Transactions of the Linnean Society (Volume 18 (1838-41))

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1798 Excerpt: ...that fire has been the cause.-A 3 Carbon is known to be one of the grand principles of vegetables, andtalso as that 'which is the most fixed, excepting the small portion of the earths contained in them. As a fixed principle, carbon appears to form, in great measure, the vegetable fibre; and after a certain degree of combustion, (by which the other principles have' been disiipated, ) it remains, and the particles of it keep the same arrangement which they possefl'ed'when the vegetable was complete. If, however, the combustion has been carried on with the' free access of air, the carbon enters into combination with oxygen and caloric, and forms carbonic acid. YVe have many examples in which carbon is formed or rather Liberated from those substances with which it was combined in vegetables; and these are now explained as effects (irnilar to those of combufeion. although fire has' not been the cause. In both cases the carbon has been freed from the more volatile principles 3 and under circumstances not favourable to the union of.car.bon with oxygen, the former must necessarily remain more or less undiminished. During the combustion of vegetable matter, the more volatile principles contained in the vegetable fibre (which with carbon also kbrm the resinous and other fimilar subslzances) appear to be first separated; and in proportion to this separation, the other more fixed substance, -which rwe, ca.ll.carbon, is.developed. Thus, by the-progress of combuflion, wood becomes brown..and afterwards black; so that the state of the wood shews the degree of combuslzion to which it has been subjefited, or, in other words, how far the separation of the other principles from.ca.r-bon has been effeetcd., Combuftion is therefore a species of analyfis by-which the principles of ...