OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 
205 
nourished by sea-water, or from other animals that live upon sea-weeds, thus deriving 
their whole mineral substance either directly or indirectly from the sea. I have availed 
myself of the means which the organisms of the sea furnish, to determine a great 
number of elements that thus must exist in solution in sea-water. 
As to this great number of elements contained in the sea-water, we might ask one 
question, which is of great importance for the history of the earth, viz. how all these 
elements got into the sea, whether they were in the original sea, or subsequently got 
into the sea, where they are now slowly accumulating. When we consider that the sea 
constantly loses a great quantity of pure water by evaporation, and that a large part of 
this water falls on the land, dissolves a number of substances from it, and carries them 
at last into the sea, where they constantly would increase in quantity if it were not for 
its organisms which deprive it again of them, we may well suppose that these two 
effects, of which the one acts to increase, and the other to diminish the quantity of 
mineral substances in sea-water, are pretty equal, and leave the sea unchanged. I will, 
however, not dwell upon these mutual chemical decompositions and combinations, 
which, partly depending upon organic life, partly upon inorganic mechanical and che- 
mical forces, play such a great part in the changes of the earth, but I hope at some 
future time to find leisure to publish my investigations in this branch of the history of 
the earth. 
The elements which hitherto have been found in sea-water are, — 
1. Oxygen . — Besides that oxygen which is a constituent part of water, and other 
compounds that occur in the sea, such as the sulphates, phosphates, carbonates, and 
silicates, it occurs in a free uncombined state, absorbed by the water itself. It plays a 
very material part in the small but constant changes which take place in the sea- water, 
and whose general effects are that the organic substances dissolved in it are changed 
into carbonic acid and water. This effect takes place principally near the surface, and 
decreases with increasing depth ; and water from the deeper parts of the sea is able to 
destroy the colour of a greater quantity of the hypermanganate of potash than that from 
the surface, which again shows that there is more organic matter undestroyed in the 
deep sea. 
2. Hydrogen . — Besides the hydrogen which belongs to the composition of water, it 
occurs in the organic substances and in the ammonia which are dissolved in sea-water. 
3. Chlorine . — Next to the elements of water chlorine is the element which occurs 
in greatest quantity in sea-water, and has from the earliest times been recognized as 
such. 
4. Bromine has been long known as an essential part of the sea, easily recognized in 
the residue from the evaporation of sea-water after the crystallization of the greater part 
of the chloride of sodium. 
5. Iodine . — This substance is well known to have been the first element in sea-water 
discovered not directly, but by the analysis of the ashes of fucoidal plants, which by 
organic power had collected and concentrated it from sea-water. 
6. Fluorine . — Dana long ago showed that fluorine occurs in the lime of corals, where 
2 f 2 
