Lectures on electricity / by James Ferguson, F.R.S.

  • James Ferguson
Date:
1825
Catalogue details

Licence: Public Domain Mark

Credit: Lectures on electricity / by James Ferguson, F.R.S. Source: Wellcome Collection.

    103/112 page 97
    EXPERIMENT VI. Place in a glass tube some oxide of tin, so that when the tube is laid horizontally, the oxide may cover about half an inch of its lower internal surface. Place the tube on the table of the universal discharger, and introduce the pointed wires into its opposite ends, so that the por- tion of oxide may remain between them. Pass several strong charges in succession through the tube, replacing the oxide, should it be disturbed by the explosions. If the charges are sufficiently powerful, a part of the tube will soon become stained with metallic tin, which has been revived by the action of the transmitted electricity. Other metallic oxides may be revived in the same way : Vermillion, which consists of sulphur and mercury, will be decomposed with much facility : the charge of a very moderate sized jar being sufficient to separate the mercury. Various fluids are decomposed by the electric spark. Water is resolved into oxygen and hydrogen, in the pro- portion of two measures of the latter to one of the for- mer. The experiment was first made by a society of Dutch chemists, assisted by Mr. Cuthbertson : as then performed it was very laborious and tedious, but it has been much facilitated by an arrangement of Dr. Wol- laston’s. Two very fine wires of gold and platina are inserted into capillary tubes ; and the glass is softened by heat until it adheres to the point and covers it. The glass is then ground away, until the point of wire be- comes visible through a microscope. A series of sparks, being passed under water between two wires prepared in this manner, a series of minute bubbles arise from the points of the wires which may be collected in a small inverted receiver, and afterwards exploded: it is to be observed, however, that a considerable length of time is necessary in order to produce a sufficient quan-
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