370 The Commercial Products of the Sea. 



CHAPTER II. 



MOTHER-OF-PEARL AND ITS USES. 



Composition of nacreous shells Their extensive employment in art and 

 manufacture Explanation of prismatic colours Varieties of mother-of- 

 pearl shells entering into commerce Purposes to which they are applied 

 Statistics of imports Diving for the shells in the Pacific Pearl fishery 

 of Western Australia Papier-mache work Other nacreous and iridescent 

 shells used The ear-shells or Haliotids. 



AMONG the products obtained from the sea which are' used 

 by the artist and art-manufacturer, mother-of-pearl and 

 other nacreous and iridescent shells form important articles 

 of commerce, to which we will now direct attention. 



The mother-of-pearl shells which our manufacturers 

 transform into so many articles of ornament and utility, 

 are those of the large oysters, obtained in many different 

 parts of the world, chiefly the shells of Meleagrina margari- 

 tifera. 



Shells are composed of carbonate of lime, with a small 

 proportion of animal matter. The source of this lime is to 

 be looked for in their food. The texture of shells is various 

 and characteristic. Some when broken present a dull 

 lustre like marble or china, and are termed porcelaneous ; 

 others are pearly or nacreous; some have a fibrous structure; 

 some are horny, and others are glassy and transparent. 



