VOL. LXXXI.] PHILOSOPHICAL TRANSACTIONS. 4Q 



The heavy inflammable air, he imagines, is produced in this manner. The 

 oxygene of the imperfectly reduced metal combines with the charcoal to form 

 fixed air ; at the same time another portion of charcoal is thrown into an elastic 

 state, that is, into inflammable air, and burns on the surface with a very deep 

 blue flame, on account of the admixture of fixed air. The heat which is so 

 obviously generated in the mass at the beginning of the fermentation, he attri- 

 butes to the combination of the oxygene and charcoal ; a fact which, with 

 several others, shows, if not the falsehood, at least the imperfection, of the 

 modern doctrine on the subject of heat. The acidifying principle, it would 

 appear, has some power of generating heat independent of its condensation. 

 Here abundance of elastic matter is discharged ; yet, notwithstanding the heat 

 absorbed by its formation, and that which flows out of the metal in all directions, 

 the whole mass becomes hotter. The oxygene cannot be supposed to have much 

 specific or latent heat, because it undoubtedly exists in the iron in a very con- 

 densed state. Neither does the appearance of the mass allow him to ascribe 

 this generation of heat to the burning of the inflammable air at the surface, as 

 will also be immediately evident for another reason. The less deep blue colour 

 of the flame at a subsequent period in the operation is probably owing to the 

 absence of fixed air, or at least to its being produced more sparingly, the 

 oxygene being now nearly consumed. It will not appear surprising, that the 

 oxygene in this case should be consumed before the charcoal, if it be considered, 

 1. that grey iron contains a large portion of plumbago ; and, 2. that fixed air 

 contains a much larger quantity of oxygene than of charcoal ; near 3 times as 

 much, according to our best experiments on its formation : so that he ascribes 

 the subsequent fermentation accompanied with the lighter coloured flame almost 

 entirely to the conversion of the charcoal into an elastic fluid. A very experi- 

 enced philosopher has asserted, that water is' necessary to this conversion ; an 

 opinion concerning the justness of which Dr. B. has long entertained great 

 doubts. Whenever he has distilled charcoal per se, he has found the first por- 

 tions of gas to contain fixed air ; an appearance owing, he believes, to the de- 

 composition of v.'ater absorbed from the atmosphere ; but after continuing the 

 process for some time, there has still been a production of inflammable air ; but 

 from this neither lime-water nor milk of lime would absorb any portion, though 

 when fired with vital or common air, it would produce fixed air ; and if mois- 

 ture was added to the charcoal, inflammable and fixed air would be generated 

 anew. It further appears, from the experiments of Dr. Austin and some 

 others, that charcoal consists of the hydrogene and azote of the French chemists. 



Now, during the continuance of the lighter coloured blue flame, the mass 

 shows no power of generating heat within itself; a circumstance which indicates 

 that the heat produced in the former part of the operation does not depend on 

 the burning of the gas at the surface ; and inspection will satisfy any one that it 



VOL. XVII. H 



