Mother -of -Pear I and its Uses. 371 



The nacreous shells are formed by alternate layers of 

 very thin membrane and carbonate of lime ; but this alone 

 does not give the pearly lustre, which appears to depend 

 on minute undulations in the layers. The fibrous shells 

 consist of successive layers of prismatic cells containing 

 translucent carbonate of lime. The exquisitely fine series 

 of furrows upon the surface sheds a brilliant reflection of 

 colours according to the angle at which the light falls upon 

 them. 



The concrete composition of mother-of-pearl, being 

 deposited in annual layers, is excessively hard, and requires 

 good tools to work it ; sulphuric and other powerful acids 

 are brought to the aid of the circular saw, the drill, and 

 the file, and calcined sulphate of iron is used to give a 

 polish to the objects. The Japanese and Chinese have 

 evidently means and processes for working this material 

 which are unknown to us, for they give a finish and a 

 polish to their pearlwork carvings and inlayings, which the 

 skilful artists of the western world admire and envy. 



Besides its use for buttons, studs, the handles of knives, 

 fans, book-covers, card-cases, and other fancy articles, 

 mother-of-pearl is also employed by cabinet-makers, piano- 

 forte manufacturers, papier-mache workers, and others, for 

 inlaying. The range of articles made of this substance is 

 very extensive ; pen-holders, carved brooches, earrings, 

 buckles, sleeve-links, little boxes, and hundreds of others, 

 might be enumerated. 



The greatly increased use of this material in various 

 branches of manufacture, particularly those of an orna- 

 mental character, has more than doubled the price of the 

 shells. From 4000 to 5000 persons used to be engaged in 

 the manufacture at Birmingham, but the number has been 

 greatly reduced in consequence of other countries com- 



