By some persons the opinion is entertained that the sea has been gradually getting salter ever since the creation of the world. This, they say, arises from the evaporation of water free from salt, and the returns of the water to the sea, taking with it salt from the land.
765. What is the estimated amount of salt in the sea?
The amount of common salt in the various oceans is estimated at 3,051,342 cubic geographical miles, or about five times more than the mass of the mountains of the Alps.
766. What is the depth of the sea?
The extreme depth has not, probably, been ascertained. But Sir James Ross took soundings about 900 miles west of St. Helena, whence he found the sea to be nearly six miles in depth. Now, if we take the height of the highest mountain to be five miles, the distance from that extreme rise of the earth, to the known depth of the sea, will be no less than eleven miles.
767. Why are the waters of some springs impregnated with mineral matters?
Because the water passes through beds of soda, lime, magnesia, carbonic acid, oxides of iron, sulphate of iron, &c., &c., and takes up in some slight degree the particles of those minerals, according to the proportions in which they abound.
"Who hath measured the waters in the hollow of his hand, and meted out heaven with the span, and comprehended the dust of the earth in a measure and weighed the mountains in scales, and the hills in a balance?"—Isaiah xl.