392 THE CHEMISTRY OF CREATION. 



and crevasses is highly remarkable.* The colour 

 also of the bed upon which the water lies 

 greatly influences the colour presented by the 

 latter. At Capri, in the Gulf of Naples, are 

 two grottos remarkable for the exquisite colour 

 of the water seen in them; The sea at the Blue 

 Grotto is most remarkably clear to a very 

 great depth, so that the smallest objects may be 

 distinctly seen on the light bottom at a depth 

 of several hundred feet. All the light that 

 enters the grotto, the entrance of which is only 

 a few feet above the level of the sea, in the 

 precipitous rock opening on the surface of the 

 water, must penetrate the whole depth of the 

 sea, probably several hundred feet, before it 

 can be reflected into the grotto from the clear 

 bottom. The light acquires by this means so 

 deep a blue colouration from the vast body of 

 water through which it has passed, that the 

 dark walls of the cavern are illuminated by a pure 

 blue radiance, and the most differently coloured 

 objects below the surface of the water are 

 made to appear tinged with blue. In the Green 

 Grotto the depth is less, and the yellow tint of 

 the subjacent rocks alters the colour of the 

 reflected light from blue to green. Some parts 

 of the Mediterranean Sea are found to present 



* Professor Bunsen notices the same appearances in the 

 glaciers of the Jokull in Iceland. 



