Exposition of the atomic theory of chymistry : and the doctrine of definite proportions / by William James Macneven ... ; with an appendix of chymical exercises, by the pupils of the laboratory, &c.

  • MacNeven, William James, 1763-1841.
Date:
1819
Catalogue details

Licence: Public Domain Mark

Credit: Exposition of the atomic theory of chymistry : and the doctrine of definite proportions / by William James Macneven ... ; with an appendix of chymical exercises, by the pupils of the laboratory, &c. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    choice of hydrogen, because it is the lightest of all known bodies. Sir H. Davy embraced it from him, but changed its value; and Mr. Brande, in his Ma- nual of Chymistry, lately published, has likewise adopted the unit and computation of Dalton, but designates the relation of elementary parts by the term proportionals. This choice was not the hap- piest, for hydrogen has disadvantages from which oxigen is free. The weight of an atom of hydro- gen is so small, that if we employ it as our unit, the number representing an atom of some of the metals becomes inconveniently great. Besides, hydrogen enters much less frequently into compounds than oxigen, and, of course, the unit of comparison, when applied to hydrogen, does not nearly so much facilitate calculation as when it is applied to oxigen. Add, that oxigen con- stitutes among elementary bodies a particular class ; and is, as it were, the center round which chymistry turns. It exists in the greater number of inorganic bodies, and, without exception, in all the products of organic nature. For these reasons Berzelius pre- ferred this unit, as most convenient and most agree- able to the scientific views of chymistry. He re- presents it by 100. (2 Th. An. 451.) Dr. Wollaston and professor Thomson, for simi- lar reasons, have both adopted oxigen as the most convenient unit; nor can there be any hesitation in