Elements of chemistry, in two volumes / by John Murray.

  • Murray, John.
Date:
1828
Catalogue details

Licence: Public Domain Mark

Credit: Elements of chemistry, in two volumes / by John Murray. Source: Wellcome Collection.

    41/768 (page 29)
    for its peculiar qualities, and particularly for its great le- vity, a quality in which it differs so remarkably from me- tals, and which may be supposed to arise from the pre- sence of hydrogen. A similar view may be extended to sodium, and perhaps to the metallic products from the earths *. * This opinion, advanced by Dr Murray, that potassium is a compound of the real metallic base of potash with hydrogen, is one highly interesting, as tending to explain one of the most anomalous facts in chemistry,—the contrast presented by potassium and its ana- logous metalloids to the metals in some of their properties, while they agree with them in so many other characters. It may per- haps be objected to this view, that no such quantity of hydrogen has ever been distinctly proved to exist in potassium, nor has ever been obtained from it. But, as has been remarked by Mr Faraday, in his examination of the compounds of carbon, iodine, and hydro- gen, the atomic weight of hydrogen is so small, that when the equi- valent of the other substance is large, (and that of potassium is not less than 40,) it is very difficult to detect or disprove the existence of one proportional of hydrogen in such compounds. However, in Dr Thomson’s late valuable treatise, (First Princ. i. p. 255) results are stated, as obtained by Gay-Lussac and Thenard, and by him- self, which are strongly in favour of Dr Murray’s view. From the combinations into which potash enters, its atomic weight can he determined with perfect certainty ; it is 48 ; hence, if we deduct 8 from this, being an equivalent of oxygen, there will remain 40, which must be the precise atomic weight of the real metallic base of potash. But the experiments of the French chemists, in which water was decomposed by potassium, gave for the atomic weight of that body, in reference to hydrogen as unity, the number 40.968, which is exceedingly near 41. Now, as an atom of hydrogen is equal to 1, this is a strong presumption that potassium is not the real radical, but consists of one atom of it, 40, and one atom of hydrogen, 1. Dr Thomson states, that his results were similar to those of Gay-Lussac and Thenard, the quantity of hydrogen evol-