heaviest Bodies, as alfo by the Action of many large Bellows brifkly wrought, and all confpiring to one Centre, or Focus: but the last effect of fuch Fire is in Animals, to produce Phosphorus, in Vegetables to make Glafs, and in Foffils to melt the moft fixed Gold.

P. 364. The Author proceeds to confider another Mixture way of collecting, and preferving Heat, in a given of Bodies collect Heat Place, viz. by the mixture of different Bodies, which he illuftrates in divers chemical Liquors. E. gr. diftill'd Rain-water, mixed with Spirit of Wine under different Circumftances and Degrees of Purity; Water mixed with Wine; Water with dif tilled Vinegar; Water with Oil of Tartar; Water with Oil of Turpentine; Alcohol with Etherial Oil of Turpentine; diftilled Vinegar with Oil of Turpentine, Vinegar with Alcohol; Oil of Tartar with Oil of Turpentine; Vinegar with Oil of Tartar. And from the CircumItances thereof, infers that all the Simples which Chemistry produces from Vegetables have naturally the fame Degree of Heat, viz. the fame with that of common Air at that time; that fome of the Fluids above-mention'd only acquire a greater Heat at the time of their mixture, which being compleated, they gradually return to the Temperature of the Atmosphere; that this Acceffion of Heat does not arife out of the Subftance of the Bodies mixed, but from their accidental Combination; that Alcohol and Water are the chief vegetable Fluids which have this Faculty of generating Heat; that Salt of Tartar and Water are the chief Solids and Fluids which by their mixture together generate Heat; and Alcohol and Salt of Tartar the next after these.

He

He proceeds further to exemplify the Production of Heat by mixtion, in the Inftances of Bodies of all the other Kingdóms; E. gr. Animal Subftances mixed with Vegetables; as Urine with Alcohol: of Foffils mixed with Foils; as Water with Nitre of cold Bodies heated by the mere accefs of the Air, as in the feveral kinds of Phofphorus of Fofils heated by means of Water, as in Iron-Filings, and Sulphur, which being mixed with Water, produce artificial Earthquakes and Volcanoes.

Bodies.

From the whole he collects many Particulars 386. concerning the Nature and Properties of the Particles of elementary Fire. As, their Corporeity, which follows from their being extended, moveable, capable of being at reft, and refisting the Impulse of other Bodies; their Subtility, which appears from their penetrating the denfeft Bodies; their Solidity, Smoothness, Simplicity, perpetual Mobility, &c. Elementary Fire he Fire the further afferts, is every where the fame in allfame in all hot Bodies, after what manner foever it have 402. been produced, and with whatsoever Fuel fuftained: fo that it is a groundless Complaint of the generality of Chemifts, that they can have no pure Fire to perform their Operations withal, as imagining I know not what Cæleftial, Solar, Aftral, Incorruptible Fire neceffary. In reality, Heat, whether generated in the Bodies of Animals, Vegetables, or Foffils, arifes always from the fame Fire; and when it has paffed thro' the Pores of Glass, is equally pure with the pureft Sun-beams. Thus the Heats of kindled Alcohol and of Pit-Coal, acting on a Matter included in a Veffel hermetically fealed, provided the degree of Heat be the fame in both, and applied in the fame manner, will always have the fame No. XVI. 1732. Bb Effect. VO E. III.

Fire, whence.

Effect of
Fire in

Effect. Not but the different Fuel on which Fire is fed makes an Alteration in its Effects, as it renders it ftronger or weaker, and even mixes fome of its Parts therewith; in refpect whereof, Purity of that Fire may be faid to be the fureft, which is raised and fuftained by burning Alcohol; then, that of diftilled Oils; then Naphtha and Petroleum; after thefe, that of Charcoal, then Wood, Turf, and laftly Pit-Coal, and Dang.For the Ufe and Effect of Fire in Chemistry, he fhews that it is by no means an univerfal SolChemifry vent of all Bodies, as ufually imagined, but acP. 405. cording to the different Degrees of it produces different Effects on the fame Body: nor is it a fincere Diffolvent, but adds many things to Bodies at the time it feparates others: nor does it act fenfibly on all Bodies, but leaves many as it were untouched, E. gr. Gold and Glafs. Nor are the Principles into which it reduces Bodies, pure and fimple, but variously mixed and combined with each other: add, that it compounds Bodies as well as diffolves, E. gr. Sand and fixed Alcali into Glafs. In fine, according to the different Manner of Application, the Effect of Fire is alfo different; as whether it be expofed naked to the Air, or covered from it: fo, the different Degrees of the fame Fire have alfo different Effects on the fame Body.

412.

It remains that the Author prefcribe Rules Direction whereby the Chemift may be enabled to judge of Fire. of the Fire prefent in any given place, and either excite, direct, fuftain, or apply it in a proper manner to produce the defired Effect.

Fire.

Degrees of The antient Chemifts confidered four Degrees of Fire, to which the Moderns have added two more, and at the fame time have better afcertained the Manner of eftimating them, by the

discovery

difcovery of the Thermometer. The first Degree of Fire is that which Nature ufes in the Vegetation of Plants, which is that, in Fabrenbeit's Thermometer, denoted by eighty Degrees, from the Point of utmoft Cold. The fecond Degree may be defined from the Heat of a human Body in a State of Health, marked in the Thermometer above mentioned by ninety-four Degrees. The third extends from ninety-four Degrees to two-hundred and twelve, which is the Heat of boiling Water. The fourth from twohundred and twelve, to fix hundred. The fifth from thence to the Degree which keeps Iron in Fufion. The fixth is that in the Focus of a Burning Glafs or Speculum.

The raifing of Fire to any defired Degree, and maintaining it therein, depends on the choice of a proper Fuel, the due Quantity and Distance. thereof; and laftly ftirring, and preffing it down.

The Author clofes his Account of Fire with a few Facts and Obfervations collected from other Writers, as the Journal des Scavans, the Philofophical Tranfactions, Sinclair, Sibbald, and Du Hamel: which, added to his own, he apprehends makes the Hiftory of Fire compleat.

In the Hiftory of Air, to which the Author now proceeds, we thall be more fummary, as being lefs new and original. We have here no new Doctrine broached, or even new Experiments, but only a Collection of what the Naturalists and Writers of Pneumaticks, Boyle and Mariotte, had produced, put in a better Form.

Air is an Inftrument of univerfal Ufe and Ef-Air. fect in all chemical Operations; as it is found P. 425. mixed with all Bodies, is contiguous alfo to

་

them, is neceffary to excite Fire, &c. In fine,

Properties.

no Life, Growth, or Action without it, either in Animals, Vegetables, or Foffils.

The Nature of Air on account of its great Subtilty, is difficult to difcover. Its Properties hiFluidity. therto found are, 1°. Fluidity, which arifes from the Tenuity and Lubricity of its Parts; alfo, the mutual Attraction between them, their Mifcibility with others, and their being impercepGravity. tible. 2o. Gravity, which of late days has been reduced to Rules, and the Effects thereof Elafticity. brought under Computation. 3°. Elafticity, or the Power of Expanding and Contracting, which is peculiar to this among all Fluids; the Laws of this Power, and the Steps whereby they were each discovered, are purfued largely by the Author. The Laws are, that Air contracts into lefs Space by how much it is preffed with a greater Weight; that this Property is unalterable by any Power whatever; that the Force of this Elafticity is equivalent to that of the Weight of the Atmosphere; and that the Power is increased by increafing the Degree of Heat.

Fire, Wa

ser.

461. The Contents of the Air or Atmosphere, are, Contents 1°. Fire, which is found in all Air. 2°. Water, of Air, which is alfo infeparable from Air, and may be procured from it various ways, making in reality the greatest part of the Bulk thereof. Hence Dew, Clouds, Rain, Springs, Rivers, Snow, Hail, Thunder and Lightning; the Origin and Formation of each whereof is traced Effluvia of by the Author. 3°. Effluvia of Bodies of all Vegetables.other kinds: viz. of the Vegetable Kingdom, we

find Spirits, both native and putrifactive; also Oils, Salts, and Earth, and even fometimes intire Parts of Plants, E. gr. Seeds, in the Air.Animals. Of Animal Matters, 'tis evident that Spirits, Excrements, nay all the other Parts thereof,

muft