1826/7: US textbooks did not mention the Russian platina discovery of 1824
In the USA, Platinum was no longer scarce by late 1827. Also, news from Cartagena reached New York in five weeks.
In October 1827, a The Christian Advocate of Philadelphia reported news of large masses of Ural platina. This accurately presupposes the falling price of the (formerly) rare commodity; implicit to "the first instance" comment is that Platinum was still sold at a high price in New York in late 1827.
Citation: The Christian Advocate, Vol. 5 (Oct. 1827) ; Ashbel Green
The Boston Medical Intelligencer (November, 1827) advertised "platina in wire & grains" from Samuel N. Brewer & Brothers, Druggists & Chemists at 90-92 Washington Street, Boston.
Gold premium, 1827:
New York to Liverpool: 25 days, +3 days to London
Liverpool to New York: 45 days, +3 days from London