722 I C 
•<quick motion to and fro, in the manner ufed for milling 
chocolate, for eight or ten minutes; then let it reft as 
long, and turn it again for the fame time; and having 
left it to Hand half an hour, it is fit to be turned out of 
the mould, and to be fent to table. Lemon-juice and 
fugar, and the juices of various kinds of fruits, are frozen 
without cream, and, when cream is ufed, it (hould be well 
mixed. 
Sir Robert Barker thus deferibes the procefs of making 
ice in the Eaft Indies, in a country where he never faw 
any natural ice. On a large plain they dig three or four 
pits, each about thirty feet fquare, and two feet deep; 
the bottoms of which are covered from eight to twelve in¬ 
ches thick, with fugar-cane, or the (terns of the large Indian 
corn, dried. On this bed are placed in rows a number of 
fmall (hallow unglazed earthen pans, formed of a very 
porous earth, a quarter of an inch thick, and about an 
inch and a quarter deep ; which, at the du(k of the even¬ 
ing, they fill with foft water that has been boiled. In 
the morning, before fun-rife, the ice-makers, attend at the 
pits, and colleft what has been frozen in bafkets, which 
they convey to the place of prefervation. This is ufually 
in fome high and dry fituation, by finking a pit fourteen 
or fifteen feet deep, which they line firft with ftraw, and 
then with a coarfe kind of blanketing. The ice is depo- 
fired in this pit, and beaten down with rammers, till at 
length its own accumulated cold again freezes it, and it 
forms one folid mat's. The mouth of the pit is well fe- 
cured from the exterior air with ftraw and blankets, and 
a thatched roof is thrown over the whole. Phil. Tranf. 
vol. Ixv. p. 252. 
Boerhaave alfo gives a method of producing artificial 
froft without either fnow or ice. We mull have for this 
purpofe, at any feafon of the year, the coldelt water that 
can be procured ; this is to be mixed with a proper quan¬ 
tity of any fait (fal ammoniac will anfwer the intention 
beft), at the rate of about three ounces to a quart of 
■water. Another quart of water mud be prepared in the 
fame manner with the firft; the fait, by being difi'olved 
in each, will make the water much colder than it was 
before. The two quarts are then to be mixed together, 
and this will make them colder (till. Two quarts more 
of water prepared and mixed in the fame manner are to 
be mixed with thefe, which will increafe the cold to a 
much higher degree in all. The whole of this operation 
is to be carried on in a cold cellar; and a glafs of com¬ 
mon water is then to be placed in the veflel of the fluid 
thus artificially cooled, and it will be turned into ice in 
the fpaee of twelve hours. 
There is alfo a method of making artificial ice by 
means of fnow, without any kind of fait. For this pur¬ 
pofe fill a fmall pewter difh with water, and Upon that 
.fet a common pewter plate filled, but not heaped, with 
fnow. Bring this Ample apparatus near the fire, and ftir 
the fnow in the plate : the fnow will, diflolve, and the ice 
will be formed on the back of the plate which was fet in 
the difh of water. 
. Mr. Reaumur tried the effeft of feveral falts, and exa¬ 
mined the various degrees of cold by an ice-thermometer, 
which, being placed in the fluid to be frozen, (bowed 
very exaftly the degree of cold by the defeent of the 
fpirit. Nitre, or faltpetre, ufually paffes for a lalt that 
'may be very ferviceable in thefe artificial congelations; 
but the experiments of this gentleman prove that this 
opinion is erroneous. The molt perfectly refined falt¬ 
petre employed in the operation funk the fpirit in the 
thermometer only three degrees and a half below the 
fixed point. Lefs refined nitre funk the thermometer 
lower, and gave a greater degree of cold; owing to the 
common or fea-falt that it contains when lefs pure, which 
has a greater effeft than the pure faltpetre itfelf. Two 
parts of common lalt being mixed with three parts of 
powdered ice in very hot weather, the fpirit in the thermo¬ 
meter immediately defeended fifteen degrees, which is half 
a degree lower than it would have ddceudeu in the fevereit 
E. 
cold of our winters. Mr. Reaumur then tried the frits 
all round, determining, with great regularity and exaft- 
ne(s, what was the degree of cold occalioned by each in 
a given dole. Among the neutral falts, none produced’ 
a greater degree of cold than the common lea-lalt. Among 
the alkalies, fal ammoniac (link the thermometer only to; 
thirteen degrees; pot-aflies funk it juft as low, as well 
refined faltpetre. 
For the common ufes of the table, the ice is not re¬ 
quired to be very hard, or luch as is produced by long 
continuance of violent cold: it is rather delired to be 
like (now. Saltpetie, which is no very powerful freezer, 
is therefore more fit for the purpofe than a more potent 
fait. It is not neceffary that the congelation (liould be 
very fuddenly made; but that it may retain its form as 
long as may be, when made, is of great importance. If 
it be defired to have ices very hard and firm, and very 
fuddenly prepared, then fea-falt is of all others moll to be 
cholen for the operation. The ices thus made will be 
very bard, but they will foon run. Pot-afiies afford an 
ice of about the hardnefs" that is ufually required : this 
forms indeed very (lowly, but then it will preferve a long 
time. Common wood-afhes will perform the bufineis 
very nearly in the fame manner as the pot-afnes; but, 
for this purpofe, the wood which is burnt ought to be 
frefli. 15 
The ftrong acid fpirits of the neutral falts aft much 
more powerfully in thefe congelations than the falts them- 
ielves, or indeed than any fimple fait can do. Thus, 
fpirit of nitre mixed with twice its quantity of powdered 
ice, immediately links the fpirit in the thermometer to 
nineteen degrees, or four degrees more than that obtained 
by means of fea-falt, the mod powerful of all the falts 
in making artificial cold. A much greater degree of cold 
may be given to this mixture, by piling it round with 
more ice mixed with fea-falt. This gives a redoubled 
cold, and finks the thermometer to twenty-four degrees. 
If this whole matter be covered with a frefh mixture of 
fpirit of nitre and ice, a (till greater degree of cold is 
produced, and fo on; the cold being by this method of 
frefli additions to be increafed almoft without bounds: 
but it is to be oblerved, that every addition gives a 
fmaller increafe than the former. 
It is very remarkable in the acid fpirits, that, though 
fea-frlt is lb much more powerful than nitre in lubftance 
in producing cold, yet the fpirit of nitre is much ftronger 
than that of fea-falt; and another not lefs wonderful phe¬ 
nomenon is, that fpirit of wine, which is little elfe than 
liquid fire, has as powerful an. effeft in congelations, or 
very nearly fo, as the fpirit of nitre itfelf. 
To ICE, v. a. To cover with ice; to turn to ice; to 
cover with concreted fugar. 
ICE-BLINK. See the article Greenland, vol. ix. p. c. 
ICE-BOAT, f. A boat fo conftrufted as to fail upon 
ice, very common in Holland, particularly upon the river 
Maefe and the lake Y. They go with incredible fwift- 
nefs, fometimes fo quick as to affeft the breath; and are 
found very ufeful in conveying goods and paffengers over 
lakes and great rivers in that country. Boats of diffe¬ 
rent fizes are placed in a tranfverfe form upon a two and 
a half or three inch deal board; at the extremity of each 
end are fixed irons, which turn up in the form of lkaits; 
upon this plank the boat refts, and the two ends feem as 
out-riggers to prevent overfetting; whence ropes are 
faftened that lead to the head of the malt in the nature 
ol fhrouds, and others are paffed through a block acrols 
the bowfprit: the rudder is made fomewhat like a hatchet 
with the head placed downward, which, being preffed 
down, cuts the ice, and ferves all the" purpofes of a rud¬ 
der in the water, by enabling the helmfman to fleer, 
tack, &c. 
ICE-BUILT, adj. Heaped with ice.—Where fiiaggy 
forms o’er ice-built mountains roam. Gray. 
ICE-HILLS. See p. 719. 
ICE-HOUSE, J. A repofitory for ice, efpecially during 
the 
