19s Dr. Marcet on the specific gravity and temperature 
difficulty, and indeed the impossibility, of analyzing complex 
solutions of saline substances with a view to obtain a precise 
and certain knowledge of the state of combination in which 
the salts exist in these solutions, I contented myself with as- 
certaining, first, the proportions of saline matter yielded by a 
given quantity of each water, and afterwards, the proportions 
of acids and earths contained in these respective waters ; 
thus presenting data which are quite divested of theoretical 
views, and from which the composition of those waters may 
at any time be inferred in the way which may be deemed 
most eligible. 
It has been long known that the principal salts contained 
in sea water are muriate of soda and muriate of magnesia, 
and that it contains also sulphuric acid and lime. But whe- 
ther these ingredients existed in the form of sulphate of 
soda, or of sulphate of lime, or muriate of lime, or sulphate 
of magnesia, was more or less a matter of conjecture, as the 
different states of binary combination which they assume, 
are modified during evaporation by the different degrees of 
solubility which the salts possess, and are liable to be in- 
fluenced by heat and concentration, the very processes which 
are used in attempting to resolve the question. These diffi- 
culties have been ably discussed by Dr. Murray,* whose 
reasonings and experiments on the subject have given great 
plausibility to the doctrine which he has proposed, according 
to which the salts contained in sea water are supposed to be : 
River Jordan;’ Philos. Trans. 1807. And ‘ An Analysis of an Aluminous Chaly- 
beate Spring in the Isle of Wight Geolog. Trans. Vol. I. 181 1. 
* See ‘An Analysis of Sea Water’ read in 1816, and published in the Edinburgh 
Transactions, Vol. VIII. and also a ‘ Formula on the Analysis of Mineral Waters,’ 
printed in the same volume. 
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