H. J. Clayton, Clayton's Quaker Cook-Book
“ The most scrupulous attention being paid to the keeping of all the utensils used scrupulously clean, and so thoroughly work the mass, that every particle of milk is expelled. The greatest evil to be guarded against, is the too free use of salt, which for this purpose should be of the utmost purity and refined quality. I am satisfied, from personal observation, that the butter made at the Jersey Farm, at San Bruno, in the vicinity of San Francisco, in every respect equals in quality the celebrated Darlington, Philadelphia. ”
