rationability

— And, if on twenty pounds of fluid, one of humours is to be defalcated: ſhould you evaporate the whole together to one ſcruple, would you not always find in that ſcruple ſtill one grain of humours?—I will ſay no more, nor lay greater ſtreſs on that ſubjeft, but leave every one to judge for himſelf, according to his own private ſenſe, of the rationabllity of ſuch proceedings.