An essay on the first principles of natural philosophy. Wherein the use of natural means, or second causes, in the oeconomy of the material world, is demonstrated from reason, experiments of various kinds, and the testimony of antiquity : in four books illustrated with copper-plates / by the Reverend William Jones.

  • Jones, William, 1726-1800.
Date:
1762
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Licence: Public Domain Mark

Credit: An essay on the first principles of natural philosophy. Wherein the use of natural means, or second causes, in the oeconomy of the material world, is demonstrated from reason, experiments of various kinds, and the testimony of antiquity : in four books illustrated with copper-plates / by the Reverend William Jones. Source: Wellcome Collection.

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    done hiffing, in the water^ the heat of which was 5 3°; the thermometer was raifed to 150°. The mercury had a tempe¬ rature of 57°; but when the fame iron, heated as before, had been quenched in that, the thermometer was raifed beyond the heat of boiling water^ that is beyond 214°, and by the fwiftnefs with which it moved, I judged it woufd have gone much beyond the compafs of my inftrument; therefore I could not determine the exa6t degree of heat in this cafe, without making a thermometer on purpofe, which was not worth while. From the common refult of all the other ex¬ periments, the Tame cylinder of iron, having equal degrees of heat, communicates twice as much heat to mercury, as to an equal bulk of water; fo that the thermometer in this laft trial Would probaby have arifen beyond 240°. Who would have believed that jire fhould have an effedl equal to 14, where it ought, according to the common eftimation, .and the hypothefi^ of a vacuum^ to have an eiFe<Sl equal only to ' i ^ And that iron, when quenched in lb denfc a fluid as mercury, fhould remain fo many degrees hotter^ than when it is quenched in water *. The fpecific gravity of mercury being about 14 times greater than that of water, the quantity of matter in a given fpace, will be greater in the fame proportion. Now if there be an hiterfperfed •vacuum in thefe fluids; and if fire be nothing more than a certain vibtatory motion communicated to their particles ; then equal degrees of heat in any ignited body, ( as here in the cylinder of iron,) ought, by the laws of mechanics, to communicate 14 times as snuch mo¬ tion to a cubic inch of water, as to a cubic inch of mercury; whereas it doth really communi¬ cate only half fo much to the lighter ©f thefe, as it doth to the heavier. Therefore the fuperio- rity is on the wrong fide, and in the ratio of ig to or .14 to 1. But all this is natural enough, if fire is a fluid per fe, filling the interfperfed vacuities of other matter, and raifin|; a greater degree of heat, when it operates in a more confined fpace. ■ Water and mercury, being fluids by nature Ample, infipid, and uninflammable, arcj-of all others in the world, the fitteft for this experiment. If the fame trial were made on oils, fpirits, and other chemical liquors, which are inflammable, and impregnated with a fpirituous fire, m'^re eafy to be agitated; many curious and unexpefted varieties in the effeft might occur, concerning which, it may be unfafe to affirm any thing without due examination. ✓ Thus