Experimental chemistry : founded on the work of Dr. Julius Adolph Stöckhardt. A handbook for the study of the science by simple experiments / by C.W. Heaton.

  • Heaton, C. W. (Charles William), -1893.
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: Experimental chemistry : founded on the work of Dr. Julius Adolph Stöckhardt. A handbook for the study of the science by simple experiments / by C.W. Heaton. Source: Wellcome Collection.

    39/478 (page 13)
    platinum wires pass through the sides of a glass and terminate inside in flat plates (stout platinum wires hammered flat at the ends do very well). The holes in the glass can easily be made by a bradawl filed to a square point and constantly moistened with a mixture of turpentine and camphor, and the wires may bo cemented in the holes with sealing-wax. The glass is filled with water to which a drop or two of sulphuric acid has been added, and over each of the plates a test tube filled with the same acidulated water is inverted. The two ends of the wires are now connected with the poles of the battery. In an instant bubbles of gas rise from the two plates into the test tubes. The gas which comes from the pole connected with the zinc is called hydrogen, that from the other oxygen ; and it will be observed that the volume of the former is twice as great as of the latter. When a little gas has been collected, the mouths of the tubes may be closed with the thumb, the tubes removed, and the gas examined with a taper in the manner described under their respective names. This is the most important instance of the production of chemical energy at the expense of electricity that we possess. Electricity disappears during the experiment, but the hydrogen and oxygen which are produced are able, as we shall find hereafter, to exert an enormous force when they once more combine together. Lastly, let us study the forces which are called into existence during the exertion and consequent disappear- ance of chemical energy. We have, in point of fact, just been considering one of the most interesting cases of this kind in the voltaic battery. In the battery, the electricity which is called into being proceeds directly from, and is proportionate in amount to, the chemical energy which is destroyed in the cell. The zinc is constantly being dissolved by the sulphuric acid, and the force which is thereby exerted immediately takes the new form of electricity. From this electricity we can, as we have seen, produce heat, light, and finally, chemical force, so that we can ultimately recover the very same form of force that we lost in the battery. One of Faraday’s Fig. 1.