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requiring a force greater than the earth to given portion of steel into a magnet of a force excite it; and when once it has been forced proportioned to its capacity of retaining its from one extremity of the steel to the other, magnetic fluid in the new position in which it it is not easy for it to return; and thus a bar is placed, without letting it return. Now this of steel is converted into a permanent magnet. power is different in different kinds of steel,

6thly, A great heat, by expanding the sub but limited in all kinds whatever. stance of this steel, and increasing the dis

B. FRANKLIN. tance between its particles, affords a passage to the electric fluid, which is thus again restored to its proper equilibrium; the bar ap To Messrs. Dubourg and d’Alibard.* pearing no longer to possess magnetic virtue. Concerning the Mode of rendering Meat tender 7thly, A bar of steel which is not magnetic,

by Electricity. being placed in the same position, relatively to the pole of the earth, which the magnetic the mode of rendering meat tender by electri

My answer to your questions concerning needle assumes, and in this position being city, can only be founded upon conjecture; heated and suddenly cooled, becomes a perma- for i have not experiments enough to warrant nent magn

The reason is, that while the the facts. All that I can say at present is, bar yas hot, the magnetic fluid which it na- that I think electricity might be employed for turally contained was easily forced from one this purpose, and I shall state what follows as extremity to the other by the magnetic virtue the observations or reasons, which make me of the earth; and that the hardness and condensation, produced by the sudden cooling of presume so.

It has been observed, that lightning, by the bar, retained it in this state without per- rarefying and reducing into vapour the moistmitting it to resume its original situation. 8thly, The violent vibrations of the parti- stance, has forcibly separated its fibres, and

ure contained in solid wood, in an oak, for incles of a steel bar, when forcibly struck in the broken it into small splinters; that by penesame position, separate the particles in such trating intimately the hardest metals

, as iron, a manner during their vibration, that they it has separated the parts in an instant, so as permit a portion of the magnetic fluid to pass, to convert a perfect solid into a state of fluidinfluenced by the natural magnetism of the earth; and it is afterwards so forcibly retain- ity: it is not then improbable, that the same

subtle matter, passing through the bodies of ed by the re-approach of the particles when the vibration ceases, that the bar becomes a force to produce an effect nearly similar.

animals with rapidity, should possess sufficient permanent magnet.

The flesh of animals, fresh killed in the 9thly, An electric shock passing through a usual manner, is firm, hard, and not in a very necdle in a like position, and dilating it for eatable state, because the particles adhere too an instant, renders it, for the same reason, a

forcibly to each other. At a certain period, permanent magnet; that is, not by imparting the cohesion is weakened and in its progress magnetism to it, but by allowing its proper towards putrefaction, which tends to produce magnetic fluid to put itself in motion.

a total separation, the flesh becomes what we idthly, Thus, there is not in reality more call tender, or is in that state most proper to magnetism in a given piece of steel after it is be used as our food. become magnetic, than existed in it before.

It has frequently been remarked, that aniThe natural quantity is only displaced or remals killed by lightning putrefy immediately. pelled. Hence it followe, that a strong ap: This cannot be invariably the case, since a paratus of magnets may charge millions of quantity of lightning sufficient to kill,

may bars of steel, without communicating to them not be sufficient to tear and divide the fibres any part of its proper magnetism; only put- and particles of flesh, and reduce them to that ting in motion the magnetism which already tender state, which is the prelude to putrefacexisted in these bars.

tion. Hence it is, that some animals killed I am chiefly indebted to that excellent phi- in this manner will keep longer than others. losopher of Petersburgh, Mr. Æpinus, for this But the putrefaction sometimes proceeds with hypothesis, which appears to me equally in

surprising celerity. A respectable person asgenious and solid. I say, chiefly, because, as sured me, that he once knew a remarkable it is many years since I read his book, which instance of this : a whole flock of sheep in I have left in America, it may happen, that I

Scotland, being closely assembled under a tree, may have added to or altered it in some respect; and if I have misrepresented any thing, being rather late in the evening, the proprie

were killed by a flash of lightning; and it the error ought to be charged to my account, tor, desirous of saving something, sent perIf this hypothesis appears admissible, it will

sons early the next morning to flay them: but serve as an answer to the greater part of your the putrefaction was such, and the stench so questions. I have only one remark to add, which is, that however great the force is of

* This letter has no date, but the one to which it is magnetism employed, you can only convert a an answer is dated May 1, 1773.

abominable, that they had not the courage to

To M. Dubourg, execute their orders, and the bodies were accordingly buried in their skins. It is not un- In Answer to some Queries concerning the reasonable to presume, that between the

choice of Glass for the Leyden experiment.

period of their death and that of their putrefac

LONDON, June 1, 1773. tion, a time intervened in which the flesh SIR,—I wish, with you, that some chemist might be only tender, and only sufficiently so (who should, if possible, be at the same time to be served at table. Add to this, that per- an electrician) would, in pursuance of the ex. sons, who have eaten of fowls killed by our cellent hints contained in your letter, underfeeble imitation of lightning (electricity) and take to work upon glass with the view you dressed immediately, have asserted, that the have recommended. By means of a perfect flesh was remarkably tender.

knowledge of this substance, with respect to The little utility of this practice has per- its electrical qualities, we might proceed with haps prevented its being much adopted. For more certainty, as well in making our own though it sometimes happens, that a company experiments, as in repeating those which unexpectedly arriving at a country-house, or have been made by others in different counan unusual conflux of travellers to an inn, tries, which I believe have frequently been may render it necessary, to kill a number of attended with different success on account of animals for immediate use; yet as travellers differences in the glass employed, thence ochave commonly a good appetite, little atten- casioning frequent misunderstandingsand contion has been paid to the trifling inconveni- trariety of opinions. ence of having their meat a little tough. As There is another circumstances h to be this kind of death is nevertheless more sud- desired with respect to glass, and that is, that den, and consequently less severe, than any it should not be subject to break when highly other, if this should operate as a motive with charged in the Leyden experiment. I have compassionate persons to employ it for ani- known eight jars broken out of twenty, and mals sacrificed for their use, they may con- at another time, twelve out of thirty-five. A duct the process thus:

similar loss would greatly discourage elecHaving prepared a battery of six large tricians desirous of accumulating a great glass jars (each from 20 to 24 pints) as for power for certain experiments.-We have the Leyden experiment, and having establish- never been able hitherto to account for the ed a communication, as usual, from the inte cause of such misfortunes. The first idea rior surface of each with the prime conduct- which occurs is, that the positive electricity, or, and having given them a full charge being accumulated on one side of the glass, (which with a good machine may be executed rushes violently through it, in order to supin a few minutes, and may be estimated by ply the deficiency on the other side, and to rean electrometer) a chain which communicates store the equilibrium. This however, I cannot with the exterior of the jars must be wrapped conceive to be the true reason, when I conround the thighs of the fowl; after which sider, that a great number of jars being the operator, holding it by the wings, turned united, so as to be charged and discharged at back and made to touch behind, must raise it the same time, the breaking of a single jar 80 high that the head may receive the first will discharge the whole ; for, if the accident shock from the prime conductor. The ani- proceeded from the weakness of the glass, it mal dies instantly. Let the head be imme- is not probable, that eight of them should be diately cut off to make it bleed, when it may precisely of the same degree of weakness, as be plucked and dressed immediately. This to break every one at the same instant, it bequantity of electricity is supposed sufficient ing more likely that the weakest should for a turkey of ten pounds' weight, and per- break first, and, by breaking, secure the rest; haps for a lamb. Experience alone will in- and again, when it is necessary to produce a form us of the requisite proportions for ani- certain effect, by means of the whole charge mals of different forms and ages. Probably passing through a determined circle (as, for not less will be required to render a small instance, to melt a small wire) if the charge, bird, which is very old, tender, than for a instead of passing in this circle, rushed through larger one, which is young. It is easy to fur- the sides of the jars, the intended effect nish the requisite quantity of electricity, by would not be produced; which, however, is employing a greater or less number of jars. contrary to fact. For these reasons, I susAs six jars, however, discharged at once, are pect, that there is, in the substance of the capable of giving a very violent shock, the glass, either some little globules of air, or operator must be very circumspect, lest he some portions of unvitrified sand or salt, into should happen to make the experiment on which a quantity of the electric fluid may

be his own flesh, instead of that of the fowl. forced during the charge, and there retained

B. FRANKLIN. till the general discharge: and that the force

being suddenly withdrawn, the elasticity of supported by them; for in the vacancies there the Auid acts upon the glass in which it is is nothing they can rest on. enclosed, not being able to escape hastily Air and water mutually attract each other. without breaking the glass. I offer this only Hence water will dissolve in air, as salt in as a conjecture, which I leave to others to water. examine.

The specific gravity of matter is not alterThe globe which I had that could not be ed by dividing the matter, though the superexcited, though it was from the same glass- fices be increased. Sixteen leaden bullets, house which furnished the other excellent of an ounce each, weigh as much in water as globes in my possession, was not of the same one of a pound, whose superfices is less. frit. The glass which was usually manu Therefore the supporting of salt in water factured there, was rather of the green kind, is not owing to its superfices being increased. and chiefly intended for drinking-glasses and A lump of salt, though laid at rest at the bottles; but the proprietors being desirous of bottom of a vessel of water, will dissolve attempting a trial of white glass, the globe therein, and its parts move every way, till in question was of this frit. The glass not equally diffused in the water, therefore there being of a perfect white, the proprietors is a mutual attraction between water and salt. were dissatisfied with it, and abandoned their Every particle of water assumes as many of project. I suspected that too great a quantity salt as can adhere to it; when more is adof salt was admitted into the composition; but ded, it precipitates, and will not remain susI am no judge of these matters

pended B. FRANKLIN. Water, in the same manner, will dissolve

in air, every particle of air assuming one or more particles of water. When too much is ad

ded, it precipitates in rain. Miss Stephenson

But there not being the same contiguity Concerning the Leyden Bottle.

between the particles of air as of water, the

solution of water in air is not carried on LONDON, March 22, 1762.

without a motion of the air, so as to cause a I MUST retract the charge of idleness in fresh accession of dry particles. your studies, when I find you have gone

Part of a fluid, having more of what it disthrough the doubly difficult task of reading so big a book, on an abstruse subject, and in a have less. Thus very salt water, coming in

solves, will communicate to other parts that foreign language. In answer to your question concerning the till all is equal, and the sooner if there is a little

contact with fresh, communicates its saltness Leyden phial.- The hand that holds the bottle motion of the water. receives and conducts away the electric fluid that is driven out of the outside by the repul- A stroke of a horse's hoof on the ground, in

Even earth will dissolve, or mix with air. sive power of that which is forced into the in

a hot dusty road, will raise a cloud of dust, side of the bottle. As long as that power re- that shall, if there be a light breeze, expand mains in the same situation, it must prevent the return of what it had expelled; though every way, till perhaps

near as big as a comthe hand would readily supply the quantity if communicated to the particles of dust by the

mon house. It is not by mechanical motion it could be received. B. FRANKLIN.

hoof, that they fly so far, not by the wind, that they spread so wide; but the air near

the ground, more heated by the hot dust struck Physical and Meteorological Observations, into it, is rarefied and rises, and in rising

mixes with the cooler air, and communicates Conjectures, and Suppositions. Read at

of its dust to it, and it is at length so diffused the Royal Society, June 3, 1756.

as to become invisible. Quantities of dust The particles of air are kept at a distance are thus carried up in dry seasons: showers from each other by their mutual repulsion. wash it from the air, and bring it down again.

Every three particles, mutually and equal- For water attracting it stronger, it quits the ly repelling each other, must form an equilate air, and adheres to the water, ral triangle.

Air, suffering continual changes in the deAll the particles of air gravitate towards grees of its heat, from various causes and cirthe earth, which gravitation compresses them, cumstances, and consequently, changes in its and shortens the sides of the triangles, specific gravity, must therefore be in contiotherwise their mutual repellency would nual motion. force them to greater distances from each A small quantity of fire mixed with water other.

(or degree of heat therein) so weakens the Whatever particles of other matter (not en- cohesion of its particles, that those on the surdued with that repellency) are supported in face easily quit it, and adhere to the particles air, must adhere to the particles of air, and be of air. VOL. II. ...2 T

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Air moderately heated will support a great

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0 O 0 O if a would descend to Hence when we breathe in warm air,

E, it must pass between though the same quantity of moisture may be B and c; when it comes between B and C, taken up from the lungs, as when we breathe it will be nearer to them than before, and in cold air, yet that moisture is not so visible. must either have pushed them nearer to r

Water being extremely heated, i. e. to the and G, contrary to their mutual repellency, degree of boiling, its particles in quitting it so or pass through by a force exceeding its rerepel each other, as to take up vastly more pellency with them. It then approaches D, space than before, and by that repellency sup- and, to move it out of the way, must act on port themselves, expelling the air from the it with a force sufficient to overcome its respace they occupy. That degree of heat be- pellency with the two next lower particles, ing lessened, they again mutually attract, by which it is kept in its present situation. and having no air particles mixed to adhere Every particle of air, therefore, will bear to, by which they might be supported and any load inferior to the force of these repulkept at a distance, they instantly fall, coalesce, sions. and become water again.

Hence the support of fogs, mists, clouds. The water commonly diffused in our at Very warm air, clear, though supporting a mosphere never receives such a degree of heat very great quantity of moisture, will grow from the sun, or other cause, as water has turbid and cloudy on the mixture of colder when boiling; it is not, therefore, supported air, as foggy turbid air will grow clear by by such heat, but by adhering to air. warming

Water being dissolved in, and adhering to Thus the sun shining on a morning fog, air, that air will not readily take up oil, be dissipates it; clouds are seen to waste in a cause of the mutual repellency between wa- sun-shiny day. ter and oil.

But cold condenses and renders visible the Hence cold oils evaporate but slowly, the vapour : a tankard or decanter filled with air having generally a quantity of dissolved cold water will condense the moisture of water.

warm clear air on its outside, where it beOil being heated extremely, the air that comes visible as dew, coalesces into drops, approaches its surface will be also heated ex- descends in little streams. tremely; the water then quitting it, it will The sun heats the air of our atmosphere attract and carry off the oil, which can now most near the surface of the earth; for there, adhere to it. Hence the quick evaporation besides the direct rays, there are many reof oil heated to a great degree.

flections. Moreover, the earth itself being Oil being dissolved in air, the particles to heated, communicates of its heat to the which it adheres will not take up water. neighbouring air.

Hence the suffocating nature of air impreg. The higher regions, having only the direct nated with burnt grease, as from snuffs of rays of the sun passing through them, are candles and the like. A certain quantity of comparatively very cold. Hence the cold moisture should be every moment discharged air on the tops of mountains, and snow on and taken away from the lungs; air that has some of them all the year, even in the torrid been frequently breathed, is already over- zone. Hence hail in summer. loaded, and, for that reason, can take no more, If the atmosphere were, all of it (both so will not answer the end. Greasy air re- above and below) always of the same temper fuses to touch it. In both cases suffocation as to cold or heat, then the upper air would for want of the discharge.

always be rarer than the lower, because the Air will attract and support many other pressure on it is less; consequently lighter, substances.

and therefore would keep its place. A particle of air loaded with adhering wa But the upper air may be more condensed ter, or any other matter, is heavier than be- by cold, than the lower air by pressure; the fore, and would descend.

lower more expanded by heat, than the upThe atmosphere supposed at rest, a loaded per for want of pressure. In such case the descending particle must act with a force on upper air will become the heavier, the lower the particles it passes between, or meets the lighter. with, sufficient to overcome, in some degree, The lower region of air being heated and their mutual repellency, and push them nearer expanded heaves up, and supports for some time to each other.

the colder heavier air above, and will conti

nue to support it while the equilibrium is kept. fied by the sun, rises. Its place is supplied Thus water is supported in an inverted open by air from northern and southern latitudes, glass, while the equilibrium is maintained by which coming from parts wherein the earth the equal pressure upwards of the air below; and air had less motion, and not suddenly acbut the equilibrium by any means breaking, quiring the quicker motion of the equatorial the water descends on the heavier side, and earth, appearsan east wind blowing westward; the air rises into its place.

the earth moving from west to east, and slip-' The lifted heavy cold air over a heated, ping under the air.* country, becoming by any means unequally Thus, when we ride in a calm, it seems a supported, or unequal in its weight, the hea- wind against us: if we ride with the wind, viest part descends first, and the rest follows and faster, even that will seem a small wind impetuously. Hence gusts after heats, and against us. hurricanes in hot climates. Hence the air of The air rarefied between the tropics, and gusts and hurricanes is cold, though in hot rising, must flow in the higher region north climates and seasons; it coming from above. and south. Before it rose, it had acquired

The cold air descending from above, as it the greatest motion the earth's rotation could penetrates our warm region full of watery par- give it. It retains some degree of this moticles, condenses them, renders them visible, tion, and descending in higher latitudes, forms a cloud thick and dark, overcasting where the earth's motion is less, will appear sometimes, at once, large and extensive ; a' westerly wind, yet tending towards the sometimes, when seen at a distance, small at equatorial parts, to supply the vacancy occafirst, gradually increasing; the cold edge, or sioned by the air of the lower regions flowing surface of the cloud, condensing the vapours

thitherwards. next it, which form smaller clouds that join Hence our general cold winds are about it, increase its bulk, it descends with the wind north west, our summer cold gusts the same. and its acquired weight, draws nearer the

The air in sultry weather, though not earth, grows denset with continual additions cloudy, has a kind of haziness in it, which of water, and discharges heavy showers. makes objects at a distance appear dull and

Small black clouds thus appearing in a clear indistinct. This haziness is occasioned by sky, in hot climates, portend storms, and warn the great quantity of moisture equally diffused seamen to hand their sails.

in that air. When, by the cold wind blowing The earth, turning on its axis in about down among it, it is condensed into clouds, twenty-four hours, the equatorial parts must and falls in rain, the air becomes purer and move about fifteen miles in each minute; clearer. Hence, after gusts, distant objects in northern and southern latitudes this mo- appear distinct, their figures sharply termition is gradually less to the poles, and there nated. nothing

Extreme cold winds congeal the surface of If there was a general calm over the face the earth, by carrying off its fire. Warm of the globe, it must be by the air's moving winds afterwards blowing over that frozen in every part as fast as the earth or sea it surface will be chilled by it. Could that

frozen surface be turned under, and warmer He that sails, or rides, has insensibly the turned up from beneath it, those warm winds same degree of motion as the ship or coach would not be chilled so much. with which he is connected. If the ship

The surface of the earth is also sometimes strikes the shore, or the coach stops suddenly, much heated by the sun : and such heated surthe motion continuing in the man, he is thrown face not being changed heats the air that forward. If a man were to jump from the moves over it. land into a swift sailing ship, he would be Seas, lakes, and great bodies of water, agithrown backward (or towards the stern) not tated by the winds, continually change surhaving at first the motion of the ship. faces; the cold surface in winter is turned

He that travels by sea or land, towards the under by the rolling of the waves, and a equinoctial, gradually acquires motion ; from warmer turned up; in summer, the warm is it, loses.

turned under, and colder turned up. Hence But if a man were taken up from latitude the more equal temper of sea-water, and the 40 (where suppose the earth's surface to move air over it. Hence, in winter, winds from the twelve miles per minute) and immediately sea seem warm, winds from the land cold. set down at the equinoctial, without chang. In summer the contrary. ing the motion he had, his heels would be Therefore the lakes north-west of us,t as struck up, he would fall westward. If taken they are not so much frozen, nor so apt to up from the equinoctial, and set down in lati

* See a paper on this subject, by the late ingenious tude 40, he would fall eastward.

Mr. Hadley, in the Philosophical Transactions, where. The air under the equator, and between in this hypothesis for explaining the trade-winds first:

appeared. the tropics, being constantly heated and rare

f In Pennsylvania.

covers.

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