TINNING, PLATING, &C. 



distinct by means of gold, might have been made with more ju 

 than is neiuTdlly supposed; for Burton is of opinion, that a look. 

 1114. glass made with a covering of gold and quicksilver, would re. 

 ile;t more light than one made in the ordinary way with tin and 

 quicksilver*; and hence Pliny's expression, certiorcm imaginetn 

 reddi auto apposito aversis, will be accurately true. 



Alexander Aphrodiseus flourished towards the end of the second 

 century; he wrote several works in Greek, and among the rest 

 two books of Problems ; one of his problems is this + : 



A*a TI roc, 



Why are glass specula so very resplendent? 



The only part of the answer which we are concerned with, is, 



Because they besmear the inside of them with tin. 





The Greek word which I have here rendered besmear, does not 

 clearly point out the manner in which the operation of fixing the 

 tin upon the glass was performed. Pliny uses a Latin word 

 (illitum) of exactly the same import as this Greek one, when he 

 speaks of copper vessels being tinned ; and as in that operation, 

 tin is melted and spread over the surface of the copper, I see no 

 difficulty in supposing, that the tin may have been, in the time of 

 Alexander Aphrodiseus, melted and spread over the surface of the 

 glass, wh< n previously heated. 



Having carried up the invention of covering glass specula with a 

 metallic coating to the second century, we may be the more ready 

 to adnr.it that the Sydonians possessed this art, before Pliny wrote 

 Ms Natural History : for in that work he not only praises them for 

 their former iii< -n'lity in various glass manufactures, but he adds 

 and they had iim-ntid specula alsoj. Now there is some reason 



* Oo p r.irroit trouver le moyen de fairr tin inoillcur etamage, et je rrois 

 qu'on parvlcndroit en employant de 1'or et du vifargent. Hist. Nat. Bnffon. 

 Sup. torn. i. p. 451. 



T AAE3ANAPOT AtPOAlZEftS isrpixa awopn/uar* xai <ftij-ia wpeCxnjua-r*. 

 Parisiis, 15H- If c;iere be any doubr concerning th authenticity of these pro- 

 blrms I leave it to be discussed by the critics 



J Aliud (vitnim) flalu figuratus, aliud torno teritur, aliud ar^enti modo 

 crrlatur, Sydon- quondam iis officinis nobili, siquidem etiatn specula cxcojita- 

 rrut. Iliit. Nat. 1. xxivi. 



