But among the substances which are furnished in common by the various animals, it is the gall, we may say, that is the most efficacious of all. The properties of this substance are of a calorific, pungent, resolvent, extractive, and dispersive nature. The gall of the smaller animals is looked upon as the most penetrating; for which reason it is that it is generally considered the most efficacious for the composition of eye-salves. Bull's gall is possessed of a remarkable degree of potency, having the effect of imparting a golden tint to the surface of copper even and to vessels made of other metals. Gall in every case is prepared in the following manner: it is taken fresh, and the orifice of the vesicle in which it is contained being tied fast with a strong linen thread, it is left to steep for half an hour in boiling water; after which it is dried in the shade, and then put away for keeping, in honey.

That of the horse is condemned, being reckoned among the poisons only. Hence it is that the Flamen[1] of the Sacrifices is not allowed to touch a horse, notwithstanding that it is the custom to immolate one[2] of these animals at the public sacrifices at Rome.