INTRODUCTION. 9 



dermis will not separate from the shell, it is also necessary 

 to use muriatic acid, after they have undergone the above- 

 mentioned process. When they are perfectly dry, the 

 acid is applied with a fine brush, dipped in sand, to the 

 parts which require it. After the adhesions, &c. are re- 

 moved, the shell must be immersed in alkali, to neutralize 

 the effects of the acid, and then well washed in warm wa- 

 ter. As these shells are not susceptible of so fine a polish 

 as the smoother varieties, it is usual to give them an arti- 

 ficial gloss by brushing them over with a weak solution 

 of gum-arabic. 



Corals, which are so justly admired for their delicate 

 structure, elegant ramifications, and great beauty, may 

 be cleaned in a similar manner, by steeping them a few 

 days in the solution of potash and soft soap ; after which, 

 they should be carefully brushed in warm water. 



It not unfiequently happens that corals are discolored 

 by some extraneous substance; when this is the case, the 

 part discolored must be immersed in a weak solution of 

 muriatic acid until the outer surface is removed, and then 

 dipped ill alkali, to neutralize the eflfects of the acid. 

 They must afterwards be cleaned by repeated ablutions 

 in warm water. 



