An Improved Process for Silver riating
Year: 1899

page_text: Date of Application, 11th July, 1899-Accepted, 19th Aug., 1899
An Improved Process for Silver riating,
I, RICHARD FIEDLER, of 57, Birkenstrasse, Berlin, in the Empire of Germany,
Director, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement:-
In the Specification of my Application for Letters Patent No. 6589, dated 27th
March 1899, I have described a method for silvering metals in a cold state, in
which the metal object to be silvered is cleansed at the same time as it receives
its deposit of silver, this being done by removing grease and other impurities
at the same time by rubbing the articles with a cloth or the like, which is impreg-
nated with the silvering solution and also with various dirt and fat absorbent
or solvent ingredients. The mixture used for this purpose and described in the
said specification contains amongst other materials ammonia and cyanide of
potassium. In practice this process is open to the objection that, on the one hand
cyanide of potassium is difficult to obtain and is of a poisonous nature, and
on the other hand the ammonia loses its strength in a very short time not only
in the vessel in which the mixture may be retained, but also when it is being
applied to the surface to be silvered. This results in the mixture becoming
thick and also in the rubbing away of the deposited silver atoms which soon
reduces the silvering effect of the mixture.
The present invention is intended to produce a mixture which may be used
in a similar way but in which there is no ammonia or cyanide of potassium,
these materials being omitted and replaced by other ingredients which absorb
the dirt and fatty matters. This mixture is made as follows:-15 grams. of
nitrate of silver are first dissolved in 50 grams, of water or thereabouts, and to
this solution hydrochloric acid is added drop by drop; a whitish precipitate is
The solution
formed. Hydrochloric acid is added until this precipitate ceases.
is then filtered and the precipitate which remains on the filter is washed with
water. This precipitate is brought into a finely divided state by means of any
suitable apparatus, and to the product so obtained is added 300 to 350 grams.
of cooking salt, 80 to 100 grams. of acetic acid and 350 to 400 grams. of tripoli
The cream-like or
powder; the whole is then worked up in a litre of water.
milky fluid thus obtained is used upon a cloth or the like, with which the metal
articles to be silvered are vigorously rubbed. By this means the fatty matter
and other impurities on the surface of the metal are rubbed away and dissolved
by the ingredients mixed with the silver, so that the silver comes into contact
with the clean metal surface and is deposited thereon as a firm silver coating.
Instead of cooking salt, there may be used with approximately the same result
salt petre and instead of acetic acid, vinegar may be used, also instead of the
tripoli powder, jeweller's rouge or fine emery may be used.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what
I claim is:-
A process for the mechanical plating of metal in a cold state in which the silver

page_text: plating mixture is composed of 15 grams. of nitrate of silver converted into
chloride of silver mixed with 350 to 400 grams, of tripoli powder or jeweller's
rouge or fine emery, with 80 to 100 grams. of acetic acid or vinegar and 300 to
350 grams of cooking salt or salt petre, the whole in 1 litre of water.
Dated this 11th day of July 1899.
HERBERT HADDAN & Co.,
Agents to Applicant, 18, Buckingham Street, Strand, London.