At the latter place he published in the papers an account of the discovery of a body of the black oxide of manganese, on the banks of the Great Sandy River of Kentucky, and watched the return papers from the old Atlantic States, to see whether notices of this kind would be copied and approved.

Finding this test favorable, he felt encouraged in his mineralogical researches.

Having descended the Ohio to its mouth one thousand miles, by its involutions below Pittsburgh, and entered the _Mississippi_, he urged his way up the strong and turbid channel of the latter, in barges, by slow stages of five or six miles a day, to St.Louis.This slowness of travel gave him an opportunity of exploring on foot the whole of the Missouri shore, so noted, from early Spanish and French days, for its mines.

After visiting the mounds of Illinois, he recrossed the Mississippi into the mineral district of Missouri.

Making Potosi the centre of his survey and the deposit of his collections, he executed a thorough examination of that district, where he found some seventy mines scattered over a large surface of the public domain, which yielded, at the utmost, by a very desultory process, about three millions of pounds of lead annually.
Having explored this region very minutely, he wished to ascertain its geological connection with the Ozark and other highland ranges, which spread at the foot of the Rocky Mountains, and he planned an exploratory expedition into that region.