Note 52 — PETER KALM’s TRAVELS. (continued 5)

December the 6th. On long voyages the sailors sometimes catch such fish as are known to none of the ship’s company; but as they are very greedy after fresh provisions, they seldom abstain from eating them, however it proves often venturing too much, experience having shown, that their want of caution has often cost them their lives, for sometimes poisonous fish are caught. But there is a method of finding them out, as I have heard from several captains of ships: it is usual when such unknown fish are boiled, to put a silver button, or any piece of silver into the kettle, which if the fish be poisonous, will turn quite black, but if it be not, it will not change: some of the seamen referred to their own repeated experience.52