THE PEARL OYSTER. 913 



our debt to the oyster. Having regarded that placid 

 creditor as an article of food, I now propose to treat him 

 as an assistant to the toilet. And, looking at him in that 

 point of view, here is not a bad instalment of the aforesaid 



debt, contributed by Barry Cornwall :- 



" Within the midnight of her hair, 

 Half hidden in its deepest deeps, 

 A single peerless, priceless pearl, 

 (All filmy-eyed) for ever sleeps. 

 Without the diamond's sparkling eyes, 

 The ruby's blushes there it lies, 

 Modest as the tender dawn, 

 When her purple veil's withdrawn 

 The flower of gems, a lily cold and pale. 

 Yet, what doth all avail ? 

 All its beauty, all its grace ? 

 All the honours of its place ? 

 He who plucked it from its bed, 

 In the far blue Indian Ocean, 

 Lieth, without life or motion, 

 In his earthy dwelling dead ! 

 All his children, one by one, 

 When they look up to the sun, 

 Curse the toil by which he drew 

 The treasure from its bed of blue." 



Costly as pearls are, they are merely the calcareous 

 production of molluscs. Diamonds have elsewhere been 

 shown to be merely charcoal ; the pearl is little else but 

 concentric layers of membrane and carbonate of lime. (<:) 



(c) The chemical composition of the Pearl is carbonate of lime, 

 associated with a small proportion of organic matter : it is easily 

 affected by acids and foetid gases, and may be calcined on exposure to 

 heat. It possesses a lustre peculiar to itself, which is known as the 

 " orient." Its specific gravity is 2-5 to 2-7, those found on the coast of 

 South America, termed Panama Pearls, being somewhat denser than 

 the Oriental Pearls. 



