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
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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.

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    plate-glass will do the same, and the glass-makers have to Toe very careful not to allow large sheets of plate-glass to lie on one another. 3. Heat is an extremely powerful and important form of force. Its influence in chemistry is very extensive, and, like gravity, it will he considered in some detail in the next chapter. 4. Light is a force closely allied to heat, and is also' closely concerned in many of the changes of chemistry. Almost the whole of the light and heat of our globe comes to us directly or indirectly from the suu. 5. Electricity.—Experiment 1.—Take a stick of sealing- wax, rub it briskly with a piece of flannel and hold it near some scraps of paper. They will be attracted by it and will fly upward and adhere to its surface. A tube of glass rubbed with silk will produce the same effect, but the substance called ebonite is more powerful than either. An ebonite comb that has been passed through dry hair will not only attract scraps of paper and small feathers, but in dry weather will emit a crackling sound and a torrent of small sparks, quite visible in a dark room. In all these cases the strange and interesting force called Electricity is set in motion. The “ electrical machine ” is only a plate or cylinder of glass or ebonite, which, by turning a handle, can be made to rub against a> silk cushion covered with amalgam. Electricity produced in this way is called frictional electricity. Another kind of electricity is known, which is called Yoltaic, or Galvanic Electricity. The following experi- ment will illustrate the way in which it is produced. Experiment 2.—Take a tumbler two-thirds full of water, pour into it gradually an ounce and a half by measure of sulphuric acid, and fill the tumbler up with water. The mixture will become very hot, and must be allowed to stand until cold. Take a strip of sheet copper, and another of zinc, not too large to go to the bottom of the tumbler, and high enough to reach to the top. Brighten one of the small ends of each with sand-paper, and solder on each bright patch of copper wire about a foot long. It will improve the experiment very much if you can amalgamate the zinc plate; that is, coat it with mercury