VOL. XXIX.] PHILOSOPHICAL TRANSACTIONS. ]7l 



dent that the salt in the lakes will be continually augmented, and the water 

 grow Salter and Salter. But in lakes that have an exit, as the lake of Genesaret, 

 otherwise called that of Tiberias, and the upper lake of Mexico, and indeed 

 in most others, the water being continually running ofF, is supplied by new 

 fresh river water, in which the saline particles are so few as by no means to be 

 perceived. 



Now if this be the true reason of the saltness of these lakes, it is not im- 

 probable but that the Ocean itself is become salt from the same cause, and we 

 are thereby furnished with an argument for estimating the duration of all things, 

 from an observation of the increment of saltness in their waters. For if it be 

 observed what quantity of salt is at present contained in a certain weight of the 

 water, of the Caspian Sea, for example, taken at a certain place, in the driest 

 weather ; and after some centuries of years the same weight of water, taken in 

 the same place, and under the same circumstances, be found to contain a sen- 

 sibly greater quantity of salt than at the time of the first experiment, we may 

 by the rule of proportion, make an estimate of the whole time wherein the 

 water would acquire its present degree of saltness. 



And this argument would be the more conclusive, if by a like experiment a 

 similar increase in the saltness of the Ocean should be observed: for that, 

 after the same manner as aforesaid, receives innumerable rivers, all which de- 

 posite their saline particles therein; and are again supplied, as I have elsewhere 

 showed, by the vapours of the Ocean, which rise from it in atoms of pure 

 water, without the least admixture of salt. But the rivers in their long passage 

 over the earth imbibe some of its saline particles, though in so small a quantity 

 as not to be perceived, unless in these their depositories after a long tract of 

 time. And if, on repeating the experiment, after another equal number of 

 ages, it shall be found that the saltness is further increased with the same in- 

 crement as before, than what is now proposed as hypothetical, would appear 

 little less than demonstrative. *But since this argument can be of no use to 

 ourselves, it requiring very great intervals of time to come to our conclusion, 

 it were to be wished that the ancient Greek and Latin authors had delivered 

 down to us the degree of the saltness of the sea, as it was about 2000 years 

 ago: for then it cannot be doubted but that the difference between what is now 

 found and what then was, would become very sensible. I recommend it there- 

 fore to the society, as opportunity shall offer, to procure the experiments to be 

 made of the present degree of saltness of the Ocean, and of as many 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 



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