Good Yeast

Boil a handful of hops in 3 pints of water; add 3 mashed boiled potatoes; strain, and mix with a cupful of flour; set aside to cool, and then add a tea-spoonful of sugar, and bottle up for use. A more permanent ferment is made by boiling a quantity of wheat-bran and hops in water; the decoction is not long in fermenting, and when this has taken place, throw in a sufficient portion of bran to form the whole into a thick paste, which work into balls, and afterward dry by a slow heat. When wanted for use, they are broken, and boiling water is poured upon them; having stood a proper time, the fluid is decanted, and in a fit state for leavening bread. 

[Maine Farmer's Almanac, 1852]