Letter from the Secretary of the Treasury transmitting a report prepared in obedience to the act : entitled an Act Regulating the Currency of Foreign Coins in the United States, passed April tenth, 1806
U.S. Mint Reports (1809)
Mint Director Robert Patterson's report on the assay of foreign coins. The same text is in the American State Papers, finance (class 3), volume 2, no. 306.
Paul Hybert summary: "An assay of foreign coins, from mint director Robert Patterson to Treasury Secretary Albert Gallatin, who relayed it to Congress."
A transcription is at: http://www.chicagocoinclub.org/lib/us/asp/cl03.finance/v2/n306.html.