Instruments of the Antienls. 349 



a glass globe of the size you want ; and, while it is red hot, 

 pour into it the melted mixture, along with a bit of colo- 

 phony, or black rosin. Turn it gently, in all directions, till 

 its whole interior surface be coated over. Take it imme- 

 diately off the tire, and pour off what is left, and keep it for 

 another occasion. Then with a diamond or an agate cut 

 the globe into as many mirrors as you think proper. The 

 same thing may be done with a mixture "of tin and anti- 

 mony. " 



8. I suppose my readers will agree with my author, that 

 the total silence of history respecting the time and place of 

 the introduction of glass mirrors, to which we may add the 

 inventor's name, is one of the strongest possible presump- 

 tions that they had their origin in very remote antiquity; 

 like the use of iron and the other common metals, alpha- 

 betical writing, the arithmetical digits, and other admirable 

 and highly useful invention's. Abat appears to me to prove 

 satisfactorily, that leaded glass was early used for mirrors ; 

 but he has not been able to discover any direct evidence that 

 silvered glass mirrors are equally antient. He only quotes 

 Isidore of Seville, Etymol. lib. xvi. cap. 18, where that 

 father says, " Sine hoc (argento vivo) neqtie urgent urn neque 

 <ses inaurari potest : — Seruatur autem melius in vasis vitreis ; 

 7?a?n cent eras mater ins perforat. Without mercury neither 

 silver nor copper can be overlaid with gold. — But it is kept 

 best in glass vessels, for it perforates other materials." 

 Abat observes, that such an opinion would induce people to 

 keep their mercury in glass vessels ; that when mercury 

 contains lead or tin it adheres, though not very strongly, 

 to glass, and thus presents to the eye the exact appearance 

 of a silvered glass mirror ; that Pliny's word excogitaverat 

 implies, that the Sidonians had bestowed thought and pains 

 on their glass mirrors ; and that so simple a process a$ sil- 

 vering them, could not long escape such ingenious artists. 

 For, when they had once observed that mercury, mixed 

 with tin or lead, adheres to glass, it would not be difficult 

 for them to conceive, that foils of these metals, well imbued 

 with mercury, would have the same property. In short, 

 says Abat, an ingenious man, after some attempts, would 

 easily succeed in doing the rest; or, in other words, would 

 discover the process of silvering glass mirrors, which we 

 now practise. 



[To be continued.] 



animals growing afterwards uncommonly fat and sleek, the monks tried 

 its operation upon themselves, and suffered severely by the experiment. 

 Hence, says my forgotten author, the name Antimony, which signifies 

 An enemy to monks.— Translator. 



LVII. On 



