1 C E 
V 
pact umbel ^ they are of a purple colour, and ap- 
pear in June, but are feldom fucceeded by feeds in 
England. 
It is propagated by feeds, which fhould be fown on 
a ihady border in autumn, and when the plants are 
ftrong enough to remove, they fhould be tranfplanted 
on a fhady border where they are defigned to remain, 
and will require no other care but to keep them clean 
from weeds. 
The eighth fort grows naturally in Spain and Portu- 
gal , this hath a great reiemblance of the fecond, but 
the ftalks do not fpread fo much ; they grow erect, 
about feven or eight inches high, are ligneous and pe- 
rennial. The leaves are very narrow, and feldom 
more than an inch long, ftanding thinly upon the 
ftalks, having no foot-ftalks. The flowers grow in 
hemifpherical umbels on the top of the italics, and 
are of a purple colour. It flowers in May and June, 
but feldom produces good feeds here. 
This fort may be propagated by cuttings, which 
fhould be treated In the fame way as is before di- 
rected for the firft fort ; and fome of the plants may 
be planted on a warm border in a dry foil, where they 
will endure the cold of our ordinary winters very well j 
but it will be proper to have two or three plants in 
pots, which may be fheltered under a frame in win- 
ter, to preferve the kind, if, by fevere froft, thofe in 
the open air fhould be deflroyed. 
IBISCUS. See Hibiscus. 
I C A C O. See Chyrsobalanus, 
ICE is a hard tranfparent body, formed from fome 
liquor congealed, or fixed. 
Ice is faid to be the natural ftate of water, which re- 
mains firm, and not liquid, when no external caufe 
a£ts upon it. 
The true caufe of the congelation of water into Ice, 
feems to be the introduction of frigorific particles into 
the pores or interfaces between the particles of -wa- 
ter, and by that means getting fo near them, as to 
be juft within the fpheres of one another’s attrac- 
tions, and then they muft cohere into one folid or 
firm body. 
It may be wondered why Ice goes to the top of the 
water, for one would imagine, that being colder than 
flowing water, it ought to be more condenfed, and 
confequently heavier ; but is to be confidered, that 
there are always fome bubbles of air interlperfed in 
Ice. It is certain, by the fvimming of Ice upon wa- 
ter, that it is fpecifically lighter than the water out of 
which it is made by freezing ; and it is as certain, 
that this lightnefs of Ice proceeds from thofe nu- 
merous bubbles that are produced in it by conge- 
lation. 
Water, when it is frozen into Ice, takes up more 
fpace than it did before it was congealed. It is vi- 
fible, that the dimenfions of water are increafed by 
freezing, its particles being, kept at fome diftance 
the one from the other, by the intervention of the 
frigorific matter. 
And, befides, there are many little volumes of air 
included at feveral diftances, both in the pores of the 
watery particles, and in the interfaces made by the 
fpherical figures. Now, by the infinuation of thefe 
chryftals, the volumes of air are driven out of the 
watery particles, and many of them uniting, form 
larger volumes ; thefe have thereby a greater force 
to expand themfelves than when they are difperfed, 
and fo both enlarge their dimenfions, and leffen the 
fpecific gravity of water thus congealed into Ice. 
It feems very probable, that cold, and freezing, and 
confequently Ice, are produced by fome fubftance of a 
faline nature floating in the air in that falts, and 
more eminently fome particular ones, when mixed 
with Ice or fnow, do wonderfully increafe the force 
and effects of cold. 
It is alfo vifible, that all faline bodies caufe a ftiff- 
nefs and frigidity in thofe bodies into which they 
enter. 
It is manifeft, by obferving falts by microfcopes, 
that the figures of fome falts, before they Ihoot into 
4 
1 G E 
maffes, are then double wedge-like particles, which 
have abundance of fnrface in refpecft to their folidity j 
and this is the reafon why they fw-itn in water, when 
once they are raffed in it, although they are Ipecifi- 
cally heavier, thefe fmall points of falts getting into 
the pores of the water, whereby they are, in fome 
meafure, fufpended in the winter, when the heat of 
the fun is not ordinarily ftrong enough to diffolve the 
falts into fluid, to break their points, and to keep 
them in perpetual motion *, which being Ids difturbed, 
are more at liberty to approach one another, and by 
ihoot ing into chryftals, of the form above-mentioned, 
do, by their extremities, infinuate themfelves into the 
pores of water, and by that means freeze it into a fo- 
lid form, called Ice. 
Monf. Mariotte, in his Ttfeatife of Hydroftatics, gives 
the fubfequent account of what happens to water in 
freezing, which he difcovered by the following expe- 
riment. 
Having filled a cylindric veffel, of about feven or 
eight inches high, and fix inches diameter, within two 
inches of the top, with cold water, he expofed it to 
the open air in a great froft, and obferved exactly the 
whole progrefs of the freezing of it. 
The firft congelation was in the upper furface of the 
water, in little long water fhoots, or laminae, which 
were jagged like a law, the water between them re- 
maining ftill unfrozen, though the reft of the furface 
was already frozen to the thicknefs of more than two 
lines ; he obferved that feveral bubbles of air were 
formed in the Ice, that began to fix on the bottom 
and Tides of the veffel, fome would rife up, and others 
remained entangled in the Ice, which made him ima- 
gine that thefe bubbles taking up more fpace in the 
water, than when their matter was, as it were, dif- 
folved in it, they pufhed up ,a little water through 
the hole at the top, after the fame manner that new 
wine works out at the bung-hole of a veffel when it 
begins to heat, and the little water that ouzed out at 
this little hole in the Ice, fpread ing itfelf upon the 
upper furface of the water, which was already frozen, 
became Ice alfo, and there began to form a hill of 
' Ice ; and that hole continuing open, by reafon of the 
water which palled fucceffively through it, being 
pufhed up by the new bubbles which formed them- 
felves in the Ice, which continue to increafe about 
the hides and bottom of the veffel, he obferved that 
the upper furface of the water was frozen above an 
inch thick towards the edges of the veffel, and 
above an inch and a half round about the little 
hole, before the water that was contained in it, as 
in a pipe, became frozen, but at laft it was frozen * 3 
then the middle of the water remaining unfrozen, 
and the water which was compreffed by the new 
bubbles, which formed themfelves for two or three 
hours, having no vent at the little hole, the Ice broke 
at once towards the top, by the fpring of the in- 
cluded air. 
In like manner the froft acls upon vegetables, by 
thefe frigorific particles entering the tender fhoots of 
plants, and infinuating between the pores of the fap, 
thereby increafing its bulk, fo that the tender veffels of 
the plants are torn, and thofe parts of the plants are 
foon killed ; and the greater the quantity of moifture 
is in vegetables, the more they are in danger of be- 
ing deftroyed, for we frequently fee many plants which 
grow on the top, and from the joints of walls, efcape 
the fevereft frofts, when thofe of the fame kinds are 
all deftroyed which were in the ground •, which is en- 
tirely owing to their veffels being ftronger and more 
compadl, and not fo replete with moifture : fo when 
the autumn proves cold and moift, whereby the vef- 
fels of plants are not properly hardened, and are re- 
plete with moifture, a fmall froft will do great mif- 
chief to them ; whereas when the autumn is dry and 
warm, the tender fhoots of trees and fhrubs are har- 
dened, and drained of their moifture, fo are not lia- 
ble to the like accidents. 
I C E-H O U S E is a building contrived to preferve ice 
for the ufe of affamily in the fummer feafon. 
Thefe 
