361 
Dr Marcet’s Experiments on Sea-Water. 
The greatest difference found by Lieutenant Parry was 6°, at 
a depth of 246 fathoms ; and the greatest obtained by Captain 
Sabine was. 71°, at a depth of 680 fathoms. 
By cooling sea-water with freezing mixtures, and ascertaining 
its specific gravity at each degree of temperature, as it ap- 
proached congelation, Dr Marcet found, that the law of maxi- 
mum density at 40° did not prevail in the case of sea-water ; but, 
on the contrary, sea-water gradually increased in weight down 
to the freezing point. This able 'chemist confirmed this re- 
sult by means of an ingenious instrument, with which he 
measured the bulk of the water under various temperatures. 
The water was always^found to contract in bulk down to 22® of 
Fahrenheit, when the water appeared to expand a little, and 
continued to do so till its temperature descended to between 19° 
and 18°, when the fluid suddenly expanded to a very consider- 
able degree, shooting up with great rapidity, and forcing itself 
out of the open end of the tube. At the same moment the 
thermometer rises to 28°, and remains at that point. The liquid 
is now found frozen, and in a few minutes the maximum of ex- 
pansion is obtained. 
Dr Marcet next proceeds to ascertain the saline contents of 
the different seas ; and in this investigation he employed a me- 
thod which he had long ago used and explained in his analysis 
of the Dead Sea, published in the Phil. Trans, for 1807. It 
is satisfactory to observe,” says Dr Marcet, that Dr Murray 
adopted, several years afterwards, a mode of proceeding precise- 
ly similar, and indeed, that he proposed, in a subsequent paper, 
^Edin. Trans. 1816, Vol. viii.) a general formula for the ana- 
lysis of mineral waters, in which this method is pointed out as 
likely to lead to the most accurate results. And this coinci- 
dence is the more remarkable, as it would appear from Dr 
Murray not mentioning my labours, that they had not at that 
time come to his knowledge.” All the results which Dr Mar- 
cet obtained by this mode of investigation prove, that sea-water 
contains the same ingredients all over the world, and that these 
bear very nearly the same proportion to each other, differing 
only in the total amount of their saline contents. 
The following table contains all the results obtained by Dr 
Marcet. 
VOL. II. NO. 4. APRIL 1820. 
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