398 The Commercial Products of the Sea. 



they were not suited for the purpose intended, and there- 

 fore unappreciated here. 



A similar mode of ornamentation, but less artistic, and 

 of a much coarser character, is familiar in the carved 

 "pilgrim shells," which are brought from Bethlehem and 

 other parts of the Holy Land, having religious legends and 

 figures engraved on them. 



One process of working pearl shell is similar to that of 

 engraving metals in relief by the aid of corrosive acids 

 and the etching-point. The shell is first divided as may 

 be necessary, and the designs or patterns drawn upon it 

 with an opaque varnish ; strong nitric acid is then brushed 

 over the shell repeatedly, until the parts untouched or 

 undefended by the varnish are sufficiently corroded or 

 eaten away by the acid. The varnish being now washed 

 off, the device, which the acid has not touched, is found to 

 be nicely executed. If the design is to be after the manner 

 of common etching on copper, the process upon the shell 

 is precisely the same as the process upon the metal. 



Several other shells, having sufficiently brilliant tints in 

 their nacreous or iridescent hues, are used for some of the 

 industrial and ornamental purposes- to which mother-of- 

 pearl is applied, and it will be necessary to give a brief 

 notice of these. The ear-shells (Haliotis family) are much 

 used for inlaying work by the Birmingham manufacturers, 

 to give the varied shades to papier-mS,che ornaments and 

 fancy articles. They are sometimes called in trade "aurora 

 shells." There are about seventy species of these splendid 

 shells, of which we have one common British species of 

 small size {H. tuberculatd), with a silvery hue. In Jersey, 

 where it abounds, it is called the " ormer." These shells 

 have a row of holes following the course of the spine, and 

 have been named ear-shells from their resemblance in form 



