Читать книгу: «The Atlantic Monthly, Volume 09, No. 55, May, 1862», страница 8
THE TITMOUSE
You shall not be over-bold
When you deal with arctic cold,
As late I found my lukewarm blood
Chilled wading in the snow-choked wood.
How should I fight? my foeman fine
Has million arms to one of mine.
East, west, for aid I looked in vain;
East, west, north, south, are his domain.
Miles off, three dangerous miles, is home;
Must borrow his winds who there would come.
Up and away for life! be fleet!
The frost-king ties my fumbling feet,
Sings in my ears, my hands are stones,
Curdles the blood to the marble bones,
Tugs at the heartstrings, numbs the sense,
Hems in the life with narrowing fence.
Well, in this broad bed lie and sleep,
The punctual stars will vigil keep,
Embalmed by purifying cold,
The winds shall sing their dead-march old,
The snow is no ignoble shroud,
The moon thy mourner, and the cloud.
Softly,—but this way fate was pointing,
'Twas coming fast to such anointing,
When piped a tiny voice hard by,
Gay and polite, a cheerful cry,
"Chic-chic-a-dee-dee!" saucy note,
Out of sound heart and merry throat,
As if it said, "Good day, good Sir!
Fine afternoon, old passenger!
Happy to meet you in these places,
Where January brings few men's faces."
This poet, though he live apart,
Moved by a hospitable heart,
Sped, when I passed his sylvan fort,
To do the honors of his court,
As fits a feathered lord of land,
Flew near, with soft wing grazed my hand,
Hopped on the bough, then, darting low,
Prints his small impress on the snow,
Shows feats of his gymnastic play,
Head downward, clinging to the spray.
Here was this atom in full breath
Hurling defiance at vast death,
This scrap of valor just for play
Fronts the north-wind in waistcoat gray,
As if to shame my weak behavior.
I greeted loud my little saviour:
"Thou pet! what dost here? and what for?
In these woods, thy small Labrador,
At this pinch, wee San Salvador!
What fire burns in that little chest,
So frolic, stout, and self-possest?
Didst steal the glow that lights the West?
Henceforth I wear no stripe but thine:
Ashes and black all hues outshine.
Why are not diamonds black and gray,
To ape thy dare-devil array?
And I affirm the spacious North
Exists to draw thy virtue forth.
I think no virtue goes with size:
The reason of all cowardice
Is, that men are overgrown,
And, to be valiant, must come down
To the titmouse dimension."
'Tis good-will makes intelligence,
And I began to catch the sense
Of my bird's song: "Live out of doors,
In the great woods, and prairie floors.
I dine in the sun; when he sinks in the sea,
I, too, have a hole in a hollow tree.
And I like less when summer beats
With stifling beams on these retreats
Than noontide twilights which snow makes
With tempest of the blinding flakes:
For well the soul, if stout within,
Can arm impregnably the skin;
And polar frost my frame defied,
Made of the air that blows outside."
With glad remembrance of my debt,
I homeward turn. Farewell, my pet!
When here again thy pilgrim comes,
He shall bring store of seeds and crumbs.
Henceforth I prize thy wiry chant
O'er all that mass and minster vaunt:
For men mishear thy call in spring,
As 'twould accost some frivolous wing,
Crying out of the hazel copse, "Phe—be!"
And in winter, "Chic-a-dee-dee!"
I think old Caesar must have heard
In Northern Gaul my dauntless bird,
And, echoed in some frosty wold,
Borrowed thy battle-numbers bold.
And I shall write our annals new,
And thank thee for a better clew:
I, who dreamed not, when I came here,
To find the antidote of fear,
Now hear thee say in Roman key,
"Paean! Ve-ni, Vi-di, Vi-ci."
* * * * *
SALTPETRE AS A SOURCE OF POWER
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?
