Volume 1

A system of chemistry / by Thomas Thomson.

  • Thomas Thomson
Date:
1802
Catalogue details

Licence: Public Domain Mark

Credit: A system of chemistry / by Thomas Thomson. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    64/532 page 46
    Book I. How puri- fied. CMiverted ly combus- tion into carbonic acid gas. Composi- tion of char- coal. den have shown, that this happens only when the char- coal is hot: cold charcoal, they found, absorbed atmo- spheric air unaltered. Common charcoal obtained by burning wood is not quite pure ; but the impurities may be carried off by reducing it to powder, washing it repeatedly with pure water, and then drying it by means of a strong heat in close vessels. When charcoal is heated to the temperature of 370° *, it takes fire, and, provided it has been previously freed from the earths and salts which it generally' contains, it burns without leaving any residuum. ]f this com- bustion be performed in close vessels filled with oxy- gen gas instead of common air, part of the charcoal and oxygen disappears, and in its room is found a particular gas exactly equal to it in weight. Tliis gas has the properties of an acid, and has been called carbonic acid gas. Mr Lavoiftier, to whom we are in- debted for this discovery, ascertained, by a number of very accurate experiments, that this gas is composed of about 28 parts of charcoal and 72 of oxygen f, Lavoisier supposed pure charcoal to be a simple substance, and for that reason invented the term car- bon to distinguish it. But other philosophers were of opinion, that charcoal is a compound body, and that it is composed of carbon and oxygen. The truth of this opinion, which, as far as I know, was first main- tained by Dr Bancroft 1, has been lately established by the experiments of Mr Guyton-Morveau. The diamond is a precious stone, which has been * Morveau, Encyc. Method, art. AJftnitc. X Philosophy of Permanent Colourt, i. 48. f Metn. far. I781, p. 448.
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