ATTEMPTED EXPLANATION. 417 



of the rest in a group, the parts of which are 

 in chemical harmony with each other; but a 

 fluid holding compatible substances in solution 

 might have a very different constitution to that 

 of the sea. This is true. Let us, however, 

 recall what was remarked on a previous page, 

 upon the gross composition of the earth, from 

 which the ocean has derived its saline contents. 

 It was there stated that the earth en masse is 

 chiefly composed of seven elements silicium, 

 calcium, aluminum, magnesium, potassium, and 

 sodium, in union with oxygen. Hence it is 

 evident that the waters which wash the shores, 

 and receive the drainage of a world thus 

 framed, are not exposed, on the large scale, to 

 that mixture of heterogeneous ingredients, 

 which, upon a circumscribed view of the sub- 

 ject, we might be led to anticipate. With the 

 earth's gross composition in view, the number 

 and nature of the elements present in the water- 

 world might almost have been anticipated. Of 

 the seven elements, or the six oxides, silica, as 

 we are informed by chemistry, is not sensibly 

 soluble, and alumina, occurring in nature chiefly 

 in the form of clay, or locked up in the massive 

 granite as a silicate of alumina, presents little 

 probability of affording a solution. This re- 

 duces the list to the four elements which, in 

 combination with chlorine, iodine, bromine, sul- 



2 E 



