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mocritus for the introduction of a vacuum, | bound down, or otherwise confined, and yet strive (namely, that the same bodies could not other wise comprehend and fill greater and less spaces,) is false. For there is clearly a folding of matter, by which it wraps and unwraps itself in space within certain limits, without the intervention of a vacuum. Nor is there two thousand times more of vacuum in air than in gold, as there should be on this hypothesis; a fact demonstrated by the very powerful energies of fluids, (which would otherwise float like fine dust in vacuo,) and many other proofs. The other motions direct and are directed by each other according to their strength, quantity, excitement, emission, or the assistance or impediments they meet with.

with all his power to get up, the struggle is not the less, although ineffectual. The real state of the case (namely, whether the yielding motion be, as it were, annihilated by the predominance, or there be rather a continued although an invisible effort) will perhaps appear in the concurrence of motions, although it escape our notice in their conflict. For instance, let an experiment be made with muskets; whether a musket ball, at its utmost range in a straight line, or, as it is commonly called, point blank, strike with less force when projected upwards, where the motion of the blow is simple, than when projected downwards, where the motion of gravity concurs with the blow.

the stronger will be the motion; the motion of connexion, for instance, which relates to the intercourse of the parts of the universe, is more powerful than that of gravity, which relates to the intercourse of dense bodies only. Again, the desire of a private good does not, in general, prevail against that of a public one, except where the quantities are small. Would that such were the case in civil matters!

For instance, some armed magnets hold and The rules of such instances of predominance support iron of sixty times their own weight; so as occur, should be collected: such as the followfar does the motion of lesser congregation predo-ing; the more general the desired advantage is, minate over that of the greater; but if the weight be increased, it yields. A lever of a certain strength will raise a given weight, and so far the motion of liberty predominates over that of the greater congregation, but if the weight be greater, the former motion yields. A piece of leather stretched to a certain point does not break, and so far the motion of continuity predominates over that of tension, but if the tension be greater, the leather breaks, and the motion of continuity yields. A certain quantity of water flows through a chink, and so far the motion of greater congregation predominates over that of continuity, but if the chink be smaller, it yields. If a musket be charged with ball and powdered sulphur alone, and fire be applied, the ball is not discharged, in which case the motion of greater congregation overcomes that of matter, but when gunpowder is used, the motion of matter in the sulphur predominates, being assisted by that motion and the motion of avoidance in the nitre; and so of the rest. For wrestling instances (which show the predominance of powers, and in what manner and proportion they predominate and yield) must be searched for with active and industrious diligence.

The methods and nature of this yielding must also be diligently examined; as, for instance, whether the motions completely cease or exert themselves, but are constrained. For, in the bodies with which we are acquainted, there is no real, but an apparent rest, either in the whole or in parts. This apparent rest is occasioned either by equilibrium or the absolute predominance of motions. By equilibrium, as in the scales of the balance, which rest if the weights be equal. By predominance, as in perforated jars, in which the water rests, and is prevented from falling by the predominance of the motion of connection. It is, however. to be observed (as we have said betore) how far the yielding motions exert themselves. For, if a man be held stretched out on the ground against his will, with arms and legs

49. In the twenty-fifth rank of prerogative instances, we will place suggesting instances; such as suggest or point out that which is advanta geous to mankind; for bare power and knowledge, in themselves, exalt, rather than enrich human nature. We must, therefore, select from the general store, such things as are most useful to mankind. We shall have a better opportunity of discussing these when we treat of the application to practice; besides, in the work of interpretation, we leave room, on every subject, for the human or optative chart; for it is a part of science to make judicious inquiries and wishes.

50. In the twenty-sixth rank of prerogative instances, we will place the generally useful instances. They are such as relate to various points, and frequently occur, sparing, by that means, considerable labour and new trials. The proper place for treating of instances and contrivances, will be that in which we speak of the application to practice, and the methods of experiment. All that has hitherto been ascertained, and made use of, will be described in the particular history of each art. At present, we will subjoin a few general examples of the instances in question.

Man acts, then, upon natural bodies (besides merely bringing them together or removing them) by seven principal methods: 1. By the exclusion of all that impedes and disturbs; 2. By compression, extension, agitation, and the like; 3. By heat and cold; 4. By detention in a suitable place; 5. By checking or directing motion; 6. By peculiar harmonies; 7. By a seasonable and

proper alternation, series, and succession of all Any bodies, however, can easily be suspended these, or at least of some of them. under some such vessel as we have mentioned, which has occasioned our remarks upon the experiment.

I. With regard to the first; common air, which is always at hand, and forces its admission, as also the rays of the heavenly bodies, create much disturbance. Whatever, therefore, tends to exclude them, may well be considered as generally useful. The substance and thickness of vessels in which bodies are placed when prepared for operations may be referred to this head. So, also, may the accurate methods of closing vessels by consolidation, or the latum sapientiæ, as the chymists call it. The exclusion of air by means of liquids at the extremity, is also very useful; as, when they pour oil on wine, or the juices of herbs, which, by spreading itself upon the top, like a cover, preserves them uninjured from the air. Powders, also, are serviceable, for, although they contain air mixed up in them, yet they ward off the power of the mass of circumambient air, which is seen in the preservation of grapes, and other fruits, in sand and flour. Wax, honey, pitch, and other resinous bodies, are well used in order to make the exclusion more perfect, and to remove the air and celestial influence. We have sometimes made an experiment, by placing a vessel or other bodies in quicksilver, the most dense of all substances capable of being poured round others. Grottos and subterraneous caves are of great use in keeping off the effects of the sun, and the predatory action of air, and, in the north of Germany, are used for granaries. The depositing of bodies at the bottom of water may be also mentioned here, and I remember having heard of some bottles of wine being let down into a deep well in order to cool them, but left there by chance, carelessness, and forgetfulness, for several years, and then taken out; by which means, the wine not only escaped becoming flat or dead, but was much more excellent in flavour; arising (as it appears) from a more complete mixture of its parts. But, if the case require that bodies should be sunk to the bottom of water, as in rivers, or the sea, and yet should not touch the water, nor be enclosed in sealed vessels, but surrounded only by air, it would be right to use that vessel which has been sometimes employed under water, above ships that have sunk, in order to enable the divers to remain below and breathe occasionally by turns. It was of the following nature. A hollow tub of metal was formed, and sunk so as to have its bottom parallel with the surface of the water; it thus carried down with it to the bottom of the sea all the air contained in the tub. It stood upon three feet, (like a tripod,) being of rather less height than a man, so that when the diver was in want of breath, he could put his head into the hollow of the tub, breathe, and then continue his work. We hear that some sort of boat or vessel has now been invented, capable of carrying men some distance under water.

Another advantage of the careful and hermetical closing of bodies is this; not only the admission of external air is prevented, (of which we have treated,) but the spirit of bodies also is prevented from making its escape, which is an internal operation. For any one operating on natural bodies must be certain as to their quantity, and that nothing has evaporated or escaped; since profound alterations take place in bodies, when art prevents the loss or escape of any portion, whilst nature prevents their annihilation. With regard to this circumstance, a false idea has prevailed, (which, if true, would make us despair of preserving quantity without diminution,) namely, that the spirit of bodies, and air when rarefied by a great degree of heat, cannot be so kept in by being enclosed in any vessel, as not to escape by the small pores. Men are led into this idea by common experiments of a cup inverted over water, with a candle or piece of lighted paper in it, by which the water is drawn up, and of those cups which when heated draw up the flesh. For they think that in each experiment the rarefied air escapes, and that its quantity is therefore diminished, by which means the water or flesh rises by the motion of connexion. This is, however, most incorrect. For the air is not diminished in quantity, but contracted in dimensions,* nor does this motion of the rising of the water begin till the flame is extinguished, or the air cooled, so that physicians place cold sponges, moistened with water, on the cups, in order to increase their attraction. There is, therefore, no reason why men should fear much from the ready escape of air: for, although it be true that the most solid bodies have their pores, yet neither air nor spirit readily suffers itself to be rarefied to such an extreme degree; just as water will not escape by a small chink.

II. With regard to the second of the seven above mentioned methods, we must especially observe, that compression and similar violence have a most powerful effect either in producing locomotion, and other motions of the same nature, as may be observed in engines and projectiles, or in destroying the organic body and those qualities which consist entirely in motion, (for all life, and every description of flame and ignition are destroyed by compression, which also injures and deranges every machine;) or in destroying those qualities which consist in position and a coarse difference of parts, as in colours; for the

* Part of the air is expanded and escapes, and part is consumed by the flame. When condensed, therefore, by the cold application, it cannot offer sufficient resistance to the external atmosphere to prevent the liquid or flesh from being forced into the glass.

master of violent motions than of any other means.

III. The third of our seven methods is referred to that great practical engine of nature as well as of art, cold and heat. Here man's power limps, as it were, with one leg. For we possess the heat of fire, which is infinitely more powerful and intense than that of the sun (as it reaches us) and that of animals. But we want cold,* except such as we can obtain in winter, in caverns, or by surrounding objects with snow and ice, which, per

tide heat of the sun in tropical countries, increased by the reflection of mountains and walls. For this degree of heat and cold can be borne for a short period only by animals, yet it is nothing compared with the heat of a burning furnace, or the corresponding degree of cold. Every thing with us has a tendency to become rarefied, dry, and wasted, and nothing to become condensed or soft, except by mixtures, and, as it were, spurious methods. Instances of cold, therefore, should be searched for most diligently, such as may be found by exposing bodies upon buildings in a hard frost, in subterraneous caverns, by surrounding bodies with snow and ice in deep places excavated for that purpose, by letting bodies down into wells, by burying bodies in quicksilver and metals, by immersing them in streams which petrify wood, by burying them in the earth, (which the Chinese are reported to do with their china, masses of which, made for that purpose, are said to remain in the ground for forty or fifty years, and to be transmitted to their heirs as a sort of artificial mine,) and the like. The condensations which take place in nature by means of cold should also be investigated, that by learning their causes they may be introduced into the arts; such as are observed in the exudation of marble and stones, in the dew upon the panes of glass in a room towards morning after a frosty night, in the formation and the gathering of vapours under the earth into water, whence spring fountains, and the like.

colour of a flower when whole differs from that it presents when bruised, and the same may be observed of whole and powdered amber; or in taste, for the taste of a pear before it is ripe and of the same pear when bruised and softened is different, since it becomes perceptibly more sweet. But such violence is of little avail in the more noble transformations and changes of homogeneous bodies, for they do not, by such means, acquire any constantly and permanently new state, but one that is transitory, and always struggling to return to its former habit and free-haps, may be compared in degree with the noondom. It would not, however, be useless to make some more diligent experiments with regard to this; whether, for instance, the condensation of a perfectly homogeneous body (such as air, water, oil, and the like) or their rarefaction, when effected by violence, can become permanent, fixed, and, as it were, so changed as to become a nature. This might at first be tried by simple perseverance, and then by means of helps and harmonies. It might readily have been attempted, (if we had but thought of it,) when we condensed water (as was mentioned above) by hammering and compression until it burst out. For we ought to have left the flattened globe untouched for some days, and then to have drawn off the water in order to try whether it would have immediately occupied the same dimensions as it did before the condensation. If it had not done so, either immediately or soon afterwards, the condensation would have appeared to have been rendered constant; if not, it would have appeared that a restitution took place, and that the condensation had been transitory. Something of the same kind might have been tried with the glass eggs; the egg should have been sealed up suddenly and firmly, after a complete exhaustion of the air, and should have been allowed to remain so for some days, and it might then have been tried whether, on opening the aperture, the air would be drawn in with a hissing noise, or whether as much water would be drawn into it when immersed, as would have been drawn into it at first, if it had not continued sealed. For it is probable (or at least worth making the experiment) that this might have happened, or might happen, because perseverance has a similar effect upon bodies which are a little less homogeneous. A stick bent together for some time does not rebound, which is not owing to any loss of quantity in the wood during the time, for the same would occur (after a larger time) in a plate of steel, which does not evaporate. If the experiment of simple perseverance should fail, the matter should not be given up, but other means should be employed. For it would be no small advantage, if bodies could be en lued with fixed and constant natures by violence. Air could then be converted into water by condensation, with other similar effects; for man is more the

Besides the substances which are cold to the touch, there are others which have also the effect of cold, and condense; they appear, however, to act only upon the bodies of animals, and scarcely any further. Of these we have many instances, in medicines and plasters. Some condense the flesh and tangible parts, such as astringent and inspissating medicines, others the spirits, such as soporifics. There are two modes of condensing

*Hent can now be abstracted by a very simple process, till the degree of cold be of almost any required intersity.

It is impossible to compare a degree of heat with a degree of cold, without the assumption of some arbitrary test, to which the degrees are to be referred. In the next sentence port heat or cold as the test, and then the comparison can only be between the degree of heat or of cold that will produce death.

Bacon appears to have taken the power of animal life to sup

degree of heat from a certain degree of cold.
The zero must be arbitrary which divides equally a certain

the spirits, by soporifics or provocatives to sleep; for from their investigation, unless the discovery the one by calming the motion, the other by of forms and conformation be attained. With expelling the spirit. The violet, dried roses, let-regard to animal bodies, it is not to be questioned tuces, and other benign or mild remedies, by their that there are many internal and external medifriendly and gently cooling vapours, invite the cines which condense by harmony, as we have spirits to unite, and restrain their violent and per- before observed, but this action is rare in inaniturbed motion. Rose-water, for instance, applied mate bodies. Written accounts, as well as reto the nostrils in fainting fits, causes the resolved port, have certainly spoken of a tree in one of the and relaxed spirits to recover themselves, and, as Tercera or Canary Islands (for I do not exactly it were, cherishes them. But opiates, and the recollect which) that drips perpetually, so as to like, banish the spirits by their malignant and supply the inhabitants, in some degree, with hostile quality. If they be applied, therefore, exter- water; and Paracelsus says, that the herb called nally, the spirits immediately quit the part, and no ros solis is filled with dew at noon, whilst the sun longer readily flow into it; but if they be taken gives out its greatest heat, and all other herbs internally, their vapour, mounting to the head, around it are dry. We treat both these accounts expels, in all directions, the spirits contained in as fables; they would, however, if true, be of the ventricles of the brain, and since these spirits the most important service, and most worthy of retreat, but cannot escape, they consequently examination. As to the honey-dew, resembling meet and are condensed, and are sometimes com- manna, which is found in May on the leaves of pletely extinguished and suffocated; although the the oak, we are of opinion that it is not condensed same opiates, when taken in moderation, by a by any harmony or peculiarity of the oak leaf, but secondary accident, (the condensation which suc- that whilst it falls equally upon other leaves, it ceeds their union,) strengthen the spirits, render is retained and continues on those of the oak, bethem more robust, and check their useless and cause their texture is closer, and not so porous as inflammatory motion, by which means they con- that of most of the other leaves.* tribute not a little to the cure of diseases, and the prolongation of life.

The preparations of bodies, also, for the reception of cold, should not be omitted, such as that water a little warmed is more easily frozen than that which is quite cold, and the like.

With regard to heat, man possesses abundant means and power, but his observation and inquiry are defective in some respects, and those of the greatest importance, notwithstanding the boasting of quacks. For the effects of intense heat are examined and observed, whilst those of a more Moreover, since nature supplies cold so sparing- gentle degree of heat, being of the most frequent ly, we must act like the apothecaries, who, when occurrence in the paths of nature, are, on that very they cannot obtain any simple ingredient, take account, least known. We see, therefore, the a succedaneum, or quid pro quo, as they term it, furnaces, which are most esteemed, employed in such as aloes for xylobalsamum, cassia for cinna- increasing the spirits of bodies to a great extent, mon. In the same manner we should look dili- as in the strong acids, and some chymical oils; gently about us, to ascertain whether there may whilst the tangible parts are hardened, and, when be any substitutes for cold, that is to say, in what the volatile part has escaped, become sometimes other manner condensation can be effected, which fixed; the homogeneous parts are separated, and is the peculiar operation of cold. Such conden- the heterogeneous incorporated and agglomerated sations appear hitherto to be of four kinds only. in a coarse lump; and (what is chiefly worthy of 1. By simple compression, which is of little avail remark) the junction of compound bodies, and towards permanent condensation, on account of the more delicate conformations are destroyed and the elasticity of substances, but may still how- confounded. But the operation of a less violent ever be of some assistance. 2. By the contrac- heat should be tried and investigated, by which tion of the coarser, after the escape or departure more delicate mixtures and regular conformations of the finer parts of a given body; as is exempli- may be produced and elicited, according to the fied in induration by fire, and the repeated heating example of nature, and in imitation of the effect and extinguishing of metals, and the like. 3. By of the sun, which we have alluded to in the he cohesion of the most solid homogeneous parts aphorism on the instances of alliance. For the of a given body, which were previously separated, works of nature are carried on in much smaller and mixed with others less solid, as in the return portions, and in more delicate and varied positions of sublimated mercury to its simple state, in than those of fire, as we now employ it. But which it occupies much less space than it did in man will then appear to have really augmented powder, and the same may be observed of the his power, when the works of nature can be cleansing of all metals from their dross. 4. By imitated in specie, perfected in power, and varied harmony or the application of substances which in quantity; to which should be added the accecondense by some latent power. These harmo- leration in point of time. Rust, for instance, is nies are as yet but rarely observed, at which we cannot be surprised, since there is little to hope

It may often be observed on the leaves of the lime and

other trees.

the result of a long process, but crocus Martis is obtained immediately; and the same may be observed of natural verdigris and ceruse. Crystal is formed slowly, whilst glass is blown immediately stones increase slowly, whilst bricks are baked immediately, &c. In the mean time (with regard to our present subject) every different species of heat should, with its peculiar effects, be diligently collected and inquired into; that of the heavenly bodies, whether their rays be direct, reflected, or refracted, or condensed by a burning-glass; that of lightning, flame, and ignited charcoal; that of fire of different materials, either open or confined, straitened or overflowing, qualified by the different forms of the furnaces, excited by the bellows, or quiescent, removed to a greater or less distance, or passing through different media; moist heats, such as the balneum Mariæ, and the dunghill; the external and internal heat of animals; dry heats, such as the heat of ashes, lime, warm sand; in short, the nature of every kind of heat, and its degrees.

We should, however, particularly attend to the investigation and discovery of the effects and operations of heat, when made to approach and retire by degrees, regularly, periodically, and by proper intervals of space and time. For this systematical inequality is in truth the daughter of heaven and mother of generation, nor can any great result be expected from a vehement, precipitate, or desultory heat. For this is not only most evident in vegetables, but in the wombs of animals, also, there arises a great inequality of heat, from the motion, sleep, food, and passions of the female. The same inequality prevails in those subterraneous beds where metals and fossils are perpetually forming, which renders yet more remarkable the ignorance of some of the reformed alchymists, who imagined they could attain their object by the equable heat of lamps, or the like, burning uniformly. Let this suffice concerning the operation and effects of heat; nor is it time for us to investigate them thoroughly before the forms and conformations of bodies have been further examined and brought to light. When we have determined upon our models, we may seek, apply, and arrange our instru


wasted by the lapse of ages. The incorporations and mixtures, which are hurried by fire, are very inferior to those obtained by continuance; and the various conformations assumed by bodies left to themselves, such as mouldiness, &c., are put a stop to by fire or a strong heat. It is not, in the mean time, unimportant to remark, that there is a certain degree of violence in the motion of bodies entirely confined. For the confinement impedes the proper motion of the body. Continuance in an open vessel, therefore, is useful for separations, and in one hermetically sealed for mixtures, that in a vessel partly closed, but admitting the air for putrefaction. But instances of the operation and effect of continuance must be collected diligently from every quarter.

V. The direction of motion (which is the fifth method of action) is of no small use. We adopt this term when speaking of a body, which, meeting with another, either arrests, repels, allows, or directs its original motion. This is the case principally in the figure and position of vessels. An upright cone, for instance, promotes the condensation of vapour in alembics, but, when reversed, as in inverted vessels, it assists the refining of sugar. Sometimes a curved form or one alternately contracted and dilated is required. Strainers may be ranged under this head, where the opposed body opens a way for one portion of another substance and impedes the rest. Nor is this process, or any other direction of motion, carried on externally only, but sometimes by one body within another. Thus, pebbles are thrown into water to collect the muddy particles, and syrups are refined by the white of an egg, which glues the grosser particles together so as to facilitate their removal. Telesius, indeed, rashly and ignorantly enough attributes the formation of animals to this cause, by means of the channels and folds of the womb. He ought to have observed a similar formation of the young in eggs, which have no wrinkles or inequalities. One may observe a real result of this direction of motion in casting and modelling.

VI. The effects produced by harmony and aversion (which is the sixth method) are frequently buried in obscurity. For these occult and specific properties, (as they are termed,) the sympathies and antipathies are for the most part but a corruption of philosophy. Nor can we form any great expectation of the discovery of the harmony which exists between natural objects, before that of their forms and simple conformations, for it is nothing more than the symmetry between these forms and conformations.

IV. The fourth mode of action is by continuance, the very steward and almoner, as it were, of nature. We apply the term continuance to the abandonment of a body to itself for an observable time, guarded and protected in the mean while from all external force. For the internal motion then commences to betray and exert itself when the external and adventitious is The greater and more universal species of harremoved. The effects of time, however, are far mony are not, however, so wholly obscure, and more delicate than those of fire. Wine, for with them, therefore, we must commence. The instance, cannot be clarified by fire as it is by first and principal distinction between them is continuance. Nor are the ashes produced by this; that some bodies differ considerably in the combustion so fine as the particles dissolved or abundance and rarity of their substance, but cor

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