THE SALTS OF THE SEA. 201 



kinds from the rocks and soil, and empty them into tlie sea, there 

 is no doubt. These salts can not be evaporated, v/e know ; and 

 we also know that many of the lakes, as the Dead Sea, which re- 

 ceive rivers and have no outlet, are salt. Hence the inference by 

 some philosophers (§ 502) that these inland water-basins received 

 their salts from the washings of the soil ; and consequently the 

 conjecture arose that the great sea derived its salts from the same 

 source and by the same process. But, and per contra, though 

 these solid ingredients can not be taken out of the sea by evapo- 

 ration, they can be extracted by other processes. We know that 

 the insects of the sea do take out a portion of them, and that the 

 salt ponds and arms which, from time to time in the geological 

 calendar, have been separated from the sea, afford an escape by 

 which the quantity of chloride of sodium in its waters — ^tlie most 

 abundant of its solid ingredients — is regulated. The insects of 

 the sea can not build their structures of this salt, for it would dis^ 

 solve again, and as fast as they could separate it. But here the 

 ever-ready atmosphere comes into play, and assists the insects in 

 regulating the salts. It can not take them up from the sea, it is 

 true, but it can take the sea away from them ; for it pumps up the 

 water from these pools that have been barred off, transfers it to 

 the clouds, and they deliver it back to the sea as fresh water, leav- 

 ing the salts it contained in a solid state behind. 



566. These are operations that have been going on for ages ; 

 proof that they are still going on is continually before our eyes ; 

 for the "hard water" of our fountains, the marl-banks of the val- 

 leys, the salt-beds of the plains, Albion's chalky cliffs, and the 

 coral islands of the sea, are monuments in attestation. 



567. There is no proof, nor is there any reason for the belief, 

 that the sea is growing Salter or fresher. Hence we infer that the 

 operations of addition and extraction are reciprocal and equal; 

 that the effect of rains and rivers in washing down is compensated 

 by the processes of evaporation and secretion in taking out. 



568. If the sea derived its salts originally from the rivers, the 

 geological records of the past would show that river beds were 

 scored out in the crust of our planet before the sea had deposited 

 any of its fossil shells and infusorial remains upon it. If, there- 



