Every element of _strength_ in a civilized community demands special
notice. The present material progress of nations brings us every day in
contact with the application of power under various conditions, and the
most thoughtless person is to some extent influenced mentally by the
improvements, taking the places of older means and ways of adaptation,
in the arts of life.
We travel by the aid of steam-power, and we think and speak of a
locomotive or a steamboat as we once thought and spoke of a horse or
a man; and no little feeling of self-sufficiency is engendered by the
conclusion that this new source of power has been brought under control
and put to work in our day.
It is also true that we do not always entertain the most correct view of
what we term the new power of locomotive and steamboat; and as it may
aid us in some further steps connected with the subject of my remarks,
a familiar object, such as a steamboat, may be taken as illustrative of
the application of power, and we may thus obtain some simple ideas of
what power truly is, in Nature.
My travelled friend considers a steamboat as a ship propelled by wheels,
the shaft to which they are attached being moved by the machinery.
He follows back to the piston of the engine and finds the motor
there,--satisfied that he has discovered in the transference of
rectilinear to rotatory motion the reason for the progress of the boat.
A more inquisitive friend does not rest here, but assumes that the power
of the steam flowing through the machine sets in action its parts; and
he rests from farther pursuit of the power, where the larger number
of those who give any observation to the application of steam are
found,--gratified with the knowledge accumulated, and the readiness with
which an explanation of the motion of the boat can be traced to the
power of steam as its source.
We must proceed a little farther on our backward course from the point
where the power is applied, and in our analysis consider the steam as
only the vehicle or carrier of the power; and examining the conditions,
we find that water acted on by fire, while contained in a suitable
vessel, after some time takes up certain properties which enable it
to go forward and move the ponderous machinery of the boat. The water
evidently here derives its new character of steam from the fire, and we
have now reached the source of the _movement_ of steam, and traced it
to the fire. In fact, we have found the source of power, in this most
mechanical of all mechanical machines, to be removed from the department
of knowledge which treats of machines!
But we need not pause here, although we must now enter a little way into
chemical, instead of mechanical science. The fire prepares the water to
act as a carrier of power; it must contain power, therefore; and what
is it which we call fire? In placing on the grate coal or wood, and
providing for the contact of a continuous current of air, we intend to
bring about certain chemical actions as consequent on a disposition
which we know coal and wood to possess. When we apply fire, the chemical
actions commence and the usual effects follow. Now, if we for a moment
dismiss the consideration of the means adopted, it becomes apparent to
every one, that, as the fire will continue to increase with successive
additions of fuel, or as it will continue indefinitely with a regular
supply, there must be something else than mere motor action here. We
cannot call it chemical action, and dismiss the thought, and neglect
further inquiry, unless we would place ourselves with those who regard
the movement of the steamboat as being due to the machinery.
Our farther progress in this analysis will soon open a wide field of
knowledge and inquiry; but it is sufficient for our present purpose, if,
by a careful study of the composition and chemical disposition of the
proximate compounds of the coal and the wood fuel, we arrive at the
conclusion that both are the result of forces which, very slight in
themselves at any moment, yet when acting through long periods of time
become laid up in the form of coal and wood. All that effort which the
tree has exhibited during its growth from the germ of the seed to its
state of maturity, when taken as fuel, is pent up in its substance,
ready, when fire is applied, to escape slowly and continuously. In
the case of the coal, after the growth of the plant from which it was
formed, the material underwent changes which enabled it to conserve more
forces, and to exhibit more energy when fire is applied to its mass; and
hence the distinction between wood and coal.
Our analysis thus far has developed the source of the power moving
the steamboat as existing in the gradual action of forces influencing
vegetation, concentrated and locked up in the fuel. For the purpose of
illustrating the subject of this essay, we require no farther progress
in this direction. A moment of thought at this point and we shall cease
to consider steam-power as _new_; for, long before man appeared on this
earth, the vegetation was collecting and condensing those ordinary
natural powers which we find in fuel. In our time, too, the rains and
dews, heat, motion, and gaseous food, are being stored up in a wondrous
manner, to serve as elements of power which may be used and applied now
or hereafter.
In this view, too, we may include the winds, the falling of rain, the
ascent and descent of sap, the condensation of gases,--in short,
the natural powers, exerted before,--as the cause of motion in the
steamboat.
Passing from these considerations not unconnected with the subject, let
us inquire what saltpetre is, and how it is formed.
The term Saltpetre is applied to a variety of bodies, distinguished,
however, by their bases, as potash saltpetre, soda saltpetre, lime
saltpetre, etc., which occur naturally. They are all compounds of nitric
acid and bases, or the gases nitrogen and oxygen united to bases, and
are found in all soils which have not been recently washed by rains, and
which are protected from excessive moisture.
The decomposition of animal and of some vegetable bodies in the soil
causes the production of one constituent of saltpetre, while the earth
and the animal remains supply the other. Evaporation of pure water from
the surface of the earth causes the moisture which rises from below to
bring to the surface the salt dissolved in it; and as this salt is not
volatile, the escape of the moisture leaves it at or near the surface.
Hence, under buildings, especially habitations of men and animals, the
salt accumulates, and in times of scarcity it may be collected. In all
cases of its extraction from the earth several kinds of saltpetre are
obtained, and the usual course is to decompose these by the addition of
salts of potash, so as to form from them potash saltpetre, the kind most
generally consumed.
In this decomposition of animal remains and the formation of saltpetre
the air performs an important part, and the changes it effects are
worthy of our attention.
Let us consider the aërial ocean surrounding our earth and resting upon
it, greatly larger in mass and extent than the more familiar aqueous
ocean below it, and more closely and momentarily affecting our
well-being.
The pure air, consisting of 20.96 volumes of oxygen gas and 79.04
volumes of nitrogen gas, preserves, under all the variations of climate
and height above the surface of the earth, a remarkable constancy of
composition,--the variation of one one-hundredth part never having been
observed. But additions and subtractions are being constantly made,
and the atmosphere, as distinguished from the pure air, is mixed with
exhalations from countless sources on the land and the sea. Wherever man
moves, his fire, his food, the materials of his dwellings, the soil he
disturbs, all add their volatile parts to the atmosphere. Vegetation,
death, and decay pour into it copiously substances foreign to the
composition of pure air. The combustion of one ton of coal adds at least
sixteen tons of impurity to the atmosphere; and when we estimate on
the daily consumption of coal the addition from this source alone, the
amount becomes enormous.
Experiments have been made for the purpose of estimating these
additions, and the results of those most carefully conducted show how
very slightly the combined causes affect the general composition of our
atmosphere; and although the present refined methods of chemists enable
them to detect the presence of an abnormal amount of some substances, no
research has yet been successful in determining how far this varies from
the natural quantity at all times necessarily present in the atmosphere.
It is, however, the comparatively minute portions of nitrogenous matter
in the atmosphere that we are to consider as the source of the nitrous
acids formed there, and of part of that found in the earth. From some
experiments made during the day and night it has been found, that, under
the most favorable circumstances, six millions six hundred and seventy
thousand parts of air afford one part of nitrogenous bodies, if the
whole quantity be abstracted! A portion only of this quantity can be
withdrawn in natural operations, such as the falling of rain and the
deposition of dew,--the larger part always remaining behind.
When the oxygen of our atmosphere is exposed, while in its usual
hygrometric state, to the influence of bodies attracting a portion of
it, such as decomposing substances, or when it forms the medium of
electrical discharges, it suddenly assumes new powers, acquires a
greatly increased activity, affects our organs of smell, dissolves
in fluids, and has been mistaken for a new substance, and even named
"ozone." Among the new characters thus conferred on it is the power of
uniting with or burning many substances. This ozonized oxygen, when
brought into mixture with many nitrogenized bodies, forms with them
nitrous acids, completely destroying their former condition and
composition; hence, in the atmosphere, this part of the oxygen becomes
a purifier of the whole mass, from which it removes putrescent
exhalations, miasmatic vapors, and the effluvia from every source of sea
or land. Very curious are the effects of this active oxygen, which is
ever present in some portion of the atmosphere. Moved by the wind, mixed
with the impure upward currents rising from cities, it seizes on
and changes rapidly all foulness, and if the currents are not too
voluminous, the impure air becomes changed to pure. As ozonized oxygen
can be easily detected, we may pass from the city, where (overpowered
by the exhalations) it does not exist, and find it in the air of the
vicinity; and moving away several miles, ascertain that a normal amount
there prevails, and that step by step, on our return to abodes of a
dense population, the quantity diminishes and finally all disappears.
We are now prepared to answer the second part of the question which was
suggested, and to find that nitrous acids formed in the atmosphere
by direct oxidation of nitrogenous matter may unite with the ammonia
present to produce one kind of saltpetre; and when the rains or the dews
carry this to the earth, the salts of lime, potash, and soda there found
will decompose this ammoniacal saltpetre, and set the ammonia free, to
act over again its part. So in regard to decomposing organic matters in
the soil: ozonized oxygen changes them in the same way. The earth
and calcareous rocks of caves, penetrated by the air, slowly produce
saltpetre, and before the theory of the action was understood,
artificial imitation of natural conditions enabled us to manufacture
saltpetre. Animal remains, stratified with porous earth or the sweepings
of cities, and disposed in long heaps or walls, protected from rain, but
exposed to the prevailing winds, soon form nitrous salts, and a large
space covered with these deposits carefully tended forms a saltpetre
plantation. France, Prussia, Sweden, Switzerland, and other countries,
have been supplied with saltpetre from similar artificial arrangements.
But the atmosphere is washed most thoroughly by the rains falling in and
near tropical countries, and the changes there are most rapid, so that
the production of saltpetre, favored by moisture and hot winds, attains
its highest limit in parts of India and the bordering countries.
During the prevalence of dry winds, the earth in many districts of India
becomes frosted over with nitrous efflorescences, and the great quantity
shipped from the commercial ports, and that consumed in China, is thus a
natural production of that region. The increased amount due to tropical
influences will be seen in the instances here given of the produce from
the rich earths of different countries:--
_Natural_.
France, Church of Mousseau, 5-3/8 per cent.
" Cavern of Fouquières, 3-1/2 "
U. States, Tennessee, dirt of caves, 0.86 "
Ceylon, Cave of Memoora, 3-1/10 "
Upper Bengal, Tirhoot, earth simply, 1-6/10 "
Patree in Guzerat, best sweepings, 8-7/10 "
In each case the salt is mixed saltpetres.
_Artificial_.
France, 100 lbs. earth from
plantations afford 8 to 9 oz.
Hungary and Sweden, from
the same, 1/2 to 2-3/10 per cent.
It may be calculated that the flesh of animals, free from bone,
carefully decomposed, will afford ninety-five pounds of saltpetre for
one thousand pounds thus consumed.
In the manufacture of saltpetre, the earths, whether naturally or
artificially impregnated, are mixed with the ashes from burnt wood, or
salts of potash, so that this base may take the place of all others, and
produce long prisms of potash saltpetre.
In this country there are numerous caves of great extent in Kentucky,
Tennessee, and Missouri, from which saltpetre has been manufactured.
Under the most favorable conditions of abundance of labor, obtainable
at a low price, potash saltpetre can be made at a cost about one-fourth
greater than the average price of India saltpetre, and those sources of
supply are the best natural deposits known on this side of the Rocky
Mountains. Where there is an insufficient supply of manure in a country,
resort to the artificial production of saltpetre is simply a robbery
committed on the resources of the agriculturists, and it is only during
the pressure of a great struggle like that of the wars of Napoleon, that
the conversion into saltpetre of materials which can become food for the
community would be permitted.
Hitherto, in peaceful times, our supply of saltpetre has come from India
through commercial channels; but twice within a few years this course of
trade has been interrupted by the British Government, and the price of a
necessary article has been greatly enhanced,--leading reflecting minds
to the inquiry after other sources whence to draw the quantity required
for an increasing consumption. On the boundary between Peru and Chili,
in South Peru, about forty miles from the ports of Conception and
Iquique, is a depression in the general surface of a saline desert,
where a bed of soda saltpetre, about two and a half feet thick and
one hundred and fifty miles long, exists. The salt is massive, and,
occurring in a rainless climate, it is dry, and contains about sixty per
cent. of pure soda saltpetre. In Brazil, on the San Francisco, the same
salt is found extending sixty or seventy miles,--and again near the town
of Pilao Arcado, the beds being about two hundred and forty miles from
Bahia, but at present inaccessible for want of roads. The Peruvian
native saltpetre is rudely refined in the desert, and then transported
on the backs of mules to the shipping-port. As found in commerce, it is
less impure than India saltpetre; and it might be usefully substituted
for the latter in the manufacture of gunpowder, were it less
deliquescent in damp atmospheres. For chemical purposes it now replaces
India saltpetre, but the larger consumption is perhaps as a fertilizer
of land, in the cool and humid climate of England, the low price it
bears in the market permitting this consumption.
We have found that the various saltpetres of natural production, or
those obtained in artificial arrangements, are converted by the use of
potash salts into potash saltpetre, and among the products so changed is
natural soda saltpetre. Now to us in this country, so near the sources
of abundant supply of soda saltpetre, this substitution becomes a matter
of great interest. We possess and can produce the alkaline salt of
potash in almost unlimited quantity, and, excepting for some special
purposes, it is consumed for its alkaline energy alone. When soda
saltpetre in proper proportion is dissolved and thus mixed with potash
salt, an exchange of bases takes place, and no loss of alkaline energy
follows. The soda in a quite pure state is eliminated from the soda
saltpetre, and will serve for the manufactures of glass and soap; while
the potash, taking the oxygen compound of the soda saltpetre, produces,
as a final result, a pure and beautiful prismatic saltpetre, most
economically and abundantly.
Instead of working on a hundred pounds of earth to obtain at most eight
or nine pounds of saltpetre, a hundred pounds of soda saltpetre will
afford more than one hundred and nine pounds of potash saltpetre, when
skilfully treated. Here, then, we have, by simple chemical treatment
of an imported, but very cheap salt, a result constituting a source of
abundant supply of potash saltpetre, _without the loss of the agent_
concerned in the transformation.
We have traced slightly in outline the formation of saltpetre to the
action of ozonized oxygen on nitrogen compounds, in the atmosphere, or
in the earth,--the conditions being the same in both cases. If we pursue
the study of this action of ozonized oxygen farther, we shall not
restrict its combining disposition to these compounds, but prove that it
has the power of uniting directly with the nitrogen naturally forming
part of the pure air. While nitrogenized bodies are present, however,
in the atmosphere, or in the humid artificial heaps of saltpetre
plantations, the action of ozonized oxygen is on these, and the nitrous
compounds formed unite with the bases lime, soda, and potash, also
present, to form saltpetre.
Under all the conditions necessary, we see the permanent gases, oxygen
and nitrogen, leaving the atmosphere and changing from their gaseous to
a solid dry state, when they become chemically combined with potash, and
there are 53-46/100 parts of the gaseous matter and 46-54/100 parts of
the potash in 100 parts of the saltpetre by weight.
Having now found what saltpetre is and how it is formed, let us advance
to the consideration of it as a source of power.
Through the exertion of chemical attraction the gaseous elements of the
atmosphere have become solid in the saltpetre; and as we know the weight
of this part in a cubic inch of saltpetre, the volume of the gases
combined is easily ascertained to be about eight hundred times that of
the saltpetre. Hence, as every cubic inch of condensation represents
an atmosphere as large as the cubic inch of saltpetre formed, we may
roughly estimate that the condensing force arising from chemical
attraction in this case is 800 times 15 lbs., or 12,000 lbs.!
Strictly speaking, only about four-tenths of a cubic inch of potash
holds this enormous power in connection with it so as to form a cubic
inch of saltpetre, which we may handle and bruise, may melt and cool,
dissolve and crystallize, without explosion or change. It contains
conserved a force which represents the aggregate result of innumerable
minute actions, taking place among portions of matter which escape
our senses from their minuteness and excite our wonder by their
transformation. Closely similar are these actions to the agencies in
vegetation which build up the wood of the tree or the material of
the coal destined to serve for the production of fire in all the
applications of steam which we have briefly noticed in illustration.
In availing ourselves of the concentrated power accumulated in
saltpetre, we resort to bodies which easily kindle when fire is applied,
such as sulphur and finely powdered charcoal: these substances are
most intimately mixed with the saltpetre in a powdered state, and the
dampened mass subjected to great pressure is afterwards broken into
grains of varied size, constituting gunpowder.
The substances thus added to the saltpetre have both the disposition and
the power of burning with and decomposing the nitrous element of the
saltpetre, and in so doing they do not simply open the way for the
energetic action of the gases escaping, but, owing to the high
temperature produced, a new force is added.
If the gases escaped from combination simply, they would exert for every
cubic inch of saltpetre, as we have here considered it, the direct power
of 12,000 lbs.; but under the new conditions, the volume of escaping gas
has a temperature above 2,000° Fahrenheit, and consequently its force
in overcoming resistance is more than four times as great, or at least
48,000 lbs.
Such, then, is the power which can be obtained from a cubic inch of
saltpetre, when it is so compounded as to form some of the kinds of
gunpowder; and the fact of greatest importance in this connection is the
control we have over the amount of the force exerted and the time in
which the energy can be expended, by variations in the proportions of
the eliminating agents employed.
We have used the well-known term Gunpowder to express the compound by
which we easily obtain the power latent in saltpetre; and the use of the
term suggests the employment of guns, which is secondary to the main
point we are illustrating. As the enormous consumption of power takes
place during peaceful times, so the consumption of saltpetre during a
state of war is much lessened, because the prosecution of public and
private works is then nearly suspended.
The value and importance of saltpetre as a source of power is seen in
the adaptation of its explosive force to special purposes. It performs
that work well which we cannot carry on so perfectly by means of any
other agent, and the great mining and engineering works of a country are
dependent on this source for their success, and for overcoming obstacles
where other forces fail. With positive certainty the engineer can remove
a portion of a cliff or rock without breaking it into many parts, and
can displace masses to convenient distances, under all the varying
demands which arise in the process of mining, tunnelling, or cutting
into the earth.
In all these cases of application we see that the powder contains within
itself both the material for producing force and the means by which that
force is applied, no other motor being necessary in its application.
Modern warfare has become in its simplest expression the intelligent
application of force, and that side will successfully overcome or resist
the other which can in the shortest time so direct the greater force.
In artillery as well as infantry practice, the control over the time
necessary in the decomposition of the powder has been obtained through
the refinements already made in the manufacture, and the best results
of the latest trials confirm in full the conclusion that saltpetre is a
source of great and easily controlled power, which can act through short
or extended space.
Under the view here presented, it is evident that saltpetre is
indispensable to progress in the arts of civilization and peace, as well
as in military operations, and that no nation can advance in material
interests, or even maintain strict independence, without possessing
within its boundaries either saltpetre or the sources from which it
can be drawn at all times. In its use for protecting the property of
a nation from the attacks of an enemy, and as the means of insuring
respect, we may consider saltpetre as an element of strength in a State,
and as such deserving a high place in the consideration of those who
direct the counsels or form the policy of a country.
Has the subject of having an exhaustless supply of this important
product or the means of producing it been duly considered?
* * * * *