June 10, 2011

Global, 1823: Rhodium Price

In describing the the incidence & difficulty treating Rhodium-Gold, M. Del Rio in Mexico cryptically rebuked another unnamed European scientist & refiner of Rhodium. Apparently, some secretive monopolist had refused to assist a fellow scientist with information to efficiently cupel Rhodium from Gold: a professional discourtesy and minor scandal. 
Dr. Henry Hyde Wollaston seems the most likely target for this tacit accusation. He had discovered the metal (1805); in this period, there's no record of any other scientist working with so much platina residue for Rhodium production. In earlier incidents, Wollaston had been accused of secrecy and opportunism by other chemists; he also only published his platinum refining method (which had been ascertained by others) on his deathbed in 1828.

In the same letter of rebuke, Del Rio contradicts Wollaston by name; furthermore
, a couple of years earlier the English chemist had mutually unsatisfactory dealings with Arago (the Paris publisher for this rebuke) over pricing another PGM product, Auropalladium. In one of his Notebooks, Wollaston mentioned the Frenchman did not pay nor thank him!

Since an English chemist (rather than Breant or any other European Gold assayist) was the purported offender, little wonder the Mexican's professional scorn came to print in a most highly regarded Paris journal. The French and the English: going at it once again.

Reviewing the Rhodium Notebook, Kronberg, Coatsworth & Usselman (1981)* calculated Wollaston had refined 129.5 Troy Ounces in 1819, the largest quantity then known. Presuming Wollaston accurately informed the French and/or Del Rio (for how else would they know the value of his Rhodium) this weight permits an approximate valuation and calculation for a Producer's Cost. Where 1,800 piastres ~ Fr 9,063. - 9,594, and 1 peso = 4s 6d:

1823: 1 Troy Ounce Rhodium (Producer's Cost) = £ 3.13
.... Peso/USD$ 13.90; Fr 70.-74.

It is also highly relevant to note that in 1822-25 Wollaston was just beginning to successfully merchandize his own Rhodium Alloy in a manufactured state, as nibs for "Rhodium Pens." Any other large scale Rhodium production would potentially have jeopardized his own revenue and enterprise. It is also reported he had not been successful selling his Palladium, although other scientists mention a persistent high price for Pd.

1822 - 1825: 1 Troy Oz. Rhodium (Retail) = £ 15.00 (USD$ 72. - 75.)

Wollaston merchandized his Rhodium at ~ 5x higher than his cost.  Rhodium tips were 4:1 Rhodium/Tin, 2 per nib (£ 0.050) @ 0.46 Grain per tip; the pens sold 'trade' for £ 0.20

The initial retail price was likely £ 1. in 1822, falling to £ 0.75 in 1828, then £ 0.50 by the mid-1830s.

See B. I. Kronberg; L. L. Coatsworth; M. C. Usselman: "The Artifact as Historical Document Part 2: The Palladium and Rhodium of W. H. Wollaston." Ambix, 28(1), pp. 20–35 

1825: 1 Troy Ounce Rhodium Tin Alloy (Trade: .80 Rh) = £ 12.
1825: 1 Troy Oz. Rhodium (Trade: .999 Rh) = £ 15.
1825: 1 Troy Oz. Rhodium (Trade: Mfg: .80 Rh) = £ 26.09
1825: 1 Troy Oz. Rhodium (Trade: Mfg: .999 Rh) = £ 32.69

The 1827 German report of the December 1824 Mexican notice indicates that Dr. Wollaston's alloy was only 20-25% Rh (80-75% Au) not pure.

Citation: Annalen der Physik und Chemie, Vol. 10 (1827) p.322

Rhodium-Gold (Au 57% - Au 66%) from Mexico, analyzed c. 1823:

The French published rhodium refining techniques in 1822.

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