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.

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    have lost a portion of its oxygen: and if the receiver be filled with hydrogen or nitrogen, instead of atmospheric air, no chemical change in the metal will take place ; but it will simply be fused and very minutely sub- divided. In order to oxidize wires, a more powerful battery is required than for their fusion ; and the quantities of elec- tricity required are not the same for each metal. The following table is given by Mr. Singer of the charges necessary for the fusion of given lengths of various metals. The oxides were received upon paper or glass fixed at about an eighth of an inch distance from the wire. The length of the wire exploded in each experiment was five inches. Diameter of the wire in parts of an inch. Charge of the Colours of the figures electrometer. ou paper. Gold wire i ISO 18 Purple and brown. Silver wire 135 18 Grey, brown, and green. Platina wire 1 153 13 Grey and light brown. Copper wire 185 12 Green, yellow, and brown. Iron wire 135 12 Light brown. Tin wire 135 11 Yellow and grey. Zinc wire 1 135 17 Dark brown. Lead wire 1 135 10 Brown, blue, and grey. Brass wire I 135 12 Purple and brown. Brass wire is sometimes decomposed by the discharge, the copper and zinc being separated from each other, and appearing in their distinct metallic colours when the explosion is made over a strip of glass. The figures of all the metallic oxides are usually more beautiful when impressed on glass, than paper, but their colours are less permanent. The same electrical agency which affects these com- positions, is also able to restore the oxides to their na- tural states: for this purpose a very simple apparatus is sufficient.