74 THE CHEMISTRY OF CREATION. 



of one of the islands of the Pacific. These rocks 

 are composed of crystallized carbonate of lime, 

 perhaps originally coral, but by exposure to the 

 air, and by the percolation of water, the loose 

 particles of calcareous matter have been washed 

 away, and the whole mass presents in conse- 

 quence a very brilliant crystalline appearance. 



The island is represented in the cut. Other 

 instances* of the extensive influence of the dis- 



* The baths of San Philippe, in Tuscany, arc mentioned by 

 Sir Charles Lyell as yielding waters which contain so much 

 lime in solution as to yield a stratum a foot thick in four 



