When we compare metals in regard to their fitness for mirrors, we shall soon perceive that the hardest of a white colour possess in the highest degree the necessary lustre. For this reason platina is preferable to all others, as is proved from the experiments made by the Count von Sickengen. Steel approaches nearest to this new metal, and silver follows steel; but gold, copper, tin and lead, are much less endowed with the requisite property. I have however observed among the ancients no traces of steel mirrors; and it is probable they did not make any of that metal, as it is so liable to become tarnished, or to contract rust. An ancient steel-mirror is indeed said to have been once found, but as some marks of silvering were perceived on it, a question arises whether the silvered side was not properly the face of the mirror[147]. Besides, every person knows that a steel mirror would not retain its lustre many centuries amidst ruins and rubbish. The greater part of the ancient mirrors were made of silver, not on account of costliness and magnificence, as many think, but because silver, as has been said, was the fittest and the most durable of all the then known unmixed metals for that use. In the Roman code of laws, when silver plate is mentioned, under the heads of heirship and succession by propinquity, silver mirrors are rarely omitted; and Pliny[148], Seneca[149], and other writers, who inveigh against luxury, tell us, ridiculing the extravagance of the age, that every young woman in their time must have a silver mirror. These polished silver plates may however have been very slight, for all the ancient mirrors, preserved in collections, which I have ever seen, are only covered with a thin coat of that expensive metal; and in the like manner our artists have at length learned a method of making the cases of gold and silver watches so thin and light, that every footman and soldier can wear one. At first the finest silver only was employed for these mirrors, because it was imagined that they could not be made of that which was standard; but afterwards metal was used of an inferior quality. Pliny tells us so expressly, and I form the same conclusion from a passage of Plautus[150]. Philematium having taken up a mirror, the prudent Scapha gives her a towel, and desires her to wipe her fingers, lest her lover should suspect by the smell that she had been receiving money. Fine silver however communicates as little smell to the fingers as gold; but it is to be remembered that the ancients understood much better than the moderns how to discover the fineness of the noble metals by the smell, as many modes of proof which we use to find out the alloy, were to them unknown. Money-changers therefore employed their smell when they were desirous of trying the purity of coin[151]. The witty thought of Vespasian, who, when reproached on account of his tax upon urine, desired those who did so to smell the