[151] Arrianus in Epictet. i. cap. 20, p. 79.
[152] Among the remaining passages of the ancients with which I am acquainted, in which mention is made of silver mirrors, the following deserves notice. Chrysostom, Serm. xvii. p. 224, who, in drawing a picture of the extravagance of the women, says, “The maid-servants must be continually importuning the silversmith to know whether their lady’s mirror be yet ready.” The best mirrors therefore were made by the silversmiths. It appears that the mirror-makers at Rome formed a particular company; at least Muratori, in Thesaur. Inscript. Clas. vii. p. 529, has made known an inscription in which collegium speculariorum is mentioned. They occur also in Codex Theodos. xiii. tit. 4, 2. p. 57, where Ritter has quoted more passages in which they may be found. But perhaps the same name was given to those who covered walls with polished stones, and in latter times to glaziers.
[153] Lib. xxxiii. c. 9. p. 627, and lib. xxxiv. c. 17, p. 669.
[154] Philosophical Transactions, vol. lxvii. p. 296.
[155] Quomodo Historia sit conscrib. cap. 51, Bipont edition, iv. p. 210, 535. Commentators have found no other way to explain κέντρον (a word which occurs in Lucian’s description of the mirror), than by the word centre, to which, according to their own account, there can be here no allusion. In my opinion κέντρον signifies those faulty places which are not capable of a complete polish, on account of the knots or cracks which are found in them. Lucian therefore speaks of a faultless mirror which represents the image perfect, as he afterwards informs us.
[156] As the account of these experiments is given only in an expensive work, which may not often fall into the hands of those who are best able to examine it, I insert it here. “The ancient mirror, which I examined, was a metallic mixture, very tender and brittle, and of a whitish colour inclining to grey. When put into the fire, it remained a long time in a state of ignition before it melted. It was neither inflammable nor emitted any smell like garlic, which would have been the case had it contained arsenic. It did not either produce those flowers which are generally produced by all mixtures in which there is zinc. Besides, the basis of this mixture being copper, it would have been of a yellow colour had that semi-metal formed a part of it. I took two drams of it and dissolved them in the nitrous acid. A solution was speedily formed, which assumed the same colour as solutions of copper. It precipitated a white powder, which I carefully edulcorated and dried. Having put it into a crucible with a reductive flux, I obtained lead very soft and malleable.
“Having filtered the solution, I took a part of it, upon which I poured an infusion of gall-nuts, but it produced no change. A solution of gold, which I poured upon another part, made it assume a beautiful green colour; but no precipitate was formed: which is sufficient to prove that there was neither iron nor tin in the mixture.
“On the remaining part of the solution I poured a sufficient quantity of the volatile alkali to dissolve all the copper that might be contained in it. The solution became of a beautiful sapphire blue colour, and a white precipitate was formed. Having decanted the liquor, and carefully edulcorated the precipitate, I endeavoured to reduce it; but whether it was owing to the quantity being too small, or to my not giving it sufficient heat, I could not succeed. I had recourse therefore to another method.
“I took the weight of two drams of the mixture, which I brought to a high state of ignition in a cuppel. When it was of a whitish-red colour, I threw upon it gradually four drams of sulphur, and when the flame ceased, I strengthened the fire in order to bring it to complete fusion. By these means I obtained a tender brittle regulus, whiter than the mixture, in which I observed a few small needles. Being apprehensive that some copper might still remain, I sulphurated it a second time, and then obtained a small regulus which was almost pure antimony.
“It results from these experiments, that the metal of which the ancients made their mirrors was a composition of copper, regulus of antimony, and lead. Copper was the predominant, and lead the smallest part of the mixture; but it is very difficult, as is well known, to determine with any certainty the exact proportion of the substances contained in such compositions.”