Useful Information for the Trade.
Silversmith's Alloy.
Copper, 1 oz.; nickel, 3 dwts. 12 grs; bismuth, 6 grs.; zinc, 2 dwts.
12 grs.; soft iron, 12 grs.; tin, 12 grs. This compound is said to
form a fusible and malleable metal, that can be easily worked by the
silversmith; it is also said to resist oxidation through atmospheric
influences.
Silver Wares.
Never scratch-brush silver ware with a solution of soap and water;
neither should it be washed with the solution if it can be avoided, as
it gives it the colour of pewter; better to scratch in weak ale, or if
plain, rub it with a piece of wash-leather and prepared chalk.
Cleaning Plate.
Carbonate of ammonia, 1 oz.; water, 4 oz.; Paris white, 16 oz.; well
mix the ingredients together, and apply to the surface of the plate by
means of a piece of soft leather or sponge.
Imitation Silver.
Fine silver, 6 dwts.; nickel, 6 dwts.; copper, 8 dwts. This alloy will
cost about 1_s._ 9_d._ per ounce.
Another Recipe.
Fine silver, 5 dwts.; nickel, 6 dwts.; copper, 9 dwts. Cost about 1_s._
6_d._ per ounce.
Removing Gold from Silver Articles.
Silver articles which have been gilt, may be brought back to their
original colour, by simply covering them with a thick solution of
borax, and then well annealing them. After this process if the articles
are boiled for a short time in one of the whitening mixtures and
scratched, they will present a beautiful white and uniform surface.
Oxidizing Silver.
A beautiful deep black colour, possessing great lustre, may be given
to finished silver work by boiling it in the following preparation
for some time:--Bromine, 5 grs.; bromide of potassium, 5 dwts.;
water, 10 oz. The boiling should be effected in a stoneware pipkin,
and generally from two to five minutes will suffice for the purpose.
The work is finished after the proper colour has been attained, by
well rubbing with a soft piece of wash-leather and a little best
jeweller's rouge. It is better to make the work as bright as possible
before submitting it to this mixture; for this reason it is preferable
to thoroughly buff all plain surfaces on a piece of felt by the
application of the lathe, as by that means a characteristic brightness
is imparted.
Dipping Mixture.
Brass or metal goods may be cleaned and their oxides removed by
dipping into the undermentioned liquid for a few seconds only:--Oil of
vitriol, five parts; water, five parts; nitric acid, two and a half
parts; spirits of salts, two drachms. Well mix the several ingredients
together, and immerse the work in the solution cold. The mixture
improves after a quantity of work has been dipped into it.
Silver Powder for Copper.
Chloride of silver, two parts; cream-of-tartar, two parts; alum, one
part. Mix with water to the consistence of a paste, and apply with a
soft leather or sponge; when sufficiently whitened, well polish.
Powder for Silver.
Chloride of silver, 1 oz.; sal ammoniac, 2 oz.; sandiver, 2 oz.; white
vitriol, 2 oz.; bichloride of mercury, 5 dwts. Make into a paste with
water and rub the articles over with it; then expose them to a good
heat upon a clear fire, in order to run the silver and evaporate the
mercury, after which process dip in very weak sulphuric acid to clean.
To Protect the Polish of Metals.
Melt one part by weight of best wax paraffin and when sufficiently
cooled, add three parts of petroleum. Well mix together, and apply to
the polished articles by means of a soft brush. The protecting film is
required to be only very thin, therefore too much should not be put on.
Silver Stripping Mixture.
Sulphuric acid, six parts; nitric acid, one part. Take a large
black-lead crucible or pipkin, and heat the mixture in it; when this is
done, put in the work required to be stripped, occasionally withdrawing
it to ascertain the progress made. The large proportion of sulphuric
acid allows of the dissolution of the silver, and does not sensibly
corrode or interfere with copper, or any of its alloys, if kept quite
free from water; therefore be careful not to introduce wet articles
into the mixture. After finally withdrawing the work, it should be well
rinsed, annealed, and then boiled out.
Stripping Silver.
Put some strong oil of vitriol in a similar vessel to those above
described, apply heat, and during the process add a few crystals of
saltpetre. When the solution has become hot enough the work should
be immersed in it, and be moved about or agitated until the silver
is dissolved from the surface. The articles should not be allowed to
remain too long in the solution, and if it does not remove the silver
quickly, more saltpetre should be added from time to time until the
desired end be attained.
Soft Solder.
Pure tin, two parts; lead, one part. Melt and well incorporate
together; when this is done pour into strips for use.
Soldering Fluid.
Muriatic acid (spirits of salts), three parts; metallic zinc, one
part; or as much as the acid will take up. When dissolved and all
effervescence ceases, allow it to settle, then decant the clear
solution from the sediment at the bottom of the vessel in which it
has been made, and it is ready for use. If a small quantity of water
be added to the mixture at this stage, say one-sixth, it will answer
quite as well for some purposes. For soldering iron and steel, a very
small portion of sal ammoniac is of great advantage to the mixture for
promoting toughness.
_Dissolving fine silver._--Nitric acid, two parts; water, one part.
_Dissolving silver alloys._--Nitric acid, one part; water, two
parts.
_Dissolving copper._--Nitric acid, one part; water, four parts.
_Dissolving soft solder._--Perchloride of iron, one part; water,
four parts.
_Dissolving silver solder._--Nitric acid one part; water four parts.
_Dissolving sealing-wax._--Place for a time in a solution of
spirits of wine.
Resist Varnish.
Dissolve resin, or copal, in essence of turpentine, or boiled linseed
oil; to give it different shades of colour, add red lead, chrome
yellow, or Prussian blue.
Plate Powder.
Whitening, two parts, white oxide of tin, one part, calcined hartshorn,
one part. Reduce to a powder and well mix together; apply as usual.
Electro-plating Soft Solder.
Take nitric acid, 1 oz.; water, 2 oz.; copper about 1 oz. in small
flat pieces; when the copper has all dissolved and effervescence has
ceased, the solution is ready for use. To apply it, take up a few
drops by means of a camel-hair pencil and apply it to the desired
part, then touch it with a bright piece of steel, and there will be
instantaneously a film of copper deposited. If the copper has not
spread all over the desired part, the process should be repeated, when
deposition in the plating bath will take place with perfect success.
Another Recipe.
Take sulphate of copper (that which accumulates in the whitening
mixture), one ounce; water, six ounces. Reduce the sulphate of copper
to a fine powder and dissolve it in the water. Treat according to the
directions given in the previous one. A good mixture for effecting the
same result may be made by dissolving verdigris in vinegar.
Testing Silver Wares.
Take nitric acid, six ounces; water, two ounces; bichromate of potash,
one ounce. Reduce the salt of potash to a powder and well mix it
with the acid and water. The solution is used cold, and should be
placed in a stoppered glass bottle, the stopper having a long dropper
extending into the mixture, which acts as the agent for conveying the
liquid from the bottle to the article to be tested. The surface of
the article should be perfectly clean, and to make certain what kind
of metallic substance you are testing, it is advisable to rub a file
over some obscure part of the surface and to apply the liquid to that
part. The test liquid should be used, by means of the glass stopper,
to the filed part, and immediately removed by a sponge damped with
cold water. If the article consists of pure silver, there will appear
a clean blood-red mark, which is less deep and lively in proportion to
the quality of the metal. Upon platinum the test liquid has no action
whatever; on German silver at first a brown mark appears, but this is
removed by the sponge and cold water; on Britannia metal a black mark
is produced; and on all the various metals an entirely different result
takes place to that on silver; therefore the test is a simple one,
and may be advantageously employed for the detection of any fraud in
relation to the precious metal.
Another Test.
Water, 2 oz.; sulphuric acid, 2 drs.; chromate of potash, 4 dwts. This
mixture is applied in the same way as before and produces a purple
colour of various depths, according to the quality of the silver. No
other metallic element exhibits the same colour with this preparation.
Perchloride of Iron.
Take spirits of salts, 8 oz.; crocus powder (jeweller's polishing
material), 1 oz.; well mix them together and keep in solution. In
preparing the mixture for the dissolution of soft solder, &c., take 1
oz. of it, and add to it 4 ozs. of boiling water.
Aluminium Alloy.
Copper, 18 dwts; aluminium, 2 dwts.
New Alloy.
Zinc, 19 dwts; soft iron, 1 dwt. This alloy is said by the inventor to
be remarkable for its whiteness and tenacity.
Removing Gold from Silver Wares.
Sometimes the process of annealing and boiling-out fails to effect the
removal of the gold from articles which have been thickly gilt, in
which case the work should be submitted to the action of the following
chemical preparation:--Sulphuric acid, 6 ozs.; muriatic acid, 1 oz.;
nitric acid, 1/2 oz. This mixture should be heated in a black-lead
crucible or earthen vessel, and the work immersed until the dissolution
of the gold takes place, carefully watching it during the progress of
the operation. The gold may also be removed by using a strong solution
of oil of vitriol, to which has been added a fair proportion of common
salt.
Silver Plating Fluid.
Nitrate of silver, 1 oz.; cyanide of potassium, 2 ozs.; water, 12 ozs.
Put the cyanide and the nitrate of silver into the water; shake them
well together until they become thoroughly dissolved, then let the
mixture stand till it becomes thoroughly clear. It is then ready for
use. If preferred, a little prepared chalk may be used as an additional
ingredient.
Plate-cleaning Powder.
Take of the finest rouge, and prepared chalk, equal parts, well mix and
use dry by means of soft leather.
Solder for Aluminium.
Spelter, 18 dwts.; aluminium, 1 dwt. 6 grs.; copper, 18 grs. To be
employed for soldering the _pure_ white metal, and not the so-called
aluminum bronze, that being commonly soldered with bath-metal solder.