LECTURE XI. 



ducing this substance into the inside of finely- 

 blown glass beads, slightly tinged with opaline 

 hues, a perfect imitation of real pearls might be 

 made: (for an attempt of a similar nature had 

 some years before been made in Italy, by filling 

 glass bubbles with quicksilver; but which was" im- 

 mediately discouraged; first, on account of the 

 pearls so prepared wanting the true colour, and 

 because they were judged to be dangerous by the 

 physicians. ) Jacquin was at first put to great dif- 

 ficulty in preserving the silver-coloured powder, 

 which, if not used quickly, becomes putrid, and dif- 

 fuses an intolerable smell. Attempts were made 

 to preserve it in spirits, but by this method the 

 lustre was entirely destroyed. It was at length 

 found, that volatile alkali possessed the power of 

 preserving the substance without injury to its co- 

 lour. Many years elapsed before the false pearls 

 became very common; and even so late as the 

 reign of Louis the Fourteenth it is said that a 

 French Marquis who possessed very little property, 

 but who was violently in love with a particular 

 lady, gained her affections by presenting her with a 

 rich string of these pearls, which cost him but three 

 .Louis's, but which the Lady, supposing them to 



LECT. II, N 



