France, 1807

By von Humboldt's mis-estimation, the Paris Price (trade?) was only ~3.5x higher than the Chocó Spott-Preis.  In all probability, the Chocó Spot was likely much lower (~S$ 3./libra) so the Paris multiple was closer to 8.7x higher, though major French consumers (bulk discount) certainly paid far less than his cited trade-price in Paris.

We can probably date von Humboldt's ms. to 1808-09, several years after his return to France (1804.)  The livre refers the Spanish libra, 460 g., whereas the livre poids de marc or livre de Paris was heavier, 489.5 grams (15.74 ozt.)  He did not mean a 'kilogram' (carefully specified elsewhere in this early volume) for that would halve the Paris Price, inconsistently.

Where the Poid de Marc (16 once) was 15.7378 English Troy Ounces; 
1 P.d.M. @ Fr 8./once = Fr 130., @ Fr 9./once = Fr. 150.

Reduced to 1 Spanish Libra, @ Fr 8./once = Fr 122.21, @ Fr 9./once = Fr. 141.
Reduced to 1 Pound Avoirdupois, @ Fr 8./once = Fr 120.5, @ Fr 9./once = Fr. 139.
Increased to 1 Kilogram @ Fr 8./once = Fr 265.6, @ Fr 9./once = Fr 306.5

In S$ @ Fr 8./Once, 1 Libra = S$ 24.5, 1 Pound = S$ 24.1, 1 kg = S$ 53.1
In S$ @ Fr 9./Once, 1 Libra = S$ 28.2, 1 Pound = S$ 27.8, 1 kg = S$ 61.3
 

c.1805?: 1 Troy Ounce platina (Paris mkt, retail) = Fr 9.38  
c. 1809?: 1 Troy Oz. platina (Paris mkt, retail) = Fr 8.13

Citation: Bibliothèque britannique, ou, Recueil extrait des ouvrages ..., Vol. 46 (1811)

Citation: Political essay on the kingdom of New-Spain, Vol. 3  ; Alexander von Humboldt, John Black

European Low Price for platina, might suggest a Colombian platina Low (c.1806)?

In 1807, 46 kgs (1,479 Ozt) of platina were imported to France from the Netherlands.

Citation: Dictionnaire des productions de la nature et de l'art qui font l'objet du ...Magnien p.379