Side-Flash.
A bright flashing lateral discharge from a conductor conveying a current
due to a static discharge.
Sighted Position.
In an absolute electrometer (see Electrometer, Absolute) the position of
the balanced arm carrying the movable disc or plate, when the disc and
guard plate are in one plane. The cross-hair on the lever-end is then
seen midway between two stops, or some other equivalent position is
reached which is discerned by sighting through a magnifying glass or
telescope.
Silver.
A metal; one of the elements; symbol Ag.; atomic weight, 108; valency, 1;
equivalent, 108; specific gravity, 10.5. It is a conductor of electricity.
Relative resistance, annealed, 1.0
Specific Resistance, annealed, at 0° C. (32° F.) 1.504 microhms.
Resistance of a wire at 0° C. (32° F.), Annealed. Hard Drawn.
(a) 1 foot long, weighing 1 grain, .2190 ohms .2389 ohms.
(b) 1 foot long, 1/1000 inch thick, 9.048 " 9.826 "
(c) 1 meter long, weighing 1 gram, .1527 " .1662 "
(d) 1 meter long, 1 millimeter thick, .01916 " .02080 "
Resistance annealed of a 1-inch cube, at 0° C. (32°F.) .5921 microhms.
Percentage increase in resistance per degree C.
(1.8 F.) at about 20° C. (68° F.), annealed, 0.377 per cent.
Electro-chemical equivalent, (Hydrogen = .0105) .1134 mgs.
Silver Bath.
A solution of a salt of silver for deposition in the electroplating
process.
The following is a typical formula:
Water, 10.0 parts by weight.
Potassium Cyanide, 5 " "
Metallic Silver, 2.5 " "
The silver is first dissolved as nitrate and converted into cyanide and
added in that form, or for 2.5 parts metallic silver we may read:
Silver cyanide, 3 parts by weight.
While many other formulas have been published the above is
representative of the majority. Other solvents for the silver than
potassium cyanide have been suggested, such as sodium hyposulphite, but
the cyanide solution remains the standard.
Silver Stripping Bath.
Various baths are used to remove silver from old electroplated articles.
Their composition depends upon the base on which the metal is deposited.
Silvered iron articles are placed as anodes in a solution of 1 part
potassium cyanide in 20 parts of water. As kathode a silver anode or a
copper one lightly oiled may be used. From the latter the silver easily
rubs off. For copper articles a mixture of fuming sulphuric acid and
nitric acid (40º Beaumé) may be used. The presence of any water in this
mixture will bring about the solution of the copper. Or fuming sulphuric
acid may be heated to between 300º and 400º F., some pinches of dry
pulverized potassium nitrate may be thrown in and the articles at once
dipped. These methods effect the solution of the silver, leaving the
copper unattacked.