Chap. 37.] [ 243 ] 



CHAP. XXXVII. 



OF INFLAMMABLE SUBSTANCESIX 

 GENERAL. 



Ignition and Combujiion defirted, Acids formed ly the Combufticn of 

 Inflammable Subjlanccs. Flame, how produced. The QbjeSl ef the 

 prefent Inquiry limited.* What Subftances are commonly termed jn- 

 flammable. 



difference between ignition and combuftion 

 was briefly mentioned in the early 'part of this 

 work ; but after what has been advanced concerning 

 the elaftic fluids, ?.nd the nature of acids, the reader 

 will be prepared for a more philofophical view of 

 the fubject. All bodies which can fupport a cer- 

 tain degree of heat, without the deftruclion of their 

 texture, emit light, and this is called ignition j but 

 combuftion or inflammation is a property which be- 

 longs to fuch bodies only as are capable, when placed 

 in proper circumftances, of augmenting their own tem- 

 perature. Simple ignition produces no permanent 

 change in bodies, but combuflion entirely alters the 

 properties of fuch as have undergone that procefs. 

 From being mild and nearly infoluble in water, they 

 become acrid, pungent, and extremely foluble, and are 

 converted into acids, which differ according to the 

 fubftance, by the inflammation of which they were 

 formed. The terms combuftible fubftance and aci- 

 difiable bafis are, therefore, in the French nomencla- 

 ture, fynonymous. 



It has already been remarked, that inflammation 



is the difengagement of the matter of heat or calo- 



ric contained in vital air or oxygenous gas, in con- 



R 2 fequence 



