234. 



which they Im- 

 bibed and be- 

 came bright. 



Thefeleftin 

 vitriolic acid a 

 black matter as 

 fieel does. 



Its habitudes 

 were thole of 

 finery cinder. 

 The black mat 

 ter from pure 

 fteel was affect- 

 ed in the fame 

 manner. 



It was therefore 

 finery cinder, 

 and not carbon. 



Bright needles 

 afforded much 

 lefs black mat- 

 ter than watch 

 fprings, of 

 which the fur- 

 face was blued 

 or oxided. 



ON THE CONVERSION OF IRON INTO .St-EE£. 



meafures of it. In confequence of this, from being of a dark 

 colour, they became exceedingly bright; and I concluded 

 that they were now become fteel, though I was not able to 

 afcertain it by a direct experiment. But after diflblving thofe 

 bright filings in diluted vitriolic acid, a quantity of black mat- 

 ter, as after the folution of fteel, remained unaffected* by it* 

 This being heated in inflammable air imbibed a confiderable 

 quantity of it, and then, by means of diluted vitriolic acid, 

 gave inflammable air very copioufly. This black matter had 

 evidently the properties of finery cinder. 



I then diflblved- 200 grains of broken watch /pipings, which 

 are undoubtedly pure fteel, and collected from the folution' 

 three grains of black matter. Heating this in inflammable 

 air, a great proportion of it was imbibed ; and then, by means 

 of the diluted acid, it gave out inflammable air as copioufly as 

 iron or fteel filings would have done. This black matter, 

 therefore, from the folution of fteel was finery cinder, and not 

 carbon, or plumbago. And as iron acquires weight by be- 

 coming finery cinder, and this addition of weight, I think I 

 have proved to be from water, it can hardly be doubted, but 

 that the addition of weight to iron, in being converted into 

 fteel, is from the fame caufe. Indeed, I believe it to be im- 

 poffible to expofe iron to a red heat in circumftances in which 

 there is any poffible accefs of w r ater, or of air, which always 

 contains water, without a partial calcination of it; that is 

 without its becoming fuperficially at leaft finery cinder. 



This was evidently the difference between the refult of the 

 folution of the watch fprings, and that of an equal weight, viz. 

 200 grains of broken polijhed needles, which had not undergone 

 any calcination. For the black matter that remained from the 

 folution of them would not have weighed a quarter of a grain. 

 Giving colour to fteel, which is done to watch fprings, is al- 

 ways a partial calcination of the metal ; and this appears from 

 the preceding experiments to be the converfion of a part of it 

 into finery cinder, which is the reverfe of plumbago ; being, 

 according to the new theory, an oxide in the higheft degree ; 

 whereas if plumbago contain any oxigen, it is in the loweft 

 degree. 



UL.Au 



