TINNING, PLATING, &C. 



upon tho (in leaf, in such a manner as (o sweep off the redundant 

 quicksilver, which is not incorporated with tin- tin ; leaden weight-) 

 are then placed on the lass ; and in a little time the quicksilvered 

 tin-foil adheres so firmly to the glass, that the weights may be re 

 moved without any danger of its falling off. The glass thus sil- 

 vered is a common looking.glass. About two ounces of quicksilver 

 are sufficient for covering three square feet of glass. 



It is generally believed, that the art of making looking-glasses, 

 by applying to their back surface a metallic covering, is a very 

 modern invention. Muratori expressly says, that glass specula, 

 such he means as are now in use, are not of. any great antiquity. 

 Serx autem antiquitati novimus fuisse specula^ quorum usus nun. 

 quam desiit ; sed eorum fabricam apud I talus unice forsan Veneti 

 per tempora multa servarunt et adhuc servant : qua: tamen alio 

 translata nunc in aliis quoque regnis floret*. The authors of the 

 French Encyclopedic + have adopted the same opinion, ami quoted 

 a Memoir, printed in the twenty-third volume of the Academy of 

 Inscriptions, &c. II est d'autant plus etonnant que les anciens 

 n'aient pas connu I'art de rendre le verre propre a conserver la re- 

 presentation des objets, en appliquant I'etain derriere les glaces, 

 que les progres de la decouverte du verre furent, chez eux, pousses 

 fort loin. Mr. Nixon, in speaking of the glass specula of the 

 ancients, says, " before the application of quicksilver, in the con. 

 struction of these glasses, (which I presume is of no great anti- 

 qaity), the reflection of images by such specula must have been 

 effected by their being besmeared behind, or tinged through with 

 some dark colour, especially black J." I have bestowed more time 

 in searching out the age in which the applying a metallic covering 

 to one side of a looking.glass was introduced, than the subject, in 

 the estimation of many, will seem to deserve; and, indeed, more 

 than it deserved in my own estimation : but the difficile* nugce, 

 the stultus labor ineptiarum, when once the mind gets entangled 

 with them, cannot be easily abandoned : one feels, moreover, a 

 singular reluctance in giving up an unsuccessful pursuit. The 

 reader would pardon the introduction of this reflection, if he knew 

 how many musty volumes 1 turned over, before I could meet with 

 any information which could satisfy me, in any degree, on this sub- 



Mumtori Anliq. vol. ii. p. 39'. f Art. Miroir. 



t Phil. Trans. 1758. p. 60s?. 



