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The SECOND PART.

CHAP. I.

Ether confidered as elementary Fire, and its Nature under that Denomination inveftigated.

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N the preceding Part I have confider'd the electrical Medium chiefly as a fubtile elaftic Fluid, and, in its natural State, invisible; yet it may be render'd an Object of our Sight by means of the electrical Apparatus, where it appears under the form of real Fire, viz. not only luminous, but, as Dr. Franklin hath by judicious and well chofen Experiments clearly fhewn, endued with the most diftinguishing Criterion of Fire, even that of melting the hardeft Metals in an inftant. I fhall therefore here confider it under that Character, and fhall begin with a brief Definition of it, founded on its effential Properties as demonftrated by the foregoing Experiments.

A Definition of FIRE.

2. Firft. FIRE is an Element in the strictest Senfe of the Word, and confequently a permanent Z 2 Secondly.

Principle.

Secondly. That it is in form of an exceeding fine Air or Ether, and is, by means of Electricity, difcover'd to exist in the pores of all gross Bodies with which we are converfant.

Thirdly. True Fire fubfifts without a Pabulum, and confequently yields neither fmoke, Afbes, or any other grofs feculent Matter.

Fourthly. True Fire is either bot or cold according to the temperature of the Body in which it exifts.

*Here I expect to meet with the fame Fate which moft others have done, who, with an honeft oppo¬ fition to rooted prejudices have dared to advance paradoxical Truths.

Amongst the various methods adopted by fhallow Minds for the deciding of Controverfies, there is none more frequently made ufe of by them, than what is commonly term'd the HORSE-LAUGH. This, like an impetuous Torrent, carries all before it; no Remonftrance of Reason, no strength of Are gument can obtain the leaft hearing in the tumultuous Uproar; nor fhall I at all wonder if I experience fuch Treatment my felf from the unthinking and prepoffefs'd Multitude, in whofe injudicious and unphilofophical Ears cold Fire may found as the higheft Abfurdity, a contradiction in very Terms. But the approbation of fuch incompetent Judges is what I am not fo ambitious of as to offer an obla tion, coftly as Truth, at the Altars which their Fancies have erected. To my inquifitive, difcerning, and unbiafs'd Readers I addrefs my Difquifitions on this intricate Subject, well knowing that they will examine with Temper, and decree with Juftice.

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3. The Author thought a pofitive Definition of true Fire to be neceffary, fince elementary Fire is a Term frequently met with, but yet not always underftood even by those who use it, and is therefore often taken in a vague fenfe, and in different meanings: I have therefore confin'd it to that particular and reftrain'd fenfe which only it properly bears; no Fire having a right to the epithet pure, but that which fubfifts without a Pabulum and yields neither fmoke nor Ashes ; nor did we know of any that had the leaft pretenfion to fuch purity befides the folar, till we were agreeably furprised by the discovery of the electrical Fire.

A Definition of HEAT.

4. HEAT is an accidental Property or Quahity of Fire, generated at pleafure by the mutual Attrition of the Particles of the Fire: Or in other words, when Heat is produced by the Attrition of two Bodies, the ftrict and proper Caufe of fuch Heat is the mutual Attrition of the Particles of the Fire contain'd in thofe Bodies.

Illuftration.

1.5. Hence Heat is generated, increased, and continued in proportion to the violence and continuance of the mutual Attrition of the particles of the Fire; and we fhall have fufficient reafon to believe (when we come to fhew the method by which the greatest Heat was produced that was ever known*) that if it were That produced by Villette's Mirrour.

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poffible to diveft any two Bodies of the Fire contain'd in their pores or interstices, no Heat at all would be produced by the Friction, tho ever fo violently, and ever fo long continued.

6. Hence also, tho' the vulgar Expreffion, Hot as Fire, implies that heat is the very ef fence of it, yet, if we do but look back and reflect on the effects of the foregoing Experiments, we shall behold a cloud of Witneffes, all of them ready to teftify, that heat is not an effential property of Fire, for Fire is not always hot, even when capable of melting metals, if effected by Electricity.Dr. Franklin melted brafs Pins and fteel Needles, Gold and Glafs :

And tho'' fays he 'I have taken up the pieces ⚫ of Glafs between my fingers immediately after this melting, I never could perceive the leaft warmth in them.' Dr. Franklin's Letters, p. 66.

7. Again, tho' Water is naturally cold, yet we find the pores of nothing more plentifully ftored with Fire than thofe of Water, nor is there any one thing befides metals, from which pure Fire can be fo plentifully obtain'd: Since then, it always fubfifts in Water while in a fluid form, who can doubt the truth of the Affertion of that great Experimentalift Dr. Boerhaave, viz. that an incredible quantity of Fire is con<tain'd in the coldeft maffes of Ice, and may be inftantly produced from them with a great deal of violence *??

*Boerhaave's Elements of Chymistry, p. 81, Daliowe's Tranflation,

8.

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8. The ingenious American fo frequently mentioned made more Experiments with this fubtile Medium, and difcover'd more of its properties as Fire, than ever was known to be done before by any one in Europe.- He informs us that he had five large glass Jarrs, which held eight or nine gallons a piece, each of which required a thousand turns of a Globe nine Inches in diameter to charge it; but, faith he, I can charge and discharge them all together, as one. With the Fire obtain'd by this method, I have melted brafs Pins, and fteel Needles, inverted the Poles of the magnetic Needle, given a magnetism and polarity to Needles that had none before, and inverted the Poles at pleafure*, fired dry Gunpowder, &c. Two, of thefe Jarrs, when charged, are sufficient for thefe purpofes.Sometimes the Needles are finely blued like a Watch-spring; at other times melted.' He informs his Friend Mr. Collinfon, that he had fent him fome, with their heads and points melted off by his mimic Lightning; and a Pin, with its point melted off, and fome part of its head and neck rum. Sometimes the furface on the body of the Needle is also run, and appears blifter'd. 'I fend you faith he, two fpecimens of Tin-foil melted by the force of two Jarrs only. There are no bounds, (but what expence and labour give,) to the

* Who then can reasonably doubt whether the magnetic Virtue and the electric Virtue be from the fame Caufe, or not, i. e. the univerfal Æther or Fire? 'force,

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