The discovery of oxygen : part 2 / Experiments by Carl Wilhelm Scheele (1777).

  • Scheele, Carl Wilhelm, 1742-1786.
Date:
1901
Catalogue details

Licence: In copyright

Credit: The discovery of oxygen : part 2 / Experiments by Carl Wilhelm Scheele (1777). Source: Wellcome Collection.

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    doctrine believe that the air is in itself unalterable; and, with Hales, that it really unites with substances thereby losing its elasticity ; but that it regains its original nature as soon as it is driven out of these by fire or fermen- tation. But since they see that the air so produced is endowed with properties quite different from common air, they conclude, without experimental proofs, that this air has united with foreign materials, and that it must be purified from these admixed foreign particles by agitation and filtration with various liquids. I believe that there would be no hesitation in accepting this opinion, if one could only demonstrate clearly by experiments that a given quantity of air is capable of being completely con- verted into fixed or other kind of air by the admixture of foreign materials ; but since this has not been done, I hope I do not err if I assume as many kinds of air as experiment reveals to me. For when I have collected an elastic fluid, and observe concerning it that its expansive power is increased by heat and diminished by cold, while it still uniformly retains its elastic fluidity, but also discover in it properties and behaviour different from those of common air, then I consider myself justified in believing that this is a peculiar kind of air. I say that air thus collected must retain its elasticity even in the greatest cold, because otherwise an innumerable multitude of varieties of air would have to be assumed, since it is very probable that all substances can be converted by excessive heat into a vapour resembling air. 6. Substances which are subjected to putrefaction or to destruction by means of fire diminish, and at the same time consume, a part of the air ; sometimes it happens that they perceptibly increase the bulk of the air, and sometimes finally that they neither increase nor diminish a given quantity of air—phenomena which are certainly remarkable. Conjectures can here determine nothing