with wine, it has the effect of an emmenagogue. Another use that is made of it, is for coating the inside of copper vessels, it rendering them proof against the action of fire. It has been already[2260] stated that bitumen was formerly employed for staining copper and coating statues. It has been used, too, as a substitute for lime; the walls of Babylon, for instance, which are cemented with it. In the smithies they are in the habit of varnishing iron and heads of nails with it, and of using it for many other purposes as well. CHAP. 52.—ALUMEN, AND THE SEVERAL VARIETIES OF IT; THIRTY-EIGHT REMEDIES. Not less important, or indeed very dissimilar, are the uses that are made of alumen;[2261] by which name is understood a sort of brine[2262] which exudes from the earth. Of this, too, there are several kinds. In Cyprus there is a white alumen, and another kind of a darker colour. The difference, however, in their colour is but trifling in reality, though the uses made of them are very dissimilar; the white liquid alumen being employed for dyeing[2263] wool of bright colours, and the black, on the other hand, for giving wool a tawny or a sombre tint. Gold, too, is purified[2264] by the agency of black alumen. Every kind of alumen is a compound of slime and water, or in other words, is a liquid product exuding from the earth; the concretion of it commencing in winter, and being completed by the action of the summer sun. That portion of it which is the first matured, is the whitest in appearance. The countries which produce this substance, are Spain, Ægypt, Armenia, Macedonia, Pontus, Africa,[2265] and the islands of Sardinia, Melos, Lipara, and Strongyle:[2266] the most esteemed, however, is that of Egypt,[2267] the next best being the produce of Melos. Of this last kind there are also two varieties, the liquid alumen, and the solid. Liquid alumen, to be good, should be of a limpid, milky, appearance: when rubbed between the fingers it should be free from grit, and productive of a slight sensation of heat. The name given to it is “phorimon.”[2268] The mode of detecting whether or not it has been adulterated, is by the application of pomegranate-juice; for if genuine, it will turn black on combining with the juice. The other, or solid alumen, is pale and rough in appearance, and turns black on the application of nut-galls; for which reason it is known by the name of “paraphoron.”[2269]