302 Expmments and Inferences refpefling 



as obferved in the combuftion of charcoal, the proportion in the combuftion of diamond was 

 17,88 of carbone, and 82,12 of oxygen. 



The learned reporter proceeds to ofFer his remarks upon the theory of thefe fadls. Though 

 he could not doubt the facSs, he, at firft, felt a degree of repugnance to admit fo confiderable 

 a difference in this cotnbuliible and charcoal, the latter of which contains little more than half 

 the quantity of oxidable matter, which is capable of being burned at a temperature prodigi- 

 oufly below that which is required by the diamond. But, upon reflexion, he foon obferved 

 that this is not the firft example of acidifiable bafe, the firft degree of oxidation of which 

 is effefted with extreme difficulty, though the fubfequent acidification is very eafy. 2. That 

 many fubftances of the fame genus, likewife, prefent thefe two charatSters ; namely, a greater 

 abundance of true carbone, accompanied with a greater refiftance to inflammation. On 

 thefe heads, he remarks how difficult it is to form a commencement of union of azote and 

 oxygen in the direct way, and the high temperature it requires; whereas nitrous gas cannot be 

 brought in contact with oxygen, without immediately paffing to the acid fiate. Charcoal will 

 therefore be, with regard to the carbonic acid^ what nitrous gas is to the nitric acid ; and 

 the diamond will be to charcoal, what azote is to nitrous gas. It will not, therefore, appear 

 furprizing that more oxygen is required to combine with a fubftance which has yet none of 

 that principle, than with a fubftance which has taken up the quantity which is neceffary for 

 its firft point of faturation. 



The fecond confideration refts on fails no lefs conclufive. Plumbago is a carbonic com- 

 buftible which does not burn at a very elevated temperature, or in nitre in fufion. It pro- 

 duces carbonic acid, and, like the diamond, is richer in combuftible than charcoal itfelf. The 

 incombuftible coal, which was dcfcribed by Guyton in the Dijon Memoirs for 1783, is a 

 fubftance of the fame kind, as is alfo the anthracolite ; and the celebrated Klaproth has like- 

 wife eftablifhed by experiments, that a foffil defcribed by Widenmaa, under the name of 

 incombuftible coal, is of the fame nature. The Kilkenny coal, defcribed by Kirwan as 

 poffeffing the metallic brilliancy, and refufing to burn, unlefs in a ftate of ignition, is alfo 

 capable of decompofing 9,6 of nitre. All thefe are confidered as true oxides of carbone, 

 which, like charcoal, poflefs the property of conducing the eledric fluid, of cementing iron, 

 of depriving certain acidifiable bafes of oxigen, but are not fufficiently oxided to exert this 

 divellent affinity at a low temperature. 



No good account has yet been given, why certain animal and vegetable matters afford 

 coals of fuch difficult incineration ? Why charred pit-coal, known by the name of coke, 

 though half burned in its preparation, is neverthelefs fo powerful in combuftion ? Why turf, 

 the weakeft of all fuel, acquires, by a good carbonization, the property of welding laige 

 pieces of iron better than charcoal .' and why, laftly, charcoal itfelf, after expofure to very 

 ftrong fire in a veffcl impenetrable to the air, becomes to a certain point incombuftible ? 

 The anfwer to all thefe queftions is referred, by our author, to the theory he has developed ; 

 that thefe are all carbones at the firft degree of oxidation, having been deprived of part of 

 their oxygen by the elevated temperature to which they have been expofed. Hence he con- 

 cludes, 



