MOLLUSCA. 231 



porcellaneous shells. In general, however, it happens that, 

 when shells become dry, they lose much of their natural 

 lustre. This may be very easily restored, by washing them 

 with a little water, in which a small portion of gum arabic 

 has been dissolved, or with the white of an egg. This is 

 the simplest of those processes which are employed, and is 

 used not only by the mere collector, but by the scientific 

 conchologist. There are many shells of a very plain ap- 

 pearance on the outside, by reason of a dull epidermis or 

 skin with which they are covered. This is removed by soak- 

 ing the shell in warm water, and then rubbing it off with a 

 brush. When the epidermis is thick, it is necessary to mix 

 with the water a small portion of nitric acid, which, by dis- 

 solving a part of the shell, destroys the cohesion of the epi- 

 dermis. This last agent must be employed with great cau- 

 tion, as it removes the lustre from all the parts exposed to 

 its influence. The new surface must be polished with lea- 

 ther, assisted by tripoli. But, in many cases, even these 

 methods are ineffectual, and the file and the pumice-stone 

 must be resorted to, in order to rub off the coarse external 

 layers, that the concealed beauties may be disclosed. Much 

 address and experience are necessary in the successful em- 

 ployment of this last process. But it must be confessed that 

 the reward is often great. When thus prepared, even the 

 common mussel is most beautiful. 



The arrangement of shells in a cabinet must depend, in a 

 great degree, on the taste and fortune of the collector. If 

 ornament is the object in view, it will be indispensably ne- 

 cessary to have the shells placed in glass cases, where they 

 may be distinctly seen. But where a collection of shells is 

 formed for amusement, they may be kept in drawers, each 

 species placed in a paper case, or in a cup of wood, glass, or 



