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'C O L I^ rignlfies fomctaing devoid of heat, or which 

 docs not contain in it any particles of fire ; according 

 to which definiLion, cold is a mere negative term. 

 And this is agreeable to the fcntiments of moft of 

 our modern philofophcrs, who fuppofe cold to confilt 

 in a mere privation or diminution of heat. 

 Others much oh the fame principle, define cold, to 

 be that ftate of the minute parts of a body, wherein 

 they are agitated more flowly and faintly than thofe 

 of the organs of feeling. And in this fenfe, cold is 

 a mere term of relation : and hence the fame body 

 becomes liable to be perceived hot or cold, as the 

 - particles of it are in greater or lefler degree of motion 

 than thofe of the fenfible organ. 

 Heat is fuppofed to confift in a particular motion of 

 the parts of the body ; and hence the nature of cold, 

 v/hich is its oppofite, is eafily deducible -, for we find 

 that cold extinguiflies, or rather abates heat. Whence 

 it feems to follow, that thofe bodies are cold, which 

 check and rcflrain the motion of the particles, wherein 



heat confifts. 



There are three kinds of bodies that can do this •, 

 viz. either thofe whofe particles are perfeftly at reft •, 

 or thofe wbofe particles are indeed agitated, but with 

 Jefs violence than thofe of the hot body to which 

 "they are applied ; or, laftly, fuch whole particles 

 have a motion proper for excitifig the fenfation of 

 heat, but move with a different determination, fo as 

 to retard and change the motion of the particles of 



the organ. 



Hence three different kinds of cold, or cold bodies, 



do proceed. 



The A ft, That cold is common to all hard bodies j 



which confifts in the reft of their parts. 



The 2d is, That which rifes from plunging any part 



of the body in water ; which confifts in this, that the 



parts of our pfecordia, being more brifldy agitated 



than thofe of the fluid,, communicate part of their 



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motion to It.,, 



The 3d, The cold felt Cn' the CoUedion of warm air 

 with a pan, or in iDlowing hot breath out of our mouth 

 ' with the lips'^clofe fliut-, which confifts in this, that 

 the direft motion of the particles of air does, in fome 

 meafure, change and rebate the motion and determi- 

 nation of the parts of the body : and hence it is, 

 'that a cold body cannot cool another without heating 

 itfelf. _ ...... 



Hence alfo it proceeds, that the more the parts of a 

 frigid body are at reft, the more the particles of a 

 warm body that is applied to heat them, muft lofe of 

 their motion, and confequently of their heat. 

 Thus, there being mote quiefcent parts in marble 

 than in wood, which is full of pores and interftices, 

 the marble is felt colder than the wood : and hence 

 alfo we may underftand why air near marble, and 

 other derife bodies, feels fomewhat colder than in 

 other places. ' \ 



On this principle the two latter kinds of cold appear 

 fomewhat more than privations ; the particles in- 

 ducing the cold may be efteemed real frigorific cor- 

 pufcles ; and coldnefs may be deemed, a real quality, 

 as- well as hotncfs. Thefe particles do not only check 

 the agitation of thofe continually diffufed from the 

 inner parts of an animal to the outer ; but having an 

 claftic power, they bend, and hang about the fila- 

 ments of the body, pinch and fqueeze them ; and 

 hence is tTiat acute pungent fenfation called cold. 

 That cold is niore than a mere relation or comparifon, 

 is evident from its having real and pofitive effefts ; 

 fuch as freezing, congelation, condenfation, rarefac- 

 tion, burftin!2, '&c. 



Dr. Clarke rakes cold to be owing to certain nitrous 

 and other faline particles, endued with particular fi- 

 gures proper to jjroduce fuch cfFefts. Hence fal-ar- 

 moniac, fait pctre, fait of urine, and many other 

 volatile and alkalizate faks, mixed with water, in- 

 , crcaf:: its degree of cold very fenfibly. 

 Hence alfo comes that popular bbfcrvation, that cold 

 prevents corruption ; which, however, muft not be 

 adir/uted without aii exception j fince if an hard po- 



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rous body have Its interftices filled with water, and 

 this be too much dilated by freezing, the including 

 body will be burft. And thus it is that cold proves 

 deftruftive to the parts of fome plants : as it liappened 

 in the winters, anno 1728, and 1739-40, in feveral 

 trees, whofe trunks were much expofed to the fouth- 

 weft, the fap being thereby rarefied by the warmth 

 of the fun, which, for feveral days, at the beginning 

 of the fevere froft, ftione with an uncommon heat, 

 and the nights coming on to extreme cold, whereby 

 the rarefied fap was fo fuddenly condenfed, that the 

 fap-veffels could not contain it, and thereby burft off 

 the bark of many trees almoft from top to bottom ; 

 and this chiefly on the fouth-weft fide of the trees ; 

 as it did of feveral large trees in the phyfic-garden 

 at Chelfea -, and feveral Pear,^ and other fruit-trees, 

 in the nurferies of Mr. Francis Hunt at Putney, &c. 

 And thus it is that great quantities of trees are ren- 

 dered ftiaken, and the tirnber, when cut, of httle 

 value i which is generally the cafe in very fevere 

 winters. In the hard froft of the year 1739-40, there 

 was great damage done to the Oak-timber in moft 

 parts of England, by the froft penetrating to the fap- 

 veftels of the trees-, and by freezing the fap, the 

 veffels could not contain it, but burft with great 

 noife ; fo that the woods refounded with a noife fome- 

 what like the breaking down of the branches of trees, 

 when they are lopping. 



Dr. Boerhaave fiiys. That there is no fuch thing in 

 all nature as abfolute cold ; that the moft fevere he 

 had ever known, was in the year 1728, that then the 

 water would freeze while it ran down his hand ; and 

 yet even then the cold was not fo complete, but that 

 he could make an artificial cold o-reater by twelve 





Thobgh* much riiight be faid as to the effects of cold 

 on plants, I Ihall only conclude with an obfervation 

 of the Reverend Dr. Hales, who, in the conclufion 

 of his excellent treatile of Vegetable Statics, fays ; 

 The confiderable quantity of moifture/ which is per- 

 fpired from the branches of trees during the cold 

 winter feafon, plainly fliews the reafon why, in a long 

 feafon of cold north-eafterly winds, the bloffoms, and 

 tender young-fet fruit and leaves, are, in the early , 

 fpring, fo frequently blafted, viz. by having the 

 moifture exhaled fafter than can be fupplied from 

 the trees ; for, doubtlefs, moifture rifes flower from 

 the root, the colder the feafon is, though it rifes, in 

 fome degree, all the winter ; as is evident, as he fays, 

 from his fixteenth experiment in the faid book. 

 And from the fame caufe it is, that the leafy fpires 

 of Corn are by thefe cold drying winds often faded, 

 and turned yellow ; which makes the huflDandman, 

 on thefe occafions, wifli for fnow : which, though it ' 

 be very cold, yet it not only defends the root from 

 being frozen, but alfo fcreens the Corn from thefe 

 drying winds, and keeps it in a moift, florid, fupple 

 ftate. . V 



It feems therefore to be a reafonable diretStion, which 

 fome authors, who write on agriculture and gardening 

 give, viz. During thefe cold drying winds, when 

 little dew falls, to water the trees in dry foils, in the 

 blofl!bming feafon, and while the young-fct fruit is 

 tender ; and provided there is no immediate danger 

 of a froft, or in cafe of continued froft, to take care 

 to cover the trees well, and at the fame time to 

 fprinkle them with water; which is imitating na- 

 ture's method of watering eveiy part. 

 As to floping flickers over wall-trees he fays ; I have 

 often found, that when they are fo broad, as to pre- 

 vent any rain or dew coming at the trees, they do 

 more harm than good in thefe long eafterly dr>nn 

 winds, becaufe they prevent the rain and dews fallins 





cr 



on them •, which would not only refrefli and fupple 

 them, but alfo nourifli them : but in cafe of fl'^arp 

 froft after a fhower of rain, thefe flickers and other 

 fences muft needs be of excellent ufe to prevent the 

 almoft total deftrudion occafioned by the freezing of 

 the tender parts of vegetables, when they arc fa- 

 turated with moifture. • 



COLDENIA. 



