ORDER II. SEA WATER. 
279. SEA WATER is a very heterogeneous compound, not 
only containing a considerable portion of saline substances, but 
holding also suspended in it an infinite number of minute animal 
and vegetable particles, to the gradual putrefaction of which its 
peculiarly nauseous and bitter taste, at the surface, is in some 
measure to be attributed. 
The average quantity of salt in sea water is estimated to 
amount to about one-thirtieth part of its weight. It likewise 
contains a certain portion of muriat of magnesia, sulphat of 
magnesia or Epsom salts (199), and a small quantity of sulphat 
of lime (192). Sea water, taken from a great depth, has not the 
bitterness which the water of the surface has : it is only saline. 
No natural waters, if we except certain brine springs 
and salt lakes, are so saline as those cf the ocean; and 
the latter differ, in this respect, in different parts of the 
world. At the tropic, the sea is in general more salt than 
it is at the poles, a wise ordination to preserve it, in those 
climates, from the great tendency to putrefaction : and, 
at a considerable depth, it is always found more salt 
than at the surface. The water of the Baltic is much 
less salt than that of the Atlantic ; and it is a remarkable 
circumstance, that its saline contents are increased by 
a west wind, but still more so by a gale from the north 
west. 
Some philosophers have endeavoured, but to little 
purpose, to account, from second causes, for the salt- 
ness of the ocean. Dr. Halley persuaded himself that 
it might have been gradually acquired, in very minute 
portions, by a deposit of salt washed down from the 
land by rivers, and that, as it could not be carried off 
by evaporation, instead of being diminished, it must be 
constantly increasing. But this idea of salting the sea 
