a : the first matter of the philosophers’ stone composed of salt, sulfur, and mercury
b : gripe’s egg
: a medicine made of saffron and the yolk of an egg and once considered a cure for plague and poison
Considered to be a form of the Philosopher’s Stone.
(The). A preservative against poison, and a cure for the plague; a panacea. The shell of a new egg being pricked, the white is blown out, and the place filed with saffron or a yolk of an egg mixed with saffron.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894