230 Voyafie to the Western Coast of Africa. 



clouds into the sea, and the squall was beginning to dissipate, 

 we distinctly perceived the electric matter to be rising upwards 

 from the water. During the continuance of these tornadoes we 

 never used our conductors ; and it is worthy of consideration 

 whether it would not be more safe for ships iTever to have re- 

 course to them. When the conductor is fixed to the mast-head, 

 a chain is attached to it, and brought down one of the back stays 

 into the water ; but if any accident were to break off the com- 

 munication with the water, the conductor, so far from proving 

 a protector, would only become a source of danger, by pow- 

 erfully attracting the electric fluid, without affording any 

 means for its escape. When, therefore, I discovered, that there 

 existed some quality in the ship itself, perhaps the masts and 

 yards, which caused the thunder and lightning to cease when it 

 approached the ship, I considered it most expedient not to try 

 what the effects of the conductor might be, and during all the 

 period that we were exposed to these tornadoes, no accident 

 ever occurred to us. 



On making Artificial Pearls. 



M. HESE are small globules, or pear-shaped bulbs, blown in thin 

 glass, and each pierced with two opposite holes, by Avhich it may 

 be strung. These are afterwards prepared in such a manner as 

 to greatly imitate the rounded and brilhant concretions, reflect- 

 ing the iridescent colours, which are found in certain bivalve 

 shells, such as the pearl-mussel, &c., and which bear the name 

 of oriental pearls. 



We can perfectly imitate the brilhancy and reflection of these 

 natural pearls, by means of a liquid, termed Essence of Pearl, 

 and which is prepared by throwing into liquid ammonia the bril- 

 liant particles which are separated by friction and washing from 

 the scales of a small river fish named the Bleak (Cyprinus al- 

 burnus). These pearly particles, thus suspended in the ammo- 

 nia, can be applied to the whole interior of these glass bulbs, by 

 blowing it into them ; after which, the ammonia is volatilized by 

 gently heating them. 



It is said that some manufacturers do not apply the ammonia ; 



