February 26, 2015

UK, 1931

Citation: The Mining Magazine, Vol. 45 p.364

Platinum. — Prices continue to advance to counteract the depreciation in sterling, current quotations for refined metal being £11 7s. 6d. to £11 13s. 6d. per oz. Demand, however, is poor. 
Palladium. — Quotations stand at about £4 15s. to £5 per oz. ...

... A fairly good enquiry has developed from users in this country, prices here at £95 for ingots and bars being below the international value of the metal, which remains at £85 gold.

USA, 1936

??/1936: 1 Troy Oz. Platinum (Mkt, Ingot) = USD$ 43.
9/18/1936: 1 Troy Oz. Platinum (Mkt, Ingot) = USD$ 70.

"Platinum prices dropped $6. an ounce to $64. when buyers melted away after the spectacular runup in prices recently.
platinum in small lots — 3 oz. ingots, then ... The Eisemann firm accumulated the metal, went to Handy & Harman, metallurgists, and had them assay the bullion and cut of an inch thick. These plates, euphemistically called ingots, were placed in safekeeping in the Chemical Safe Deposit Co., which issued certificates of deposits. It was these certificates that the brokerage firm merchandised. But International Nickel and other platinum interests did not take kindly to this "interference" with their market. Platinum has not been a hoarding metal — essentially. It has not been used for monetary purposes like gold and silver. Rather, it is functional — largely used in jewelry and in industry. Vogue Not So Strong Supposedly, the higher the price of platinum, the greater the use for rings and watch cases and rare settings — at least that was the case years ago, when nothing but the most expensive was good enough. But today, platinum is not prized purely on a price basis.


Citation: The Literary Digest, Vol. 122, Issues 14-26 11/28/1936 p. 42
PLATINUM: Wall Street's New Trading Certificates Survive Wild Price Gyration Last August, the price of platinum skyrocketed. From a moderate $43 an ounce, it soared to $70 — twice the price of gold. Then, just as precipitately, in September, prices for the white metal plummeted. Last week, the cost was $48 an ounce. Jewelers, who constitute almost half of America's wholesale market for platinum, and the chemical and electrical industries,which... 

The outbreak of war would inflate platinum prices, because the metal is used in detonating devices on bombs. (During the World War, it cost $105 an ounce; later it climbed to $170.) The Eisemann brothers learned about business in their father's ostrich importing company; later, they pioneered in radio manufacturing. With their earnings, they had dabbled in stocks. "Three years before the stock market collapsed in 1929, they reasoned that their merchandising experience had fitted "

Next, they hired Handy and Harman, metal brokers, to assay the platinum bullion, to cut it up into three-ounce plates, an eighth of an inch thick. These plates, dubbed ingots, were placed in the vaults of the Chemical Safe Deposit Co., New York, which issued certificates against them — one certificate for each ingot ... The 10 per cent, "spread" covers a host of costs: 6 per cent, to the broker, commission to buying agents who obtain the bulk platinum, charges for assaying the metal, profits to the Eisemann firm. To obtain his platinum, the certificate holder merely takes or mails his certificate to the Chemical Safe Deposit Co. To dispose of his platinum after getting it, he must shop around for a buyer, perhaps a jeweler or a dentist. The certificate holder may, however, sell his certificate back to the Eisemann Co. at a discount, thus cashing in on his investment without taking possession of the metal. After its launching, however, the Eisemann platinum trading venture promptly ran into difficulties.

Citation: Engineering and Mining Journal, Vol.137 (1936)
"Certain it is that the recent skyrocketing of platinum prices was not due to extraordinary demand in the usual channels of trade. ... platinum convenient and attractive, the brokerage house has acquired a quantity of the metal and cast it into three-ounce ingots of authenticated fineness. These are placed in a safe deposit vault and become the security for negotiable certificates of ownership issued to buyers."

UK, 1942

Citation: The Mining Magazine, Vol.66-67 -(1942) p. 212 

Germany, on the other hand, appears to be getting very short of platinum. Prices remain at £8 10s. to /8 12s. 6d. per ... All available supplies are very readily absorbed, buying prices here ranging from about 55s. to 100s. per unit f.o.b. producing country, according to circumstances. ... but essential needs are bemc met in full, with prices still officially held at £110 per ton delivered for minimum 99% ingots.

UK, 1943

Citation: The Mining Magazine - Vol. 68 (1943) p.108
Platinum. — Prices remain at the level at which they have stood for a long time — namelv, £ 8 10s. to £8 12s. lxl. per troy oz. for ... Whilst official buying prices here still range from 55s. to 100s. per unit f.o.b. producing country most of the material is ... Virgin ingots, minimum 99%, are still priced at £110 per ton delivered.

1943: 1 Troy Ounce Platinum (ore, NSW) = £ 6.3724 (USD$ )
1945: 1 Troy Oz. Platinum (ore) = £ 11. (USD$ )

1925: 1 Troy Oz. Osmiridium (ore, Tasmania) = £ 30.7786 (USD$ )
1925: 1 Troy Oz. Osmiridium (ore, Cited High) = £ 31. (USD$ )

1938: 1 Troy Oz. Osmiridium (ore, Cited Low) = £ 0.7667 (USD$ )
1938: 1 Troy Oz. Gold (Fine, mkt) = £ 8.69 - 9.14 (USD$ )

1940: 1 Troy Oz. Osmiridium (ore, Rise) = £ 25.9542 (USD$ )
1940: 1 Troy Oz. Gold (Fine, mkt) = £ 10.4167 - 10.671 (USD$ )

1945: 1 Troy Oz. Osmiridium (ore, 'High') = £ 25.525 (USD$ )
1945: 1 Troy Oz. Osmiridium (ore, avg.) = £ 24.45 (USD$ )
1945: 1 Troy Oz. Gold (Fine, mkt) = £ 10.6 - 10.74 (USD$ )

Citation: Official Year Book of the Commonwealth of Australia No. 37 - 1946 and 1947 By Australia. Commonwealth Bureau of Census and Statistics. p. 832; p.620

South Africa, 1934

1934: 1 Troy Oz. Platinum (SA Export) = SA £ 6.102753
1935: 1 Troy Oz. Platinum (SA Export) = SA £ 5.7509


UK, 1936

9/18/1936: 1 Troy Ounce Platinum (UK Mkt, Ingot) =  £ 13.50 (USD$ 68.35)

"A remarkable advance in the price of platinum was experienced during 1936 when on September 18, the London quotation for the metal approximated £13 10s. or $68.29 per fine ounce in Canadian funds, later declining to $55.75 by October 3. "Metal and Mineral Markets", New York, commented on the situation in August as follows: "Though the demand for platinum against normal requirements of consumers has increased this year along with the general recovery in business, and prices have strengthened, the recent advance of $10 per ounce in a single day was not welcomed in platinum circles. The sharp advance on August 18 to $53 per ounce resulted chiefly from speculative activities. Literature has been distributed to probable buyers informing them that refined platinum is now available in convenient three ounce bars, properly assayed and stamped by a recognized dealer in the metal as to weight and fineness. The bars, it is stated, may be deposited in a bank and certificates issued against the platinum to facilitate trading. Speculation in platinum by the uninformed, producers fear, will do more harm than good to the industry". During recent years leaf palladium has been used in the same manner as leaf silver and gold ; palladium alloys, chiefly white in color, are utilized largely in the manufacture of jewellery; palladium is also employed as dental metal, as contacts"

"Speculation in platinum metal was initiated in New York early in 1936, when platinum was offered as an alternative to gold for hoarding purposes. The corporation concerned bought the metal and deposited it in a bank in the form of 3-ounce ingots, numbered and stamped for weight and fineness. Certificates were then issued on the backing of the metal held in the bank, and outside speculators dealt in the certificates at prices as much as £2 above the value of the metal. Speculation soon assumed serious proportions and the price of the metal advanced steadily. When the peak price of £14 was reached early in September a number of speculators attempted to take profits, but consumers who were but consumers who were already well supplied refused to buy and the speculative holdings were then offered at declining prices.  A. H. Atkinson and A. R. Raper, both of the Mond Nickel Co., Ltd., gave special attention to the subject of platinum at the autumn meeting of the Institute of Metals, which was held in Paris."

"When the peak price of  £14 was reached early in September, a number of speculators attempted to take their profits. Consumers who were already well supplied, refused to "buy." Speculative holdings have since "been offered at declining prices in order to tempt consumers to purchase. (Consular Clerk Alfred Nutting, London, Oct. 13, 1936.) Messrs, R. E"

February 25, 2015

Canada, 1931

"As a result the price of platinum fell from £22 an ounce in January to £13, 10s. in July. Unsettled conditions continued for nearly four years, so that with some fluctuations, the bottom price of $23 an ounce was reached in May, 1931. On the eighteenth of that month the price was raised to $27.50 and on June 8 to $40 an ounce."

UK, 1930

Citation: Yearbook of the Encyclopedia Americana (193?) p.583
"The fall in the price of platinum in 1930 was attributed to the increased production of South Africa at a price so far below what the metal could be produced for in other sections that it was proposed by producers to form a combination to maintain a stable price, as has been the practice of the diamond producers' syndicate."

In South Africa, the ore price fell to £ 7. (6/1930: USD$ 33.88)

USA, 1934

Citation: Minerals Yearbook (1934) p. 564

"Refiners reported the following prices for platinum in 1934: High $40.50; low $26, and average for the year $34.50 an ounce compared with $44.50,$18.50, and $30.75 an ounce, respectively, for 1933."

USA, 1930

January, 1930: 1 Troy Oz. Pt (NYC Spot, .999 Fine)= USD$ 63.
9/17/1930: 1 Troy Oz. Pt (NYC Spot, .999 Fine)= USD$ 34.

Citation: The Jewelers' Circular - Vol. 102, p.149
THE Department of Commerce has recently released statistics as to platinum and allied metals in 1930 as compiled by Hubert W. Davis in the report of the Bureau of Mines. This report, which will eventually be published as pages 99-112 of the report of "Mineral Resources of the United States, 1930," contains the usual tables and information given out annually by the department covering the production of the platinum group of metals, as well as notes as to the condition of all production of these metals in various countries, particularly the United States, Australia, Canada, Colombia and the Union of South Africa; but no important information as to Russian production or the condition there is given outside of the figures already published in The Jewelers' Circular which are included. ... by consuming industries, in troy ounces On the matter of stocks on hand, the report publishes the following table: Stocks of platinum metals in the hands of refiners in the United States, December 31, 1921-1930, in troy ounces... On the subject of prices, Mr. Davis' report shows the fluctuation during the year which began at $63 an ounce for refined platinum in January the market price was subject to frequent reductions until the price of $34 an ounce was announced on Sept. 17.

1930: 1 Troy Oz. platina (US Ore)= USD$ 40. - 30.
1930: 1 Troy Oz. Pt (US Mkt)= USD$ 45.

Citation: Bureau of Mines Information Circular (1934) p.91
"The price paid in 1930 for domestic crude platinum ranged from $30 to $40 per troy ounce; the average quotation for the refined metal was $45."

According to the United States Bureau of Mines, the platinum refiners of the United States, in 1930, purchased 797 ounces of crude placer platinum of domestic origin and 44,765 ounces of crude platinum from foreign sources...

1930: 1 Troy Oz. Pt (Alaska Spot, .999 Fine)= USD$ 44.

Citation: Geological Survey of Canada, Memoir 243, p.60

Platinum ore from Tulameen was 60.4% , at C$ 35.16/Ozt Fine Pt, C$ 16.97/Ozt Pd, C$ 97./Ozt for Os and Ru, and C$ 43.65/Ozt Rh

Colombia, 1930

c.1930: 1 Troy Ounce platina (Chocó Spot, 86.6% Ore)= $ 65.
c.1930: 1 Troy Oz. Pt (Chocó Spot, .999 Fine)= $ 75.06

Colombian Ore, 86.6%

Colombia, 1966

Actual yield more than 100% higher than official


February 24, 2015

UK, 1966

In 1966, an ultra rarity numismatic item sold at 7.3x the Platinum Spot.

1965-6: 1 Troy Oz. Platinum (Bulk) = $100.

Duvivier Campo-Formio Medallion:
Diameter 3.5 cm 
Weight: 2.50 Ozt, 77.76 g.


Weight: 2.35 Ozt, 73.1 g.

Citation: Catalogue of the First Portion of Greek, Roman, and Foreign Medieval Coins and medals collected during the last 50 years by the late Thomas Thomas Esq., Sotheby & Co. Auction 7/8/1845

"a recent sale at Christie's (23 July 1965 or 1 March, 1966) , when Lord Margadale sold the coins and medals collected by his grandfather, Alfred Morrison, there is no less interest in commemorative medals of the past. Fig.3 for instance, a platinum medal dated the year 6 of the Revolution showing Napoleon as General-in-Chief of the army in Italy and commemorating the peace in that year, made £ 650. {USD$ 233. - 231.73} The artist is Duvivier. The reverse, the mounted conqueror crowned with a laurel wreath by, I presume, Victory, is no doubt banal enough in its severe neo-classic manner; it is interesting though, that, according to the inscription, it is not the nation which is expressing its thanks, but "Les Sciences et Les Arts Reconnaissants..."

7/24/1965-3/1/1966: 1 Troy Oz. Platinum (Numismatic Rarity) = $ 725.45 - 729.29

February 7, 2015

Colombia, 1882

Resrepo (1886) assumes the Colombian Gold Yield, converted from 21/24 to .999, should be be C$ 21.032/Ozt.  Therefore, 122,995 Ozt./3,825.6 Kg @ C$676.20 in Fine Gold.
1882: Colombian Gold Yield, .999:  146,375 Ozt., USD$ 21.03/Ozt

1882: Colombian Gold Yield, .9167:  186,500 Ozt., USD$ 20.675/Ozt

Citation: Consular Reports: Commerce, manufactures, etc, Vol. 24, Issues 85-87

US statisticians estimated Colombia produced 186,538.6 Ozt Fine Gold in 1882, presumably an error (not factoring fineness as stated by the Colombia source.)

Citation: Congressional Serial Set (1886) "XXVI Worlds Production of Gold & Silver" p.256

February 6, 2015

Mexico, 1878

In 1877-8, Mexico (re-)exported 24.09 Kilograms = 774.51 Ozt. platina ore for M$ 2,505.88: per Kilogram (32.15 Ozt) M$ 104. (C$ 95.68)

1877/8: 1 Troy Ounce platina (Ore, imported) = M$ 3.2355 (USD$ 3.23)
1877/8: 1 Ozt. Pt (~75% Ore, imp.@ .999) ~ M$ 4.31 (USD$ 4.31) 

1877-8: Platina (re-)export to USA, 

Germany, 1879

1879: 1 Troy Oz. Platinum (Mfg, Bulk) = 27.99 (USD$ 6.68)

Citation: Die Chemische Industrie, 1892 Vol. 15 (1892) p.70

February 5, 2015

France, Platinum Louis d'Or: 1801 - 183?

The Double Louis officially weighed 15.297 g. (236 English Grains Troy, 1.376 m.) @.900 Fine, 212.46 grains Fine Gold.

Citation: Traité des monnaies d'or et d'argent qui circulent chez les différents peuples...; Pierre-Frédéric Bonneville


c.1844: 236 grains =15.293 g.; 212.3 grains = 13.757 g. Fine Gold

Citation: Bankers' Magazine, Journal of the Money Market..., Vol. 1-2 (1845)

c.1834: Actual Circulated Coin 232 grains =15.03 g.; ~209 grains = 13.528 g. Fine Gold

In ~45 years, the standard Double Louis in circulation lost 4.1 grains.

Although finer examples weigh 15.29, this Double-Louis dated 1786 reportedly weighed 15.31 g. (236.27 grains), showing wear. 

Platinum Counterfeit, without gilding: stated as 15.13 g. (0.48644 Ozt) Diameter: 28.5 mm

Counterfeit Double Louis Gold Coins (c. "1787"):
{After December 1801} To start a new job, {Louis} Sénot bought {Francois}Roy two lots or forty-two marcs platina ore, which he gave to {Pierre-Joseph} Brasseur. At the latter's abode, they formed planchets, which were struck at Passy, and produced 350 Double Louis.  In March thru June 1802, {Aubin} Quartier sold them to Vigie,who passed on to Dumont and Poulareau.

Citation: Recueil des causes célèbres, et des arrêts qui les ont décidées, Vol. 4, Door Maurice Méjan

Where the Paris Marc (0.24475 Kg) = 7.86889533 Ozt., 42 Marcs = 10.28 Kg or ~330.5 Ozt.
Assuming Abraham L. Breuget purchased and re-sold better quality platina, 75% Pt purity, 42 Marcs should have produced ~248 Ozt Fine Pt. ; 80% Pt produced ~278 Ozt.

In Gold-alloy, 350 Double-Louis weighed true at ~172.1 Ozt, with 155. Ozt Fine Au.  However, 1801 manufactured counterfeits of 14+ year old (1788) coins should have appeared neither suspiciously new nor full weight; average weight for 350 1788 Double Louis might be 170.64 Ozt, ~153.6 Ozt. 

The first stage of the operation (refining) appears grossly inefficient, unless the platina was of exceedingly very poor grade (~47% Pt.) Alternately, ~60 - 76 Ozt otherwise remained or 'disappeared' (sold as scrap to market, unaccounted for in the criminal report.) Another theory makes sense: Sénot agreed to refine the platina for Breuget, providing the Paris watch-maker with about half the Fine Platinum (~143 Ozt, or 9 Livres) at no cost a month or so later. 

The coins were discounted at least 10.42% below nominal value and perhaps significantly below market value for true Double-Louis at the time. 

Unknown, the cost of the platina and the expense for the manufacture of blanks would establish the profitability of the enterprise.

If 330.5 Ozt platina ~ 155 Ozt = Fr. 15,050 - 16,800,

By reasonable timeline, 

In 5-6 months, three counterfeiters refined and produced 350 Platinum-Gold coins. 
1 coin per day? 

Paris Counterfeiters purchase massive quantities: ~2,408 Ozt total: at 70% Pt ~ 1,685 Ozt. 

QUARTIER purchased an additional 300 Marcs from England, plus 6 Marcs from Janetty (late 1802?) at unknown price.


282 Single Louis d'or = ~62.44 Ozt Pt

"These pieces are made of platinum covered with gold, of which they contain three francs worth at the very best." 

Fine Gold = 0.86 g., 13.3 Grains

1801: 1 Troy Ounce Platinum (Coined, Counterfeit Fr.) = Fr. 97.084 - 108.3725

Les premiers faux double Louis de 48 livres en platine doré seront découverts dans un atelier clandestin de la Creuse fin 1804. Pourtant, un autre rapport du 4 avril 1805, indique que les premières fausses monnaies en platine semblent être des Louis de 24 livres, fabriqués par un certain Miot et par un Orfèvre de Troyes nommé Guérin. (?)

The first dual fake Louis 48 pounds in gold plate will be discovered in a sweatshop Creuse end of 1804. Yet another report of April 4, 1805, indicates that the first fake currencies platinum seem to be Louis 24 books, produced by a Miot and a goldsmith named Troyes Guerin. (?)  

See also:
Numismatique & Change, "Mystère autour du faux double louis en platine 1787 BB" : 65 (43), 70 (24). 

Platine. 15,11 g. 28,5 mm.

This copy is a fake Double Louis in gilded platinum, see note 117) F. Droulers in his Encyclopédie, tome III, p.149 and an article of the same Numismatique et Change in October 2000 that indicate these Double Louis would have been made during the Restoration. The same author had already studied these fake Louis in platinum from Strasbourg and Orleans in Numismatique et Change of July 1978 et dans le BSFN of January 1979. Technically, the striking of counterfeits could only have  occurred only from the Empire Period. Errors are detected, the date in 1787 when Strasbourg was closed; as for Orléans the workshop was not allowed to strike gold and the different use on counterfeits only appeared in 1788. This beautiful specimen is struck with edges made very property. Even wear indicates average circulation. Interesting example. 

1009. ROYALE FRANCE , Louis XVI (1774-1793), Double Louis d'or with bare head, BB 1787, Strasbourg. Contemporary counterfeit in gilded Platinum. Right: Bare head left, long hair. Different: heart (Jean-Louis Beyerle). Reverse: Multiple ecus of France and Navarre under a crown. Different: Toothed Edge (John Guerin). Ref .: Dupl 1706 var.; Ci, 2182 var.; Gad. 363; Dr., 614 (listed only 6 copies). 15,27 g. Extremely Rare. Flawed planchet and the assayer's test on the edge.

Counterfeit Double Louis "1788" (but produced at an unknown date):

Where the 1785-91 Double Louis weighed 15.2970 Grams with a Specific Gravity ~18.7, the False Double Louis should have had a Specific Gravity of ~15.35. 

The False Double Louis had ~ 4 Grams .999 Au and 11.2 Grams .98 Pt. Silver was presumably some part of the solder, an unknown alloy. Aqua regia would rapidly dissolve Copper and and because the dissolution had a greenish tint, Copper was quite possibly omitted from the analysis, in error.

Factoring alloy-solder (90% Au, 8.34% Cu, 16.67% Ag) with Fine Gold, it seems about 1.5 grains Troy were lost and the full solder weight should have been 1.21 Grams: about 7.8% of the circulated counterfeit's absolute weight. Deducting also the Platinum planchet (11.2 g), the Fine Gold gilding (shell) then appears to have been 3 g.

Two problems arise: what was the presumed loss of Copper, and what was the 'wear rate' (to calculate the original total weight) ?

Assuming the Double Louis should weigh 15.297 at full Mint weight new, and a constant wear-rate, the ordinary Double Louis in 1835 weighing 15.25 g had lost 1.5 mg or ~0.02315 Grain Troy per 5 years.  Assuming the rarity of an intact counterfeit implied a circulation rate half the norm, full weight of the counterfeit may have been as high as 15.471 g.

Given the gilding weight remaining, the intact shell should have weighed 3.3%, in the correct alloy proportion with French coin in 1788. (Copper Loss: 0.3 g.)  

The coin was 0.13 cm thick and the circumference was 7.288 cm, so the 'area of the circumference' (approximate value of the edge) was 0.94744 cm2.  The diameter was unstated but correct at 23.2 mm, so the area was 5.3824 cm2 per face.  The entire surface should have 11.715 cm2 of Fine Gold, factoring minor wear. 


Les faux double louis sur lesquels nous avons expérimenté nous ont été remis par un changeur du Palais-Royal qui désirait connaître quelle était la proportion exacte d'or qu'ils contenaient. 

Ces faux louis, au millésime de 1788, paraissent avoir été fabriqués avec une lame de platine plaquée d'or sur ses deux faces , et qui aurait été ensuite frappée. Leur épaisseur était de 0,0013 ; leur densité à +10 = 20.135.
Leur poids absolu était un peu plus fort que celui des double-louis ordinaires , car un de ces faux louis pesait 15.450, au lieu de 15.250 que pèse le double louis ordinaire. 
Un de ces faux louis , brisé en quatre morceaux , a été traité à l'aide d'une douce chaleur, par un mélange de trois parties d'acide hydrochlorique et d'une partie d'acide nitrique étendu du quart de son poids d'eau; au bout de dix minutes environ, tout l'or qui était à la surface des morceaux de platine avait été dissous; on a décanté la liqueur, qui avait une belle couleur jaune orangé, et on a lavé à l'eau distillée les morceaux de platine, qui avaient alors une belle couleur blanche argentine et portaient encore l'empreinte des reliefs qui existaient sur la pièce.
La dissolution a été étendue d'eau pour recueillir un précipité blanc floconneux qui s'y était formé parle refroidissement. Ce précipité a été reconnu pour du chlorure d'argent qu'on a aisément réduit au chalumeau avec un peu de carbonate de soude. Le globule d'argent obtenu et séparé de la scorie pesait = 0,201.
Après avoir séparé le chlorure d'argent, on a projeté peu à peu dans la dissolution du protosulfute de fer pulvérisé jusqu'à ce que la liqueur cessât de se troubler, il s'est formé un précipité brun verdâtre d'or très-divisé qui a été recueilli par décantation, lavé d'abord à l'eau acidulée par l'acide hydrochlorique et ensuite à l'eau chaude; ce précipité d'or, séché et calciné au rouge, a pris la couleur de l'or mat; son poids était de 4,050.
La petite quantité de platine qui a été dissoute en même temps que l'or par l'eau régale, a été isolée en concentrant la liqueur d'où ce dernier métal avait été précipité, et en y ajoutant une solution saturée d'hydrochlorate d'ammoniaque. Le précipité d'hydrochlorate de platine et d'ammoniaque recueilli et lavé à l'eau alcoolisée a fourni par la calcination 0,56 de mousse de platine qu'on a réunie aux morceaux de platine restés insolubles dans l'eau régale.

Il résulte des essais entrepris sur ces faux doublelouif, qu'ils sont formés de:

La petite quantité d'argent que contiennent ces fausses pièces de monnaie a-t-elle été introduite pour souder l'or au platine? ou bien existait-elle dans l'or qu'on a employé pour les fabriquer? C'est ce qu'il n'est pas possible de décider positivement; cependant, comme on n'a trouvé aucun autre métal servant d'intermède comme on n'a trouvé aucun autre métal servant d'intermède à l'union de ces deux métaux, nous serions assez disposé à admettre la première hypothèse.
J. S. Lassaigne

The fake Double Louis on which we have experimented were given to us by a Palais-Royal money changer who wanted to know the exact proportion of gold they contained. 

These fake Louis, dated to 1788, appear to have been made of a platinum lamina heavily plated with gold on both sides which was then struck. Their thickness was 1.3 mm; density at +10 = 20.135.

Their total weight was a bit heavier than the ordinary Double Louis, because one of those fake Louis weighed 15.450 instead of 15.250, the weight of a typical Double Louis.

One of these fake Louis, broken into four pieces, was treated with a gentle heat, with a mixture of three parts hydrochloric acid and nitric acid portion extended a quarter of its weight water; after about ten minutes, all the gold that had been on the of the surface of the platinum pieces had been dissolved; the liquid was decanted, which had a strong orange-yellow color, and the platinum pieces, after washing with distilled water, then had a fine silver-white color which still bore the relief imprints of that had existed on the coin.

Dissolution had been diluted with water to collect a flaky white precipitate which had formed on the so-called cooling. This precipitate was recognized for Silver Chloride that was easily reduced by blowtorch with a small amount of Sodium Carbonate. The globule of silver obtained and separated from the slag weighed = 0.201 g.

After having separated the Silver Chloride, powdered iron protosulfute was gradually added to the liquification until the liquid stopped bubbling, a greenish-brown precipitate of finely divided gold formed which was collected by decantation, washed first with water acidified by hydrochloric acid and then and then by hot water; this gold precipitate, dried and calcined to a red heat, took the color of dull gold; its weight was 4.050 g.

The small amount of Platinum which had been dissolved together with the Gold by aqua regia was isolated by concentrating the liquid in which the latter metal was precipitated by adding a saturated solution of Ammonia Hydrochlorate. The precipitate of Platinum Hydrochlorate and Muriate of Ammonia was collected and washed in alcoholic water, allowed for the calcination of 0.56 g. of Platinum sponge joined to the remaining pieces of Platinum insoluble in aqua regia.

The result of the tests undertaken on these fake Double Louis produce:
Gold ...................  4.050 g.
Silver .................   0.201 g.
Platinum ........... 11.200 g.
                               15.451 g.              

Was the small amount of Silver that these counterfeit coins contain introduced to solder the gold to the platinum? Or did it come from the gold that used to make them? That's what it is not possible to decide positively; however, as we found no other metal serving as an intermediary to the union of these two metals, we would be quite willing to admit the first hypothesis.

Jean-Louis Lassaigne (had worked in the laboratory under Louis Nicolas Vauquelin, by the early 1830s a leading chemist in Paris.)

Citation: Journal de chimie médicale, de pharmacie et de toxicologie..., Vol. 1 (1835)

Of the "Trésor de Calavados" discovered in Caen, 1997 a false Louis (Gold gilded Platinum) weighed 7.64 g.