INTRODUCTION. 17 



It not unfrequently 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 in alkali, to neutralize the effects of the acid. They 

 must afterwards be cleaned by repeated ablutions in warm 

 water. 



