Volume I Part 2 (1/2)
Trans. Vol. LXV. And are so divided by membranes as to compose a very extensive surface, and are supplied with many pairs of nerves larger than any other nerves of the body; but how so large a quant.i.ty is so quickly acc.u.mulated as to produce such amazing effects in a fluid ill adapted for the purpose is not yet satisfactorily explained. The Torpedo possesses a similar power in a less degree, as was shewn by Mr. Walch, and another fish lately described by Mr. Paterson. Philo. Trans. Vol.
LXXVI.
In the construction of the Leyden-Phial, (as it is called) which is coated on both sides, it is known, that above one hundred times the quant.i.ty of positive electricity can be condensed on every square inch of the coating on one side, than could have been acc.u.mulated on the same surface if there had been no opposite coating communicating with the earth; because the negative electricity, or that part of it which caused its expansion, is now drawn off through the gla.s.s. It is also well known, that the thinner the gla.s.s is (which is thus coated on both sides so as to make a Leyden-phial, or plate) the more electricity can be condensed on one of its surfaces, till it becomes so thin as to break, and thence discharge itself.
Now it is possible, that the quant.i.ty of electricity condensible on one side of a coated phial may increase in some high ratio in respect to the thinness of the gla.s.s, since the power of attraction is known to decrease as the squares of the distances, to which this circ.u.mstance of electricity seems to bear some a.n.a.logy. Hence if an animal membrane, as thin as the silk-worm spins its silk, could be so situated as to be charged like the Leyden bottle, without bursting, (as such thin gla.s.s would be liable to do,) it would be difficult to calculate the immense quant.i.ty of electric fluid, which might be acc.u.mulated on its surface.
No land animals are yet discovered which possess this power, though the air would have been a much better medium for producing its effects; perhaps the size of the necessary apparatus would have been inconvenient to land animals.]
[_In his s.h.i.+ning claws_. l. 208. Alluding to an antique gem in the collection of the Grand Duke of Florence. Spence.]
V. 1. ”NYMPHS! Your soft smiles uncultur'd man subdued, 210 And charm'd the Savage from his native wood; You, while amazed his hurrying Hords retire From the fell havoc of devouring FIRE, Taught, the first Art! with piny rods to raise By quick attrition the domestic blaze, 215 Fan with soft breath, with kindling leaves provide, And lift the dread Destroyer on his side.
So, with bright wreath of serpent-tresses crown'd, Severe in beauty, young MEDUSA frown'd; Erewhile subdued, round WISDOM'S Aegis roll'd 220 Hiss'd the dread snakes, and flam'd in burnish'd gold; Flash'd on her brandish'd arm the immortal s.h.i.+eld, And Terror lighten'd o'er the dazzled field.
[_Of devouring fire_. l. 212. The first and most important discovery of mankind seems to have been that of fire. For many ages it is probable fire was esteemed a dangerous enemy, known only by its dreadful devastations; and that many lives must have been lost, and many dangerous burns and wounds must have afflicted those who first dared to subject it to the uses of life. It is said that the tall monkies of Borneo and Sumatra lie down with pleasure round any accidental fire in their woods; and are arrived to that degree of reason, that knowledge of causation, that they thrust into the remaining fire the half-burnt ends of the branches to prevent its going out. One of the n.o.bles of the cultivated people of Otaheita, when Captain Cook treated them with tea, catched the boiling water in his hand from the c.o.c.k of the tea-urn, and bellowed with pain, not conceiving that water could become hot, like red fire.
Tools of steel const.i.tute another important discovery in consequence of fire; and contributed perhaps princ.i.p.ally to give the European nations so great superiority over the American world. By these two agents, fire and tools of steel, mankind became able to cope with the vegetable kingdom, and conquer provinces of forests, which in uncultivated countries almost exclude the growth of other vegetables, and of those animals which are necessary to our existence. Add to this, that the quant.i.ty of our food is also increased by the use of fire, for some vegetables become salutary food by means of the heat used in cookery, which are naturally either noxious or difficult of digestion; as potatoes, kidney-beans, onions, cabbages. The ca.s.sava when made into bread, is perhaps rendered mild by the heat it undergoes, more than by expressing its superfluous juice. The roots of white bryony and of arum, I am informed lose much of their acrimony by boiling.]
[_Young Medusa frowned_. l. 218. The Egyptian Medusa is represented on antient gems with wings on her head, snaky hair, and a beautiful countenance, which appears intensely thinking; and was supposed to represent divine wisdom. The Grecian Medusa, on Minerva's s.h.i.+eld, as appears on other gems, has a countenance distorted with rage or pain, and is supposed to represent divine vengeance. This Medusa was one of the Gorgons, at first very beautiful and terrible to her enemies; Minerva turned her hair into snakes, and Perseus having cut off her head fixed it on the s.h.i.+eld of that G.o.ddess; the sight of which then petrified the beholders. Dannet Dict.]
2. NYMPHS! YOU disjoin, unite, condense, expand, And give new wonders to the Chemist's hand; 225 On tepid clouds of rising steam aspire, Or fix in sulphur all it's solid fire; With boundless spring elastic airs unfold, Or fill the fine vacuities of gold; With sudden flash vitrescent sparks reveal, 230 By fierce collision from the flint and steel; Or mark with s.h.i.+ning letter KUNKEL's name In the pale Phosphor's self-consuming flame.
So the chaste heart of some enchanted Maid s.h.i.+nes with insidious light, by Love betray'd; 235 Round her pale bosom plays the young Desire, And slow she wastes by self-consuming fire.
[_Or fix in sulphur_. l. 226. The phenomena of chemical explosions cannot be accounted for without the supposition, that some of the bodies employed contain concentrated or solid heat combined with them, to which the French Chemists have given the name of Calorique. When air is expanded in the air-pump, or water evaporated into steam, they drink up or absorb a great quant.i.ty of heat; from this a.n.a.logy, when gunpowder is exploded it ought to absorb much heat, that is, in popular language, it ought to produce a great quant.i.ty of cold. When vital air is united with phlogistic matter in respiration, which seems to be a slow combustion, its volume is lessened; the carbonic acid, and perhaps phosphoric acid are produced; and heat is given out; which according to the experiments of Dr. Crawford would seem to be deposited from the vital air. But as the vital air in nitrous acid is condensed from a light elastic gas to that of a heavy fluid, it must possess less heat than before. And hence a great part of the heat, which is given out in firing gunpowder, I should suppose, must reside in the sulphur or charcoal.
Mr. Lavoisier has shewn, that vital air, or Oxygene, looses less of its heat when it becomes one of the component parts of nitrous acid, than in any other of its combinations; and is hence capable of giving out a great quant.i.ty of heat in the explosion of gunpowder; but as there seems to be great a.n.a.logy between the matter of heat, or Calorique, and the electric matter; and as the worst conductors of electricity are believed to contain the greatest quant.i.ty of that fluid; there is reason to suspect that the worst conductors of heat may contain the most of that fluid; as sulphur, wax, silk, air, gla.s.s. See note on l. 174 of this Canto.]
[_Vitrescent sparks_. l. 229. When flints are struck against other flints they have the property of giving sparks of light; but it seems to be an internal light, perhaps of electric origin, very different from the ignited sparks which are struck from flint and steel. The sparks produced by the collision of steel with flint appear to be globular particles of iron, which have been fused, and imperfectly scorified or vitrified. They are kindled by the heat produced by the collision; but their vivid light, and their fusion and vitrification are the effects of a combustion continued in these particles during their pa.s.sage through the air. This opinion is confirmed by an experiment of Mr. Hawksbee, who found that these sparks could not be produced in the exhausted receiver.
See Keir's Chemical Dict. art. Iron, and art. Earth vitrifiable.]
[_The pale Phosphor_. l. 232. See additionable notes, No. X.]
3. ”YOU taught mysterious BACON to explore Metallic veins, and part the dross from ore; With sylvan coal in whirling mills combine 240 The crystal'd nitre, and the sulphurous mine; Through wiry nets the black diffusion strain, And close an airy ocean in a grain.-- Pent in dark chambers of cylindric bra.s.s Slumbers in grim repose the sooty ma.s.s; 245 Lit by the brilliant spark, from grain to grain Runs the quick fire along the kindling train; On the pain'd ear-drum bursts the sudden crash, Starts the red flame, and Death pursues the flash.-- Fear's feeble hand directs the fiery darts, 250 And Strength and Courage yield to chemic arts; Guilt with pale brow the mimic thunder owns, And Tyrants tremble on their blood-stain'd thrones.
[_And close an airy ocean_. l. 242. Gunpowder is plainly described in the works of Roger Bacon before the year 1267. He describes it in a curious manner, mentioning the sulphur and nitre, but conceals the charcoal in an anagram. The words are, sed tamen salis petrae _lure mope can ubre_, et sulphuris; et sic facies tonitrum, et corruscationem, si scias, artificium. The words lure mope can ubre are an anagram of carbonum pulvere. Biograph. Britan. Vol. I. Bacon de Secretis Operibus, Cap. XI. He adds, that he thinks by an artifice of this kind Gideon defeated the Midianites with only three hundred men. Judges, Chap. VII.
Chamb. Dict. art. Gunpowder. As Bacon does not claim this as his own invention, it is thought by many to have been of much more antient discovery.
The permanently elastic fluid generated in the firing of gunpowder is calculated by Mr. Robins to be about 244 if the bulk of the powder be 1.
And that the heat generated at the time of the explosion occasions the rarefied air thus produced to occupy about 1000 times the s.p.a.ce of the gunpowder. This pressure may therefore be called equal to 1000 atmospheres or six tons upon a square inch. As the suddenness of this explosion must contribute much to its power, it would seem that the chamber of powder, to produce its greatest effect, should be lighted in the centre of it; which I believe is not attended to in the manufacture of muskets or pistols.
From the cheapness with which a very powerful gunpowder is likely soon to be manufactured from aerated marine acid, or from a new method of forming nitrous acid by means of mangonese or other calciform ores, it may probably in time be applied to move machinery, and supersede the use of steam.
There is a bitter invective in Don Quixot against the inventors of gun- powder, as it levels the strong with the weak, the knight cased in steel with the naked shepherd, those who have been trained to the sword, with those who are totally unskilful in the use of it; and throws down all the splendid distinctions of mankind. These very reasons ought to have been urged to shew that the discovery of gunpowder has been of public utility by weakening the tyranny of the few over the many.]
VI. NYMPHS! You erewhile on simmering cauldrons play'd, And call'd delighted SAVERY to your aid; 255 Bade round the youth explosive STEAM aspire In gathering clouds, and wing'd the wave with fire; Bade with cold streams the quick expansion stop, And sunk the immense of vapour to a drop.-- Press'd by the ponderous air the Piston falls 260 Resistless, sliding through it's iron walls; Quick moves the balanced beam, of giant-birth, Wields his large limbs, and nodding shakes the earth.