The principles of chemistry : illustrated by simple experiments / by Julius Adolph Stöckhardt ; translated by C.H. Peirce.

  • Stöckhardt, Julius Adolph, 1809-1886.
Date:
1851
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Licence: Public Domain Mark

Credit: The principles of chemistry : illustrated by simple experiments / by Julius Adolph Stöckhardt ; translated by C.H. Peirce. 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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    it to the air; the water soon becomes turbid and cov- ered with a film, which gradually grows thicker, and settles at the bottom. If after some days the water has become clear again, it will have lost its alkaline taste; the lime dissolved in it, having been chemically changed by the air and rendered insoluble, will be found as a powder at the bottom of the tumbler. 47. Experiment. — Put into a flask half an ounce of litmus, pour over it three ounces of water, and let it remain in a warm place until the liquid has obtained a dark-blue color. Litmus consists of a blue coloring- matter, which is soluble in water, and is hence taken up by it; it also contains some earthy matter, which is insoluble, and is deposited as a slimy mass. These two _. 0, _. m substances might be sepa- Fig. 21. Fig. 22. ° rated from each other, as in the former experiment, by decantation, but it can be done more readily by filtra- tion. For this purpose, cut a piece of blotting-paper into a circular shape, fold it together twice, and then place this filter into a glass funnel. That the paper and the glass may not come into too close contact, place between them thin pieces of wood or glass; a piece of cord must also be inserted between the funnel and the neck of the flask into which the liquid is to be filtered, to allow an opening for the escape of the air from the flask, as otherwise the fluid could not flow in. The filter, which must never be higher than the top of the funnel, is first moistened with water before the fluid is poured upon it. Blotting-paper consists of fine linen or cotton fibres matted together, between which are 5