1828 A. Sherburne (1831) i. 24 My share was..from thirty to forty gallons of fourth proof Jamaica rum.
1835 J. F. Cooper (1860) vi. 92 Those parts..being indicated by touches of red, nearly as bright as Fourth-proof brandy.
a1861 T. Winthrop (1862) ix. 91 I'd seen 'em gettin' up the sham kind [of miracle],..and I knowed the fourth-proof article.