SALT WATER
“The new sight, the new wondrous sight,
The waters around me turbulent.”
E. B. BROWNING.
“Water, water, everywhere,
And not a drop to drink.”--S. T. COLERIDGE.
The annual stampede of Britons to the coast says much for our National
belief in Sea-breezes. In other countries also people go to the sea for
change; but perhaps nowhere does the rush excel that on our Island.
This revivifying gift, though partly due to the wide and free expanse
through which the breezes have travelled, is largely owing to the briny
ocean with which they have been in contact.
Sea-water differs from rain-water, well-water, river-water. True, it is
made up of all these, since sooner or later and in one mode or another
all water on Earth finds its way to the Ocean. Water may travel openly
by river-routes; it may creep silently by dark and devious underground
passages; it may float lightly _viâ_ cloudland; but in any case its
goal is the sea.
Still, though the ocean includes in its composition every kind of
land-water, Sea-water as such is different from them all. Not only in
its vast extent, in its enormous depth, but in its strong flavour of
Salt.
One of the commonest of substances is Salt. It is in the ground, in
air, in water. We even know that it does not belong to our earth alone,
but to many heavenly bodies also.
Perhaps one reason for this abundance, at least upon our Earth, is
that it is necessary for life. There is salt in the make of blood and
of brain, of muscle and of tendon. Salt is perpetually passing out of
a man’s body; therefore continual fresh supplies of it are needed.
Without a certain amount of salt in his food, he cannot keep in good
health.
This at one time was not understood; and salt was looked upon as a mere
luxury, easily to be dispensed with. Condemned criminals were forbidden
that luxury; and they went through a good deal of suffering, the reason
for which was not guessed. If plenty of animal and vegetable food was
given to them, they managed to get along, since both contain salt; but
if they were kept on purely farinaceous fare, they broke down.
Where all the salt in the Ocean comes from, is a complex question.
Large supplies are brought down annually by rivers and streams, from
various minerals in their beds, as well as from rock-salt regions. But
if we ask, “How comes the rock-salt to be there?” we are told that it
is a deposit, once formed beneath ocean-waters, or at least left by
the drying up of salt lakes and seas. A proof of the latter theory is
found in multitudes of sea-shells, often distributed through layers of
rock-salt.
If much sea-salt came originally from rock-salt on land, and if
rock-salt came originally from ocean-deposits, we are led into a
curious circle of cause and effect--not unlike that of oak and acorn,
or of hen and egg, with the attendant puzzle of--Which first? It is a
query which we are not able to answer.
In former days the salt used for household and mercantile purposes was
almost entirely prepared by the evaporation of sea-water. We no longer
depend on this, however; and in England the sea-salt trade has gone
down greatly before that of rock-salt, which is found to be the better
for table use. It has not the same tendency to stick together in
lumps, after being packed in sacks.
Great districts of rock-salt are found in many places--such as those
in the Carpathian Mountains, in the Swiss Alps, in Germany, and in
Great Britain. One huge mine in Galicia has been worked for six hundred
years; and this supply is said to reach through about five hundred
miles. From British works alone the quantity carried away every year
amounts to a cubic mile of salt.
But land-supplies grow pale and insignificant before the quantities
which float in the ocean. It has been reckoned that, if the waters of
the whole ocean could be dried up, the amount of salt left lying on the
ocean-bed would be something like four-and-a-half millions of cubic
miles.
Such an enormous mass hardly conveys a clear idea. Let us think of one
single cubic mile of sea-water, separated from the ocean, and see how
much it would contain. First, the whole of that cubic mile of water has
to be dried up; and then the materials left behind have to be weighed.
We should find about thirty-three millions of tons of various kinds
of substances, the names of which need not be given. We should also
find of common salt a supply which, when weighed, would reach the great
figure of _one hundred and seventeen millions of tons_. All this, be it
remembered, floating unseen in a single cubic mile of water. No wonder
the sea tastes salt.
In its make Water is always the same. Whether it be cold or hot,
freezing or boiling, causes no difference. It consists of two gases,
united; and the union is remarkable in kind. The two gases are not
merely mixed together, as sand and sugar may be mixed. They are by the
union changed into a fresh substance. For the time the gases exist no
longer. In their stead, water has been formed.
And when the gases enter into this very close relationship, they do it
always in the same manner. There is just so much of the one, and just
so much of the other. One portion of hydrogen has to join with eight
times as much by weight of oxygen--neither more nor less of either. The
same is true, whether we are speaking of a great mass of water, or of
the tiniest speck.
It is not actually correct to say, as is said above, that water
“consists” of the two gases. So long as the water exists, the gases do
not exist. And when, through the action of heat or electricity, the
water is broken up and the gases reappear, then the water no longer
exists. But at least we may say that it is the result of the uniting of
those two gases, and that it can be made in no other way.
An interesting experiment has been tried. A certain amount of hydrogen
gas and eight times as much of oxygen gas were weighed separately, by
means of very delicate instruments. Then through great heat the two
were caused to unite into water, and the water also was weighed. It
was found to be just as heavy as the two gases together had been; and
quite naturally so, since neither of the two gases had lost or gained
in weight. This kind of union is called “chemical.”
French people are fond of “eau sucré.” A lump of sugar is dropped into
a glass of water, and it disappears. But it has not been destroyed.
It has not ceased to be sugar. No mysterious union has taken place
between the sugar and the water. Neither water nor sugar has changed
its nature; and no fresh substance has come into existence in their
stead. The water is there, as it was before. The sugar is there too,
not visible, but to be found out by our sense of taste. It has only
been separated by the water into such minute particles that we cannot
see them. This is a case of mixing, not of chemical union.
When we think of the characteristics of Sea Water, as compared with
Fresh Water, we have to do with simple mixing. As sugar floats, unseen
but not untasted, in tea or coffee; so salt floats, unseen but not
untasted, in ocean waters.
Such a thing as absolutely pure water is very rare. No matter how clear
a stream may seem to us, it holds a vast number of specks of material,
collected from earth and air. Once a scientific man had some, most
carefully distilled, which seemed to be of crystal purity. But he put
it under the strong beam of an electric lamp, and, alas, for human
powers! after so doing he could only declare that the idea of purity
was ludicrous. If it is so with distilled water, the less said the
better about common drinking-water. It may be well for our peace of
mind that we have not stronger sight.
Ocean-water holds about two hundred times as much dissolved material as
ordinary fresh water. The different kinds of substances found in any
particular water-supply determine the character of that water, making
it sweet or sour or salt, rendering it health-giving or death-dealing.
Something has been said about the drying away of sea-water, and the
leaving of salt behind. A remarkable instance of salt thus left is seen
in the Rann of Cutch, a flat Indian plain, about a hundred and ninety
miles long, and half as wide.
During the south-west monsoon the ocean waters are forced by powerful
winds up the Gulf of Cutch to a considerable height, overspreading the
Rann, which for a time is turned into a shallow lake. When dry weather
comes, the water vanishes, partly retiring, partly evaporating; and a
salt-strewn desert is left, varied by sand-ridges, green spots, and
little lakes, but covered principally by “sheets of salt crust.” My
father, when there many years ago with his Regiment, noted down his
impressions of the scene.
“From this spot”--the spot on which he stood--“the water is about eight
miles distant, the intermediate space being a flat surface, entirely
covered a quarter of an inch thick with salt in crystals, looking much
like snow, in such quantities that it can be scraped up by the hand
perfectly free from earth; and on all this space not a blade of grass
to be seen.”
The same task is carried on by the working of sun-heat, as by the fire
under a kettle. All day long in a warm climate the sun’s rays are
busily at work, lifting from the ocean-surface a continuous stream of
fine invisible vapour. The water is drawn up particle by particle, not
in masses; and the sun’s rays have no power to lift the ocean-salt,
which remains behind, floating still in the sea.
But when a strong wind lashes the surface into waves, and rends the
tops of billows into fine spray, it often carries a great deal of salt
to a distance. We know how salt may be tasted on the lips miles inland,
and how windows near the coast become encrusted with it in stormy
weather. Moving air, like moving water, can carry weight; and it is
thus, through the action of moving air, and not through the heat of the
sun, that we have our health-giving breezes off the sea, laden with
salt.