G O L 
C OLD figniftes fome thing devoid of heat, or which 
does not contain in it any particles of fire ; according 
to which definition, cold is a mere negative term. 
And this is agreeable to the fentiments of moft of 
our modern philofophers, who fuppofe cold to confift 
in a mere privation or diminution of heat. 
Others much on the fame principle, define cold, to 
be that ftate of the minute parts of a body, wherein 
they are agitated more fiowly and faintly than thofe 
of the organs of feeling. And in this fenfe, cold is 
a mete 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, 
which is its oppofite, is eafily deducible ; for we find 
that cold extinguifhes, or rather abates heat. Whence 
it feems to follow, that thofe bodies are cold, which 
check and reftrain the motion of the particles, wherein 
heat con lifts . 
There are three kinds of bodies that can do this ; 
viz. either thofe whofe particles are perfedly at reft •, 
or thofe whofe particles are indeed agitated, but with 
lefs violence than thofe of the hot body to which 
they are applied •, or, laftly, fuch whofe particles 
have a motion proper for exciting 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 :ft, That cold is common to all hard bodies-, 
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 pratcordia, being more brifkly agitated 
than thofe of the fluid, communicate part of their 
motion to it. 
The yd, The cold felt on the colledion of warm air 
with a pan, or in blowing hot breath out of our mouth 
with the lips clofe fhut ; which confifts in this, that 
, the dired 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, muff: lofe of 
their motion, and confequently of their heat. 
Thus, there being more quiefcent parts in marble 
than in wood, which is full of pores and interfaces, 
the marble is felt colder than the wood : and hence 
alfo we may underftand why air near marble, and 
other denfe 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 hotnefs. 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 
elaftic power, they bend, and hang about the fila- 
ments of the body, pinch and fqueeze them ; and 
hence is that acute pungent fenfation called cold. 
That cold is more than a mere relation or comparifon, 
is evident from its having real and pofitive effeds ; 
fuch as freezing, congelation, condenfation, rarefac- 
tion, burfting, &c. 
Dr. Clarke takes cold to be owing to certain nitrous 
and other faline particles, endued with particular fi- 
gures proper to produce fuch effects. Hence fal-ar- 
moniac, fait petre, fait of urine, and many other 
volatile and alkalizate falts, mixed with water, in- 
creafe its degree" of cold very fenfibly. 
’ Hence alfo comes that popular obfervation, that cold 
prevents corruption y which, however, muft not be 
admitted without an exception ; fince if an hard pb- 
i 
COL 
rous body have its interfaces filled with water, and 
this be too much dilated by freezing, the including 
body will be burft. And thus it is that cold proves 
tie fti u ctive to the parts of fome plants : as it happened 
m the winters, anno 1728, and 1739-40, in feveral 
trees, whofe trunks were much expofed to the fouth- 
weft, the lap being thereby rarefied by the warmth 
of the fun, which, for feveral days, at the beginning 
of the fevere froft, fhone with an uncommon heat, 
and the nights coming on to extreme cold, whereby 
the rarefied fap was fo fuddenly condenfed, that the 
fap-veflels 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 5 
as it did of feveral large trees in the phylic-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 fhaken, and the timber, when cut, of little 
value ; 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- 
veflels of the trees ; and by freezing the fap, the 
veflels 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 fays, 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 greater by twelve 
degrees. 
Though much might be faid as to the effeds of cold 
on plants, I fhall only conclude with an obfervation 
of the Reverend Dr. Hales, who, in the conclufion 
of his excellent treatife of Vegetable Statics, fays ; 
The confiderable quantity of moifture, which is per- 
fpired from the branches of trees during the cold 
winter feafon, plainly fhews the reafon why, in a long 
feafon of cold north-eafterly winds, the blofibms, 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 hufbandman, 
on thefe occafions, wifh for fnow : which, though it 
be very cold, yet it not only defends the root from 
being frozen, but alfo fcreens the Com from thefe 
drying winds, and keeps it in a moift, florid, fupple 
ftate. 
It feems therefore to be a reafonable diredion, 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 
bloffoming feafon, and while the young-fet 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 every part. 
As to Hoping fhelters 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 drying 
winds, becaufe they prevent the rain and dews falling 
on them ; which would not only refrefh and fupple 
them, but alfo nourifh them : but in cafe of fharp 
froft after a fhower of rain, thefe fhelters and other 
fences muft needs be of excellent ufe to prevent the 
almoft total deftrudion occafloned by the freezing of 
the tender parts of vegetables, when they are fa- 
turated with moifture. 
COLDENIA. 
