316 . THE OCEAN. 



of these lakes as can be come at, that they may stand upon record 

 for the benefit of future ages. 



" If it be objected that the water of the ocean, and perhaps of some 

 of these lakes, might at the first beginning of things, in some mea- 

 sure contain salt, so as to disturb the proportionality of the increase 

 of saltness in them, I will not dispute it : but shall observe that such 

 a supposition would by so much contract the age of the world, 

 within the date to be derived from the foregoing argument, which' 

 is chiefly intended to refute the ancient notion, some have of late 

 entertained, of the eternity of all things ; though perhaps by it the 

 world may be found much older than many have hitherto ima- 

 gined." 



It must be admitted, observes Dr. Thomson upon the above hy- 

 pothesis, that this, is an ingenious and plausible speculation ; but it 

 will not bear a rigid examination. We have no evidence whatever, 

 that the sea was not salt at its original formation. Indeed there is 

 presumption in favour of that opinion 5 because many of tiie ani. 

 mals which it contains cannot live in fresh water. Hence we must 

 either admit that the sea remained for many ages uninhabited, or 

 that it was salt at its first formation. But, granting that the sea 

 was originally fresh, it would not follow that it became salt by eva- 

 poration, unless \ve were certain that the vapour which rises from 

 the sea is absolutely destitute of salt. But we have evidence that 

 this is not the case. Margraaff found salt in rain water, which must 

 have been originally raised by evaporation, either from the sea or 

 the land ; and, if we suppose the latter, the supposition makes more 

 strongly for the reality of the vapour from sea-water containing 

 Some salt. But even if this point were given up, still there is an- 

 other consideration which would make it difficult or impossible to 

 deduce any conclusions from the rate at which the saltrcess of the 

 sea increases. It is true that salt is mixed, to a certain amount, 

 with almost every mineral in nature, as follows from the galvanic 

 experiments of Mr. Davy. But the proportion of it is very various 

 in different places. Sometimes, as in Cheshire and in Poland, we 

 find it deposited in prodigious quantities, so as to form beds of 

 enormous thickness. In other cases it is loosely scattered, but in 

 very inconsiderable quantities, in rocks and the soil. While in other 

 cases it is so intimately mixed, that it cannot be separated by auy 



