388 CONSTITUENTS AND SPECIFIC GRAVITY OF THE BALTIC. [Chap.XXl
influenced by the direction of the wind. The following are the results
which he obtained:
Wind at east ............ 1*0039
Wind at w e s t ........... 1*0067
Storm at west ......... r o i 18
Wind at north-west .............. 1*0098
From the great effect o f the wind one would be tempted to suspect
that the place o f the Baltic from which he took the water that he examined
was pretty far to the south; but that does not agree with the
first specific gravity which he found, and which is lower than that of
the water taken up by me at Tunaberg. It is proper to state that I
took up the water which I examined in calm weather, and there had
been no violent winds for at least a month. So that I consider the results
which I obtained, as yielding a pretty fair mean of the contents of
the Baltic at the different places examined.
One thousand grains o f each o f these waters were evaporated to
dryness at a temperature which never exceeded 180°, and the dry residue
was kept for eight hours in the temperature o f about 200°, by
means of a steam-bath, and then weighed. The weights o f the salt
furnished by each specimen are as under:
Weight of salt.
Water of the Frith o f Forth........................... 36*6
Water from Tunaberg . . . . ........................... 7-4
Water from the Sound ........... 11*2
Water from the Scaw . . . . . . . . . . . . . . . . . . . 32*o
From this table we see that the Baltic at Tunaberg scarcely contains
one-fifth part o f the saline contents o f the ocean which surrounds
Great Britain. The water at the Sound contains rather less than one-
third, and the difference between the water of the ocean and that at
the Scaw, though less, is still very considerable. I f we reckon the
salt contained in the Baltic, at Tunaberg, 1, the following table exhibits
Chap. XXI.] . CONSTITUENTS AND SPECIFIC GRAVITY OF THE BALTIC. 3 8 9
the relative proportion -of salt contained in- the water taken up at
other places:
Water from Tunaberg............................ l*ooo
Water from the Sound .................. 1*513
Water from the Scaw................. 4*324
Water from the Frith o f Forth ................ 4*945
The water at Tunaberg tastes slightly brackish, but is so little so
that it may be drunk without much inconvenience. And I have been
told by the sailors that they commonly use the water o f the Baltic for
their food. The water at the Sound is perceptibly salter, but still not
disagreeably so. But the water off the Scaw tastes as salt as the water
of the Ocean itself.
. I analysed a quantity of the salt obtained from the water taken up off
the Scaw, by methods well known to chemists, and which it is unnecessary
to detail here. The following was the result which I obtained.
It may be considered as exhibiting the constituents of sea
water in general, for I presume it will hardly be doubted that the por-
portions are every where nearly the same :
Common sa lt...................................... 55*7
Sulphate of magnesia ...................... 25*0
Muriate o f magnesia.......................... 19*3
1000
I have reason to believe that there exists likewise in sea-water a portion
of sulphate o f soda. I have not indeed been able to separate any
such salt; but I find always a surplus o f sulphuric acid which must be
United to some alkaline body. Sulphate of lime is likewise present;
but in so small a quantity, that in a general view of this kind it may
be omitted altogether.
Thus the Baltic sea differs entirely in its constitution from the water
of the Ocean, containing much less salt, and diminishing in saltness as
we advance northward. I f the same rate of diminution which I ob