348 On the Proportion of Fluoride of Calcium 
therefore, state as the result of direct examination of de- 
posits which may be fairly taken to represent the following 
waters, that fluorine is present in the Friths of Forth and 
Clyde, the German Ocean, the Trish Sea, the Atlantic, and the” 
Mediterranean ; and Professor Forchammer bears testimony * 
to its presence in the Baltic. We may, therefore, infer, that 
as the sea within narrow limits is very uniform in chemical 
composition, fluorine will be found universally present in the 
ocean. Indirect proof of this has already been derived from 
the presence of fluorine in corals and-shells, as well as in 
marine fishes and mammalia.* My present object, however, 
is to refer solely to the results obtained by a direct analysis 
of sea-water. 
Professor Forchammer’s letter is as follows— 
COPENHAGEN, 20th December 1849. 
Dr GEORGE WILSON, 
My DEAR Si1r,—Enclosed in this letter you will find 
an abstract of a paper which I have been preparing for the 
Royal Society at Copenhagen, and which I hope soon to be 
able to have published. It contains experiments on many 
other substances contained, in minute quantities, in sea-water, 
for instance, manganese, ammonia, baryta, or strontia, be- 
sides iron and silica, which occur in proportionally large quan- 
tities.—Believe me, my dear Sir, yours, 
G. FORCHAMMER. 
Abstract of a Paper by Professor Forchammer, on the Rarer 
Substances which occur in Sea-Water. (To be read at the. 
Royal Society at Copenhagen.) 
Fluorine and Phosphoric Acid. 
100 Ib. of sea-water as it occurs in the Sound, near Copen-. 
hagen, of which the average quantity of salts is between 2 per. 
cent. and 23 per cent., was evaporated. _When the solution: 
was so concentrated that it began to deposit salt, it was, withs» 
out filtering it, mixed with an excess of ammonia, and the pre- | 
HT 
acid before it can act on the glass. The Atlantic and Mediterranean crusts, 
were of this description, and etched more readily than the Irish crusts, which 
abounded in chlorides. 
%* Edin. Royal Soc. Trans., Vol. xvi., Part il., p. 155. N38y4 
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