260 THE PHYSICAL GEOGKAPHY OF THE SEA. 



ing to show that the sea was ever fresh ; on the contrary, they 

 both afford circumstantial evidence sufficient for the belief that 

 the sea was salt as far back as the morning of creation, or at least 

 as the evening and the morning of the day when the dry land ap- 

 peared. That the rains and the rivers do dissolve salts of various 

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

 is no doubt. These salts can not be evaporated, we 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 that these inland water-basins received their 

 salts wholly 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 — the 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, 

 leaving the salts it contained in a solid state behind. 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 wa- 

 ter" of our fountains, the marl-banks of the valleys, the salt-beds 

 of the plains, Albion's chalky cliffs, and the coral islands of the * 

 sea, are monuments in attestation. These masses of solid matter 

 have been secreted from the sea waters ; they express the ability 

 of these creatures to prevent the accumulation of salts in the sea. 

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

 Their antiquity, that the sca Is growiug Salter or fresher. Hence 

 we infer that the operations of addition and extraction are recip- 

 rocal and equal; that the effect of rains and rivers in washing 



