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440 INFLAMMABLE SUBSTANCES. Se&. 22?. phlogifta leave behind in the fire, is not, how ever, attended to. SECT. retie, it nearly triples its fpecificfire. The fame change takes pjac.e in the crocus mortis and in iron. This fad is generally true, whatever he the nature of the fubftance; and even the aeriform ones are in the fame cafe; for phlogifticated air has very little fpecific fire: common air has more of it; and de~ phlogifticated air (hews a molt prodigious quantity oi fire. From thefe fads it is clear, that phlogifton and fire are dif- tin£t and incompatible fubftances ; fo that when one enters into the compofition of any body, the other of courfe is expelled from it. Thus metals are calcined in confequence of a double attraaion, by which the metal imparts its phlo gifton to the air, while the air communicates its fire to the metallic calces ; which is further confirmed by the air that is found in metallic calces, whofe increafed weight, by calcination, correfponds to the air, that is expelled from them, by their reduaion to a metallic form. All combuftible bodies are abfolutely in the fame cafe. Theie are fubftances which contain a large quantity of phlogifton in their compofition, but loofely adherent to them. JDephlogifticated air, which is greatly loaded with fpecific fire, has, at the fame time, a ftrong attraaion to phlogifton ; and, in the aa of combuftion, imparts its fire to the com- buflible body, which is confumed, whilft the air becomes phlo gifticated, or loaded with ph.ogfton. Thus we find that f'ul- phur contaminates the air, when burned, by the phlogifton it throws into it, and the produced vitriolic acid, if any, becomes impregnated with the fame. In fome cafes the moft intepfe heat, or fenfible fire, is pro duced in the combuftion ; but in others it is very moderate. This variety generally depends from the quantity and quality of the vapours produced by the combuftion ; whfcn thefe are very inconfiderable, and the reliduum cannot abforb the fire, which is emitted by the air, the remainder is precipitated or diffufed all around, and produces a very fenfible heat. On the contrary, if the vapours are capable of abforbing it, then verv little heat it produced, We know by the moft cer tain
