The discovery of oxygen, part 1. : experiments / by Joseph Priestley, LL.D. (1775).

  • Priestley, Joseph, 1733-1804.
Date:
1894
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Licence: Public Domain Mark

Credit: The discovery of oxygen, part 1. : experiments / by Joseph Priestley, LL.D. (1775). Source: Wellcome Collection.

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    It is sufficiently evident from these experiments, that dephlogisticated air is produced from all kinds of earth mixed with spirit of nitre, only that a greater quantity of air is produced from some than from others; the advantage in this respect being on the side of the metallic and calcareous earths. I would observe, that this process seems to furnish a pretty accurate test, perhaps the most accurate hitherto known, of the presence of phlogiston in bodies. Perhaps no species of air can be produced without a certain portion of phlogiston; but probably the nitrous acid itself always contains sufficient for the purpose of dephlo- gisticated air. But nitrous air contains so much phlo- giston, that I think it cannot be produced unless the materials themselves contain it in a very considerable degree. Thus I have no doubt but that tvhite arsaiic^ though it may be thought to contain no phlogiston, really does contain a considerable quantity of it whereas, if the air be highly dephlogisticated, I think it may be considered as the most satisfactory proof we are yet acquainted with, that the substance contains no phlo- giston at all. I shall close this section with an account of the extraction of pure air from other substances besides mercurius calcinatus, and red lead, without the addition of spirit of nitre. Of this kind I have only found two substances, viz. sedative salt, and Romani vitriol slightly calcined, which I had from Dr. Higgins ; besides common salt-petre, which is known to contain the acid of nitre in itself. From the two former I extracted air by means of a burning lens in quicksilver. The sedative salt is not very manageable in this pro- cess; but, with some difficulty, I did extract from it a small quantity of air, in which a candle burned as in common air, and which was diminished as much as