Which preposition to use with sartain

of Occurrences 5%

"And you think that is the craft which was built at New Bedford, and fitted out on the Vineyard?" "Sartain of it, sir; for I know the figure-head, and all about her build.

as Occurrences 3%

"Sartain as ear.

in Occurrences 1%

Studied under Mrs. T. A. Janvier, Adolf van der Weilen, and William Sartain in Philadelphia; under Robert-Fleury, Bouguereau, and Benjamin-Constant, in Paris.

Which preposition to use with  sartain