There are men, called chemists, who know a great deal concerning the
nature of different kinds of substances, and who, in consequence of
this knowledge, are able to bring about very surprising changes and
effects. These men have places, termed laboratories, or labor shops, in
which they work, and which are divided into distinct chambers, besides
being furnished with all sorts of instruments and vessels. Sometimes
liquids are put into these chambers and vessels, and there turned into
solids. Sometimes both liquids and solids are converted into invisible
air. Sometimes beautiful crystals, white and blue, green and red,
are brought out of transparent and colorless fluids. Sometimes a few
grains of dusty looking powder are made to vanish into smoke with an
explosion that shakes the ground for yards; and sometimes waste rubbish
is transformed into delicious scents, resembling those which are
produced from the violet and the rose. Even dull, black charcoal has
been changed into the sparkling and precious diamond. It would require
a very large book merely to number the wonderful feats these men of
science are able to perform. Chemists, indeed, in the present day can
do much more by their knowledge and skill, than magicians pretended
they could accomplish in the olden time.
Chemists make use of many very powerful agents in their laboratories,
to aid them in carrying out their objects and plans. Among these agents
there are two that stand before all the rest both in strength and in
general usefulness. These prime assistants of the chemists are fire
and water. The water is employed to dissolve substances whose little
particles it is desired to bring closely together. When two different
liquids thus formed are mixed, all the particles in the two come
together and act upon one another. Fire is used to soften substances,
and loosen the hold of their little particles upon each other, so
that they may afterwards be readily mixed together. Water _dissolves_
bodies; that is, makes them liquid by uniting them with itself. Fire
_melts_ bodies; that is, makes them liquid without the aid of water.
Now there is one object which the chemists often have in view, when
they put different kinds of substances together, in a dissolved or
liquid state, in the chambers and vessels of their laboratories; that
is, to get something out of those substances, which was before hidden
away in them, in order that they may turn that something to practical
use. Thus the chemist mixes together saltpetre, sulphur, and charcoal
in the right proportions to make gunpowder. Then having rammed a charge
of the gunpowder down into the tube of a gun, with a bullet on the top
of a charge, he applies a spark to the gunpowder, and makes it change
into smoke and vapor. Something which was hidden away in the gunpowder
ceases to be concealed when it is changed into smoke and vapor, and
becomes active enough to be able to drive the bullet out of the muzzle
of the gun with a force that carries it through the air for a mile, and
perhaps then buries it deep in the ground, or in a plank of wood. This
is an instance of the way in which chemists produce motion, by changing
the state and condition of material substance.
I had occasion the other day to watch a still more interesting
example of this strange result of the chemist’s skill. In a chemist’s
laboratory, prepared for a particular service, I saw several small
chambers of metal, half copper and half zinc, into which were poured
blue vitriol and water, and an acid, a partition wall of pipe-clay
standing between. The dilute acid and the zinc were slowly turning into
white vitriol, which remained dissolved away in the water; but out of
this new-made white vitriol there flowed a power, which was conveyed
along a wire, and which made a needle, hung up on a pivot before me,
twitch from side to side, almost as if it had been a living thing. I
was told that this power set free in the solution, in consequence
of the changes brought about there, would run along the wire to the
distance of a hundred, or even of a thousand miles, and would there
make another needle work and twitch in the same way. In short, I was
looking at the electric telegraph at work, and learning that the agent
which made the signal afar was simply a power that had been hidden
away in the different substances the chemist put together in the
metal chambers, and that was set free and enabled to operate in the
production of independent motion, so soon as those substances acted
upon one another, and altered the form and state in which each was
existing.
Now, my good friend, your living body, and my own, are laboratories, in
which changes of precisely the same kind are constantly brought about;
your living body, and my own, are made of an enormous quantity of
separate chambers and vessels, very small, it is true, but nevertheless
such as can be seen quite distinctly when they are looked for with the
microscope. In these small chambers and vessels different kinds of
substances are thrown together, exactly as the zinc, and acid, and blue
vitriol are in the laboratory-chambers of the electric telegraph. The
chambers and vessels of the living laboratory lie between meshes of
the supply pipes of the body, and it is indeed their minute cavities
which are drenched by the circulating streams of the dissolved food
(see “Value of Good Food”), and in which that dissolved food gets to
be transformed into flesh and fat, gristle and bone, tendons and skin,
fibres and nerves. The blood, which is pumped forth with such vigor
from the heart, creeps along slowly through the smallest and furthest
branches of the supply-pipes, in order that plenty of time may be given
for all these changes to be worked out in the chambers of the frame.
But the fibres and skin, the flesh and the nerves, when they have been
built up, are also changed into waste substance by admixture with yet
other ingredients which the blood brings to the little chambers. In
the cavities of the living laboratory, as in those of the electric
telegraph, these changes of substance lead to the setting free of
agents before concealed, which agents then operate in the production
of movements and of other living effects. When I now raise my arm up
above my head, I am able to do so because some of the flesh of which
my arm is composed, is changed into another kind of substance, the
moving power being set free during the change. When I feel this hard
stone which I take up in my hand, I am able to do so because some of
the substance of which my body is made, is changed into another kind of
material at the instant that I feel. This, then, is how strength comes
out of food. The food is changed into flesh, and the flesh is converted
into two distinct parts, waste substance and moving and living power.
The power was originally concealed in the food, placed there by the
provident hand of the Divine Author of Nature, in order that it might
be forthcoming for this useful service when it was required. In simple
words, material substance is destroyed in order that power may be
extracted from it. Material substance, in living bodies, is turned into
power. This is the mechanism by which God works in these, the most
wonderful of the productions of his hands.
It will hardly be necessary, after all that has been already said
elsewhere, to point out that the prime assistant of the chemist, water,
acts in the living laboratory exactly as it does in the artificial
ones. It loosens, dissolves, and mingles together the various
substances which are to act upon one another. It is in the dissolved
food, and the liquid blood, which flow into all the chambers and
vessels of the living body, and which build up in them the fibres of
living structure, and then transform and destroy those fibres, in order
that the power there stored away may be obtained.
But it is still more remarkable that the other prime assistant of
the chemist, fire, should also be employed in the living frame, in
loosening its particles, and in quickening the operation of the various
changes of substance upon which the production of power depends. It has
been shown that in the body of a full-grown man there is as much heat
produced in a single day, as would serve to make eighty pints of cold
water boil, and it has also been stated that this heat is produced in
the body exactly in the same way heat is produced in the steam engine;
that is, by the burning of fuel. The heat is set free by the change of
condition in material substance, precisely as power is procured. When
the water employed in a steam engine is made to boil, the heat that
causes the boiling issues from the coal, because that substance ceases
to be coal, and turns into smoke and vapor. Just so the fuel substance
of the body ceases to be fuel substance, starch, sugar, and fat—and
turns into vapor, which is steamed away, leaving the heat which was
concealed in the substance to warm the frame.
The furnace which is kept burning in the living laboratory, to quicken
all the operations which are being carried forward in it, and to
furnish its strength, is a slow and gentle one. It never burns quickly
enough to cause light and flame, as common fires do. The body is never
even raised to the heat of boiling water, which is far less than that
of burning coal. It is only made of blood-heat; that is, sixty-eight
degrees of the heat-scale warmer than freezing water,—in its warmest
parts. Boiling water is one hundred and eighty degrees of the same
heat-scale warmer than freezing water. The furnace of the living body
sometimes burns a little more quickly than it ought, then the body gets
warmed into fever. Occasionally it burns considerably less quickly than
it ought, then the body is chilled, and its living actions and powers
are slothful and languid. Upon the whole, however, its heat is steadily
kept up at pretty much what it ought to be, that is, at one hundred
degrees of the scale, which gives thirty-two degrees for frost.
Now this is how the furnace of the living body is kept smouldering on
in its gentle and even way. Little blasts of air are constantly puffed
in upon the burning fuel. That out-and-in play of your chest as you
breathe,—that is the puffing of air blasts into certain chambers of
your living laboratory, to keep up its smouldering fires. The more
quickly and deeply you breathe, the warmer your body becomes; and the
more slowly and softly you breathe, the colder that body remains. The
same action which blows a fresh wind through the living frame to clear
away its impure vapors, also serves to fan its hidden flames, and keep
its fuel burning. When the breathing is stopped the fires of the body
go out, just as those in a common furnace do, when their air-blasts are
arrested, and the body becomes dead cold.
You will remember that when the fresh air is drawn into your lungs
as you breathe, it enters a large quantity of little cavities or
chambers, which have, all of them, a fine net-work of the supply-pipes
stretched out upon their walls; and that as the blood rushes on in its
course through these supply-pipes, it sucks air into itself from the
air-cavities, and carries it, in its own streams, to all parts of the
living structure. Air goes with the blood to that strong force-pump,
the heart, and is then pumped out with the blood to every crevice and
fibre of the body. Every part of the body therefore receives, by means
of the supply-pipes and in the blood, heat-fanning air, as well as
supporting food.
When air reaches the living flesh and nerves, by thus flowing to them
in the blood-streams of the supply pipes, it sets up those changes
of substance in their structures which lead to the production of
movement, and feeling, and other kinds of living power. When it reaches
the dissolved fuel, contained in the blood and in the various little
furnace-chambers of the laboratory, it sets up those changes in the
fuel which lead to the production of warmth. The fuel is slowly burned
in the blood and in the chambers of the frame, and there gives out
warmth, as a fire does whilst it is burning in a grate. This warmth
consequently heats the blood, and the warm blood carries its heat
wherever it goes. The entire body thus becomes as warm as the blood, or
nearly so.
Now, where do you think all the heat originally comes from, that is
procured from burning fuel? The heat is stored away in the fuel, as
one of the ingredients of its composition, until it is burned. But
where was the heat obtained from, which is stored up in the fuel? Of
course, when the fuel was made, that heat-store had to be supplied to
it, as well as its other ingredients. First let us see when and how
the fuel was made, and perhaps we shall then be able more perfectly to
understand this matter of its warming qualities and power.
In the case of coal, it is not a very difficult task to trace the
stored-up heat to its source. But what a surprising truth it is, which
becomes apparent when the task has been performed. The heat is, so to
speak, _bottled-up sunshine_! Coal is dug up from deep mines hollowed
out in the earth. But at one time it was wood, growing on the outer
surface of the globe, and covered with foliage which was spread out
into the genial air. Traces of the leaves and stems from which it
has been made, are still discovered in its substance. Long centuries
ago, the vast forests containing these trees, were overthrown by some
tremendous earthquake, and swept away by strong floods of water, and so
the tree-stems were at last deposited in hollow basins, and were there
buried up by millions and millions of tons of heavy rock and soil.
There, where they were buried, they have remained, turning more and
more black and dense through the process of slow decay, until they have
been dug up piece-meal to feed the furnaces and fires of the existing
generation of men.
Now, you know very well that trees only grow in warm weather, and in
sunshine. In winter time their branches stick out stiff and bare, and
do not increase in the slightest degree. But in summer time they clothe
themselves with beautiful masses of foliage, and suck in from both the
air and the soil large quantities of vapor, of liquid food, and of
sunshine. All these they combine together into fresh layers of timber.
All these therefore were buried in the ground as timber, when those old
forests were overthrown which form the coal-beds. Timber cannot be made
in cold weather, because heat is one of its necessary ingredients. But
as all the warmth of the weather comes from the sun, it is the sun’s
warmth which is stored away in the coal, and which is set free and made
useful when the coal is burned.
The grand source of all warmth on the earth is that brilliant light
which God has placed in the sky to rule over the day. In a summer’s
day you sit down in the bright sunshine, and bask in its warmth.
In winter time, when the sky is covered with clouds, and ice and
snow lie thick over the ground, you place yourself indoors near the
glowing fire; but strange to say, it is still the sun’s genial warmth
that you experience. If the fire be of coal, it is warmth which was
borrowed from the sun centuries ago. Reflect for an instant upon this
marvellous arrangement entered upon, for your comfort, ages before you
were yourself called into being! When those coal-making forests spread
their broad masses of foliage out in the sunshine, there were no human
creatures existing upon the earth; and, indeed, not even the flocks
and herds, which are so essential to man’s welfare, had been framed.
Neither cattle nor sheep could have found pasture on the plains which
yielded them support. The great duty of those forests must have been to
store up genial warmth for then uncreated generations of beings, who
in due season were to appear, and to avail themselves of the provision
thus made.
But suppose that you had neither fresh nor stored-up sunshine to fall
back upon, and had to depend entirely for your warmth upon that furnace
which is carried about in your living laboratory, and kept alight by
the puffing of your breath. Still that internal heat comes originally
out of the sunshine. Just before the time when man was placed upon
the earth, the beautiful family of plants was created, which fills
the gardens with roses, and which yields the apple, the pear, the
cherry, the plum, the apricot, the peach, the almond, the strawberry,
and the raspberry. Just at the very time was planted on the globe,
the vegetable tribe which furnishes the different kinds of nourishing
grain, and which provides pasture for grazing animals. The fruits,
the grasses, and the grain were all commissioned to extract power and
warmth from the sunshine, and to store it up in such a form that the
influences could conveniently be introduced into the interior of the
living body. Living animals which are warmed by the fuel contained in
their food, procure their heat from sunshine that was stored up, as
it were, but yesterday. When animals live upon flesh, and get their
strength out of the lean fibre, and their warmth out of the fat of
this food, still it must be remembered that the flesh has been fed on
the grass of the field just before. The main office of the plant in
creation is thus to store up in a fixed and convenient form supplies
of active energies which can be turned to account by animated frames.
The plant effects this end by preparing the food upon which animals
live;—that food which, besides keeping the body in repair, serves also
to furnish it with warmth, and to give it strength and power. How
admirable and beneficent is this plan, whereby the genial influence of
life-quickening sunshine is economized and preserved for the service of
one-half of creation, by the instrumentality of the other half!
In the far distant regions of the north, there are places on the earth
to which no daylight or sunshine comes for four long months at a time.
During this gloomy period the ground goes on, from hour to hour,
scattering more and more of its heat, until it is almost as cold as the
chill space in which the great world is poised, and has indeed more
than 100 degrees of frost. The land and the water alike get covered up
by one broad and thick sheet of never-melting ice and snow. There is
not a leaf, or a grass blade, or a vegetable stalk any where in the
wide white desolation. But there are animals and human beings, who are
born and die, who maintain a prolonged existence in it. Let us just
look in upon one of the households in this drear frost land, and see
what the odd community is like.
In the midst of a broad snow waste, through which the sharp wind is
howling with a fearful sound, there is a small mound nearly covered by
the snow-drift. We perceive this mound by faint starlight, the only
gleam that comes down from the sky. A few feet away from the mound we
discover a small hole blocked up by a lump of snow. We move the lump
aside, and stretching ourselves out at full length on the ground, we
squeeze into the hole head foremost, and crawl along a narrow passage,
burrowed out in the firm snow for about a dozen feet. We then find
ourselves in a vault ten feet wide and fifteen feet long, and so low
that we can scarcely sit upright within it. This is the inside of the
mound. It is the interior of a hut, or dwelling-place, of these people
of the drear frost land. The walls of the hut are built of large stones
piled together, with a padding of frozen moss covered over them, and
with thick ice and snow covered over the moss.
There are twelve living individuals, men, women, and children, huddled
together in this close vault. They have no fire to keep them warm.
Indeed, there is neither coal nor wood which they could use to light
a fire, within many hundred miles. There is in one corner of the hut a
broad shoulder-blade of a large quadruped laid flat, and in the hollow
of this blade there is some crushed seal’s blubber, and some soft moss,
with long cotton-like rootlets. The end of the moss is burning with a
small, dull, smoky flame. This is the only artificial source of light
and warmth within the hut.
But these people are all of them almost entirely naked; and they are
dripping with perspiration, they are so warm. Outside of the hut, in
the dim starlight, the air is actually a hundred degrees colder than
freezing water. Yet inside, in the nearly as dim lamp light, there
are almost as many degrees of warmth. The air is there as hot as the
hottest summer day in England! All this heat is produced in the slow
furnaces of those twelve individuals’ own living bodies. They have lost
the sunshine for months, and everything around them is much colder
than ice. They are living upon the flesh and blubber of seals, and
sea-horses and white bears, animals which they killed before the sun
went away, the meat being kept for them through their long winter by
the preserving power of the frost. The sunshine of past away summers
has given its heat to plants; the seals and sea-horses have fed on
those plants, or upon smaller animals which have done so, and have
transferred the heat into their own blubber; and now the benighted
savages are getting the heat out of the blubber to keep their own flesh
and blood warm and unfrozen. In that close hut, where no sunshine can
come for months, the savage inmates have nevertheless abundant stores
of the warmth of sunshine, which have been laid up and preserved for
their service. Such care Providence takes even of these, the rude and
barbarous children, whose lot he has cast in the desolate outskirts of
the world!
The rude people who dwell in the cold frost-land of the north, remain
warm through their long, severe winter, without the aid of artificial
fires, because they economize the warmth which is produced in the slow
furnaces of their bodies, and prevent it from being scattered away as
quickly as it is generated. If they were to set themselves down in the
open air, instead of in their close huts, the warmth produced in their
bodies would be thrown off from the outer surfaces of these as fast as
it was set free from the fuel. In the close huts, on the other hand,
this warmth first heats the air contained within the stone walls, and
is then a very long time in getting any further, and so prevents more
heat from being rapidly scattered from the internal furnace.
These human inhabitants of the northern ice land have a companion in
their desolate haunts, who does not build himself a hut after their
fashion, but who has instead a somewhat similar protection against
the severe cold of the long northern winter, provided by nature. This
creature goes upon four legs, sometimes swimming in the water, and
sometimes stalking along upon the ice. He is very powerful and fierce,
is armed with sharp claws two inches long, and has teeth which can bite
through thick and hard metal. He is able to tear iron and tin to pieces
as if they were merely paper or pasteboard, and he feeds upon seals,
birds, foxes and deer, which he manages to catch by his cunning and
address. This savage creature is often killed by the rude natives, who
hunt him with dogs and spears, but in the absence of man he is the fell
tyrant of the domain. He prowls about on the snow-wastes, destroying
every living body which comes within his reach; and he remains exposed
to the severest cold of the long dark winter, lying upon the ice and
snow, without having his life-blood frozen by its chill power. The
reason of his safety is that he wears a nature-provided great coat of
very warm fur. His skin is every where covered by long shaggy hair of
a yellowish-white color, which has a thick down-like under-growth
closely packed beneath. This coat of soft fur is so long and thick,
that it prevents the heat produced in the slow furnace of his body from
escaping into the cold air. It answers the same purpose to him, that
the snow-covered hut does to his human neighbors.
Men have no warm shaggy coats of this kind furnished for their use
by nature, but they are enabled to supply the deficiency through the
exertion of their own intelligence and ingenuity. They borrow warm
covering from other creatures whenever they stand in need of such aid.
Thus the rude human inhabitant of the ice land hunts and kills the
bear and then before he feasts upon its flesh, he strips the fur robe
from the carcass, and adapts it to his own naked body. So soon as the
northern ice-people come out from their huts into the cold air, they
put on coats and trousers of bear-skin, with the long sharp claws
pointing out as toes to their boots. These odd savages look almost like
small bears themselves when their white fur hoods are drawn over their
heads, and their limbs are compactly muffled up in the claw-tipped
robes which they have taken from the bodies of their prey.
Men in civilized lands do not put the skins of other animals upon their
own bodies, but they do what is precisely the same thing in effect.
They borrow silk from the worm, or cotton from the grass, or flax from
the linen-plant, or wool from the sheep, and by their constructive
skill, they spin and weave these substances into cloths, which are
much more convenient than raw skins for the fabrication of garments,
and which can be made as warm, when this is required. In every case,
however, this artificial clothing acts in the same way as natural fur.
It is warm, because it prevents the heat, which is produced in the slow
furnace within the body from escaping quickly from the little chambers
of the living laboratory. Clothing does not really warm the body, it
merely keeps it warm; prevents it from being cooled as it would be if
this covering were not placed between its surface and the outer air.
Warm bodies constantly grow colder, when situated in spaces which are
more chill than themselves, provided always that there be no furnaces,
quick or slow, within them, for generating new supplies of heat. They
do so, because they give the excess of heat which they contain to the
neighboring space, in the attempt to make it as warm as themselves.
Warm bodies are always very generous, and disinclined to keep what
substances near to them are less freely supplied with. If a metallic
pint pot, filled with boiling water, be placed on the ground in air
which has only the warmth of a March English day—some fifty degrees
of the heat scale,—the water gets colder minute by minute until it
remains no warmer than the air and ground which are around it. The
rapidity with which warm bodies are cooled depends upon how much colder
than themselves the space around them is. If one pint pot of boiling
water be placed in out-of-door air that is cold as freezing water, and
another be placed at the same time in a room where the air has the
warmth of a mild summer day, the former will be deprived of all its
excess of heat much sooner than the latter.
Warm bodies lose their excess of heat in two ways. They shoot it off
into surrounding space. This is what learned men call “raying” or
“radiating” it away. The sun, you know, shoots or rays its heat off to
the earth, and so does the fire to your body when you stand before it.
But warm bodies also communicate their heat to substances which touch
them, provided those substances be colder than themselves. Place your
hand upon a cold metal knob, and you will feel that your hand grows
colder as it gives portions of its heat to the knob. This is what
learned men call “conveying” heat.
[To be concluded.]