According to Juba minium is also a production of Carmania,[1] and Timagenes says that it is found in Æthiopia. But from neither of those regions is it imported to Rome, nor, indeed, from hardly any other quarter but Spain ; that of most note coming from Sisapo,[2] a territory of Bætica, the mine of minium there forming a part of the revennes of the Roman people. Indeed there is nothing guarded with a more constant circumspection; for it is not allowable to reduce and refine the ore upon the spot, it being brought to Rome in a crude state and under seal, to the amount of about two thousand pounds per annum. At Rome, the process of washing is performed, and, in the sale of it, the price is regulated by statute; it not being allowed to exceed[3] seventy sesterces per pound. There are numerous ways, however, of adulterating it, a source of considerable plunder to the company.[4]

For there is, in fact, another kind[5] of minium, found in most silver-mines as well as lead-mines, and prepared by the calcination of certain stones that are found mixed with the metallic vein—not the minerals, however, to the fluid humours of which we have given[6] the name of quicksilver; for if those are subjected to the action of fire they will yield silver—but another kind of stone[7] that is found with them. These barren[8] stones, too, may be recognized by their uniform leaden colour, and it is only when in the furnace that they turn red. After being duly calcined they are pulverized, and thus form a minium of second-rate quality, known to but very few, and far inferior to the produce of the native sand that we have mentioned.[9] It is with this substance, then, as also with syricum, that the genuine minium is adulterated in the manufactories of the company. How syricum is prepared we shall describe in the appropriate place.[10] One motive, however, for giving an under-coat of syricum to minium, is the evident saving of expense that results therefrom. Minium, too, in another way affords a very convenient opportunity to painters for pilfering, by wash- ing their brushes,[11] filled with the colouring matter, every now and then. The minium of course falls to the bottom, and is thus so much gained by the thief.

Genuine minium ought to have the brilliant colour of the kermes berry;[12] but when that of inferior quality is used for walls, the brightness of it is sure to be tarnished by the moisture, and this too, although the substance itself is a sort of metallic mildew. In the mines of Sisapo, the veins are composed exclusively of the sandy particles of minium, without the intermixture of any silver whatever; the practice being to melt it like gold. Minium is assayed by the agency of gold in a state of incandescence: if it has been adulterated, it will turn black, but if genuine, it retains its colour. I find it stated also that minium is adulterated with line; the proper mode of detecting which, is similarly to employ a sheet of red hot iron, if there should happen to be no gold at hand.

To objects painted with minium the action of the sun and moon is highly injurious. The proper method of avoiding this inconvenience, is to dry the wall, and then to apply, with a hair brush, hot Punic wax, melted with oil; after which, the varnish must be heated, with an application of gall-nuts, burnt to a red heat, till it quite perspires. This done, it must be smoothed down with rollers[13] made of wax, and then polished with clean linen cloths, like marble, when made to shine. Persons employed in the manufactories in preparing minium protect the face with masks of loose bladder-skin, in order to avoid inhaling the dust, which is highly pernicious; the covering being at the same time sufficiently transparent to admit of being seen through.

Minium is employed also for writing[14] in books; and the letters made with it being more distinct, even on gold or marble, it is used for the inscriptions upon tombs.