RUPERT'S Drops, a sort of glass-drops with long and slender tails, which burst to pieces on the breaking off those tails in any part; said to have been invented by prince Rupert, and therefore called by his name. Concerning the cause of this surprising phenomenon scarce any thing that bears the least appearance of probability has been offered. Their explosion is attended in the dark with a flash of light; and by being boiled in oil, the drops are deprived of their explosive quality.