he was considered as having 

 satisfactorily established, both in the analytic and 

 synthetic methods, the principle for which he con- 

 tended. Objections, it is true, were made to this 

 theory, for it was soon found that sulphur would 

 not burn, if air were completely excluded, and 

 that the sulphuric acid was heavier than the sup-^ 

 posed compound from which it was produced, 

 But still the phlogistic doctrine prevailed. The 

 sim.ple, luminous, and satisfactory manner in which 

 it appeared to account for various phenomena, and 

 the numerous facts which seemed to give it sup- 

 port, aided by the ingenious refinements of its 

 partizans, for a considerable time, bore down all 

 opposition. 



The theory of Stahl maintained its ground for 

 tnore than half a century. It commanded the 

 general assent of chemical philosophers, and was 

 especially adopted and defended by some of the 

 most eminent men which the age produced. And 

 although it is now rejected by a great majority of 

 those who cultivate the science of chemistry; yet 

 neither the ingenuity of the system, nor the talents 

 of its author, can, for a moment, be questioned. 

 Indeed, the doctrine of this great man, though at 



