New-York tribune., 1902-08-17

WHAT HALLMARKS" MEAN
METHODS BY WHICH PURITY OF GOLD
AND SILVER ARE TESTED.

silver chain knows what the hallmarks are
like, but few, says The Birmingham Post" have
a clear idea as to whence they came and what
they mean. Many people imagine that "ster-
ling" or standard" article is made Of pure sold
or silver. but as a matter of fact 1t is necessary
to mix with the precious metal certain proper
ton of harder metal before it be worked
into articles of commerce. This fact would
open the way to very easy and profitable frauds
if the law did not make special provisions for
the protection Of the purchaser Of gold or silver
plate The first statute for this purpose was
enacted more than five hundred years ago, and
the main principles then laid down are adopted
in most of the modern assay acts, viz that all
gold and silver goods shall be equal to certain
standards, and shall not be offered for sale
until assayed and marked by the wardens Of
the craft An important act was passed in the
reign of Richard II, and as our old law makers
were not so verbose as their successors, 1t may
be quoted verbatim in a few lines: Because
gold and silver which is wrought BY goIdsnltns
in England is oftentmes less fine than it ought
to be- because the goldsmiths are their own
Judges, be it ordained that henceforth every
goldsmith puts his own mark upon his work,
and the assay of the Touch belongs to the
mayors and governors of the cities and bOr-
oughs with the aid of the Master Of the Mint
if there be such. putting the mark Of the clIy
or borough where the assay is The duty here
assigned to the mayors and governors has de-
voIved upon the gOldsmiths companies, anu
they have delegated it to the officials Of the as
say offices. of which there are now four in Eng
land. two in Scotland and one in ireland.
OF these institutions Birmingham has by far
the largest. In spite OF what me may say as
to its ancient constitution, the Birmingham As-
say Office leads the way in improving the proc
ess Of assay. The esta tabIishment Of an assay
office in birmingham was largely due TO me
efforts of Matthew BoulJon ttre versatile part
ner of James WatD. who Was one Of the cAIeI
promoters of the act of 1913. There are thirty
six guardians of whom nine are representatives.
of the trade the rest being public men of such
varied types as Lord Norton and the Right Hon
Joseph Chamberlain They are appointed for
life and elect the wardens. of hom there are
at present five.
There are two alternative methods for trying
silver. and two consecutive operations for test
ing gold In olden times both metals were as
sayed by simply rubbing the plate with
piece of hard. black and smooth stone, ana
wetting the touched places with the tongue 50
as TO bring to light the various tints which diS-
tinSuish one quality OF precious metal from an
other This rough and ready method Is SUN
used for certain purposes. but the touchs'ohe
IeaNeS too much TO the Judgment OF the Opel''N9A
To fulfil the requirements of the Assay Ollce'
The process at present recognized by Ia" u
known a the dry way to distinguish 1t from
the wet way" So far it goes, the NIS
method is used for both silver and gold IAe
lead covered pill of precious metal IS piaceu -
small cupeI of calcined bone, and heated over
a gas fire in air furnace of an improved pat
tern, designed by Arthur Westwood- "HeH
all the silver has been dissolved the pure gu
left in the platinum cupeI is 50 brittle thi' i
has to be annealed before it can BE- weIgheu "
tell how much silver has been extracted 1foii -
By comparing the weight of the pure goId "''N
the original five grains You get the propo1'
of gold to alloy in the manufactured artlcle-
This new process is much quicker anu s''V
than the cupeIation which has been eXplal'eU'
and it is gradually supersedins that metno".
certain weight of the silver 10 be asS@SVr
dissolved in nitric acid by heat, and soIu''or.
of iron and salt are added by means o' my
graduated pipettes. Common salt can NC =
but suIpho-cyanide is more effective -
known that a certain quantity OF SAT- SoiO'
will precipftate a certain quantity OF sANe.
fore acting on the iron. Consequently Il
liquid is not discolored by the iron IL IL
dent that the glass vessel contains the SUM
ard quantity Cor more) of silver Thus ''' =
sayer has only to compare the sample IL -
ton with one prepared from standard S--'0i'
and he can see a 4 glance whether II -
or below the standard. by adding Hl,''s =,
quantities of salt OF silver solution be ca" "
how much above or below standard the "''