136 HISTORY OF CHEMISTRY. 



metals from their calces, are analogous, and consist 

 alike in the addition of some combustible element, 

 which Stahl termed phlogiston ((fAoyla-Toi', com- 

 bustible). The experiment most insisted on in the 

 work now spoken of 2 , was the formation of sulphur 

 from sulphate of potass (or of soda) by fusing the 

 salt with an alkali, and throwing in coals to supply 

 phlogiston. This is the " experimentum novum." 

 Though Stahl published an account of this process, 

 he seems almost to have regretted his openness. 

 "He denies not," he says, "that he should per- 

 adventure have dissembled this experiment as the 

 true foundation of the Beccherian assertion con- 

 cerning the nature of sulphur, if he had not been 

 provoked by the pretending arrogance of some of 

 his contemporaries." 



From this time, Stahl's confidence in his theory 

 may be traced becoming more and more settled in 

 his succeeding publications. It is hardly necessary 

 to observe here, that the explanations which his 

 theory gives are easily transformed into those which 

 the more recent theory supplies. According to 

 modern views, the addition of oxygen takes place 

 in the formation of acids and of calces, and in com- 

 bustion, instead of the subtraction of phlogiston. 

 The coal which Stahl supposed to supply the com- 

 bustible in his experiment, does in fact absorb the 

 liberated oxygen. In like manner, when an acid 

 corrodes a metal, and, according to the existing 



2 P. 117. 



I 



