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Essential Fire Assay Terms



as used in Bibliography





Inquartation. – When the bead contains too little silver to part, it is necessary to alloy it with more silver. This process is called inquartation. It originated from the custom of the old assayers of adding silver until the gold was one-quarter of the whole. They considered a ratio of 3 parts of silver to 1 of gold to be necessary for parting. At present, in assaying gold bullion, a ratio of only 2 or 2¼ parts of silver to 1 of gold is used, mainly to avoid all danger of the gold breaking up in the boiling acid.

In this case some little silver remains undissolved, even though the alloy is rolled out to about 0.01" in thickness. (p. 121)


Many assayers, when working for both gold and silver and suspecting an ore to be deficient in silver, add silver to the crucible or to the lead button before cupeling, part directly and then run separate assays to determine the silver in the ore. (p. 122)


Inquartation. – The method of separating the gold from the silver in gold-silver alloys by boiling with nitric acid does not act equally well in all cases. An alloy half silver half gold, rolled to thin sheet and boiled for half an hour with nitric acid, may still retain more than two-thirds of its silver. An alloy of 1 part gold and 1.7 parts of silver gives up practically the whole of its silver under similar treatment. The gold is left in a coherent, though easily broken, sheet retaining the shape of the original alloy. The gold thus left is quite spongy and porous, so that the acid can penetrate into its innermost portions. But if the silver is in large excess in the alloy, the removal of the silver is less complete, and the residual gold, instead of holding together in a form easy to manipulate, falls to a powder which requires care and time in its treatment. The older assayers, therefore, added silver to their gold in such proportion that the alloy for parting should be one quarter gold to three quarters silver. This operation they called inquartation.

The modern practice is to aim at getting an alloy with 2.5 parts of silver and 1 part of gold. In gold bullion assays this proportion should be obtained with fair exactness. And in the parting of such gold buttons as are obtained in assaying ores it is well to aim at this proportion, though absolute precision is not a matter of importance.


The silver used for inquartation must, of course, be free from gold and is best prepared by the assayer who is to use it.   .... It should not be in long strips or angular pieces likely to perforate the lead in which it is folded. When wrapped in the lead it should be in the middle and should make as compact a parcel as possible.


Inquartation. – In order to ensure complete parting without breaking up of the gold, assay beads containing too little silver must be inquarted with additional silver. Usually a total of four or five times as much silver as gold is required, except when masses of 200 mg or more of gold are to be parted, as in the gold-bullion assay, when the ratio of silver to gold is 2:1 or 3:1. Early assayers believed that the best alloy for parting contained one-fourth gold and three-fourths silver. In fact the literal translation of the Latin word for parting, quartatio, is "fourthing". (p. 75)


Proof silver used for inquartation is sometimes stamped into discs of convenient size and weight or drawn into flat wire and pieces of the required weight cut off with gauged pliers. Some assayers consider it more convenient for weighing out to granulate the silver and use only the granules that will pass through a sieve of about 13-mesh (p. 264)





Parting is the separation of silver from gold by means of acid. In gold assaying nitric acid is almost exclusively used, although sulphuric acid is usually employed for parting large lots of bullion. Nitric acid cannot be used successfully to separate silver from gold unless there is present at least three times as much silver as gold (p 118).


The idea of parting is to so manipulate that the gold will, if possible, remain in one piece.

The nitric acid for parting must be free from hydrochloric acid and chlorine in order to have no solvent action on the gold and also because any chlorides present would precipitate insoluble silver chloride on the gold. The acid strength is of great importance and the proper strength to be used depends upon the composition of the alloy. The higher the ratio of silver in the alloy, the less the acid strength should be.

Great care is necessary in parting to avoid breaking up the gold and subsequently losing some of the small particles, as well as to insure complete solution of the silver. (p. 118)

"Touchstone""Touch Needle"     Also ►  Wächli & Vuilleumier articles



Waarborg Holland

Assaying with the touchstone

The touchstone testing method is a fast non-destructive screening and assaying method. The kind of precious metal and the fineness are determined by testing the colour and chemical resistance. The materials used are touchstones, touch acids and touch needles (alloys with an accurately established fineness of precious metal).

The advantage of the touchstone testing method is that in principle every parts of the article can be tested.


A rubbing of the item is made on a special stone, treated with acids and the resulting color compared to references. Differences in precious metal content as small as 10 to 20 parts per thousand can often be established with confidence by the test. It is not indicated for use with white gold, for example, since the color variation among white gold alloys is almost unperceivable.

Jordi de
Sant Jordi

+ 1390's
† 1424

"Lo Canviador"

["The  Banker"]

 33 Mas, pus le tochs dels metals fer sabets
 34 prou destrament, que·s autre be no us say,
 35 e·z avets fayt dels bons lo
bon assay,
 36 e com etz tals que·l millor no·n triets,
 37 no us pensets vos que us ho dia per me,
 38 qu’aicest traüt no us vull far, per ma fe.
 39 Ja no metrets vostres diners menuts           (tornada)
 40 ab  mos florins de pes ben coneguts.

 33 But given that you know the touch of the metals how to make
 34 skilfully enough, that I don't know if there is anything you can do so well,
 35 and you have made the best amongst the
good assays,
 36 why is it that the best you didn't choose ?
 37 don't imagine that I ask you this for me,
 38 that in this nuisance I do not want you to meddle, for my faith.
 39 No longer shall you mix your little pennies                                (refrain)
 40 together with my florins of weight well known










cupellation /

Kupellation /

cupellatie /

coupellation /

coppellazione /

copelación /

купелирование / микро(~) /

капельный метод

hallmark (-ing)


waarmerk / keur

poinçon de l’État

punzonatura /
bollatura, bollo


пуансон / пробирное клеймо

touchstone /
touchstone test

Probierstein /

toetssteen /

pierre de
touche, touchau

pietra di

piedra de toque /
prueba de toque

пробирный камень / проба на пробирном камне



Fire Assay



(free download)


Articles from Word Gold Council (WGC)

◊ Assaying of Gold Jewellery - Review of Methods for Measuring Gold Content

◊ Gold Analysis - Comparisons of available Techniques

Articles from  ►"Gold Technology"  Magazine (WGC)

◊ "Assaying of Gold Jewel. - Choice of Technique" (GT, nº 32, 2001)        Dr. C. W. Corti

◊ "Analysis of Carat Gold"                         (GT, nº 22, Jul. 1997)                                M. Brill

◊ "Assaying and Hallmarking in London" (GT, nº 3, Jan 1991)                       D. W. Evans

◊ "Assaying Gold in Switzerland"               (GT, nº 3, Jan 1991)         Wälchi / Vuilleumier

◊ "Touchstone Testing of Precious Metals" (GT, nº 3, Jan 1991)       Wälchi / Vuilleumier

Articles from ►"Gold Bulletin" Journal (WGC)

◊ "Analysis of Gold. A Review of Methods"      (GB, Vol. 13, issue 1)      Roland S. Young

Articles from the ►"Alchemist" Journal , (LBMA)

◊ "The Art & Science of a Precious Metal Lab."   (Alch., nº 48, LBMA)              David Court

Articles from "Pure & Applied Chemistry" Magazine"

◊ "Analytical Chemistry of Noble Metals" (Pure & Appl. Chem., Vol. 49) Dr. Jon Cl. van Loon