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

  • Priestley, Joseph, 1733-1804.
Date:
1901
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Licence: In copyright

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

    49/64 (page 45)
    nitre, by dissolving the iron, would be very apt to deprave the air; and accordingly, in repeating this experiment some time afterwards, I got air that extinguished a candle. I was much puzzled, at that time, to account for the very different results of what was, to appearance, the same experiment; but I do not wonder at' it now. I imagine that, in the former case, the air was produced very rapidly, and therefore that there was not time for the spirit of nitre to act upon the iron; and consequently the salt-petre gave its natural produce : whereas, in the latter case, a mixture of nitrous air (produced by the solution of iron in the nitrous acid, disengaged from the salt-petre) had thoroughly depraved the air. I advance this with the more certainty, as I have found that salt- petre, heated in a glass-vessel, yields very pure dephlo- gisticated air; its own earth, and the spirit of nitre which it contains, being capable, by heat, of forming that kind of union of those two principles which the constitution of that air requires ; and this, I think, is a pretty remarkable circumstance. It may be worth while to observe, that I began my experiments upon nitre in quicksilver; but that the air produced in this manner was nitrous, occasioned by the solution of the quicksilver, as in the former case, by the solution of the iron in the spirit of nitre disengaged in the operation. A copious white fume issued from the nitre in the course of this experiment, like that which attends the rapid production of nitrous air from metals. When I had recourse to my tall glass-vessels (fig. d.) I used an ounce of salt-petre pounded; and filling the vessel up to the mouth with pounded flint, I took the produce of air at nine times, each about three quarters of an ounce-measure. The first produce was not quite so good as common air, the second was of the same