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PROFESSOR FORCHHAMMER ON THE COMPOSITION 
than my observations, but I trust that it will not make my work superfluous, but that 
both these investigations will supplement each other. By the kindness of Admiral 
FitzRoy I am able to compare the instruments which are used by the British Navy with 
my chemical analyses, and thus to obtain a comparison between both series. 
I have at different times found an opportunity to publish several parts of my obser- 
vations, and in 1859 I collected what had been done up to that time in an academical 
treatise in the Danish language*. Since that time I have obtained numerous samples 
of sea-water, principally from places which my previous examination had not reached. 
In this new form, and greatly augmented by new facts, I permit myself to lay it before 
the illustrious scientific society of a nation to whose navigators I owe so great a part of 
the material for my inquiries. This part contains an enumeration of the elements which 
hitherto have been ascertained to exist in the water of the ocean, and an explanation 
of the methods used to show their presence and to determine their quantity. It con- 
tains a determination as complete as possible of the distribution of the saline substances 
at the surface of the different parts of the sea, and in the different depths at the same 
place. 
On the Elements which occur in the Water of the Ocean. 
The elements which occur in greatest quantity in sea-water have been long known, 
and chlorine, sulphuric acid, soda, magnesia, and lime have for more than a century 
past been considered as its essential parts. In our century iodine, bromine, potash, 
silica, phosphoric acid, and iron have been discovered in sea-water, and the latest 
inquiries, my own included, have brought the number of elements occurring in sea-water 
up to twenty-seven. 
Next to direct analyses of sea-water, the analysis of sea-weeds, and of animals living 
in the sea, offers us precious means of determining those elements which occur in so 
small a quantity in sea-water, that it hitherto has been impossible to ascertain their 
presence in the water by chemical tests. It is now well known that the organic beings 
collect substances which are necessary for their existence, and thus offer the means to 
the chemist of ascertaining that these Substances were present in the medium in which 
the organisms lived, and from which they collected their food. As to the plants of the 
sea, the whole fucoid tribe derive the substances of which they consist from the sur- 
rounding sea-water and from the air with which they are in contact, but not from the 
soil on the bottom of the sea, since that part of them which generally is called their root 
is no root at all, and is not qualified to extract food from the soil and stones to which 
it adheres. Even those marine plants which do not belong to the fucoid tribe, as, for 
instance, the Zostera marina , and which have a real root, that may extract food from 
the soil, will most probably extract the great quantity of mineral elements which they 
contain mostly from the surrounding sea-water. As to the animals that live in the sea, 
they derive their substance either from the sea-water itself, or from plants that are 
* Om Soevandets bestanddele og deras Fordeling : Hayet. af G. Forchhammek, Professor ved Kjobenhavns 
TJniyersitet. 
