ICE, in physiology, a solid, transparent, and brittle body, formed of some fluid, particularly water, by means of cold. See FROST.
The younger Lemery observes, that ice is only a re-establishment of the parts of water in their natural state; that the mere absence of fire is sufficient to account for this re-establishment; and that the fluidity of water is a real fusion, like that of metals exposed to the fire; differing only in this, that a greater quantity of fire is necessary to the one than the other. Galileo was the first that observed ice to be lighter than the water which composed it: and hence it happens, that ice floats upon water, its specific gravity being to that of water as eight to nine. This rarefaction of ice seems to be owing to the air-bubbles produced in water by freezing; and which, being considerably large in proportion to the water frozen, render the body so much specifically lighter: these air-bubbles, during their production, acquire a great expansive power, so as to burst the containing vessels, tho' ever so strong. See CONGELATION, COLD, &c.
M. Mairan, in a dissertation on ice, attributes the increase of its bulk chiefly to a different arrangement of the parts of the water from which it is formed; the icy skin on the water being composed of filaments which are found to be constantly and regularly joined at an angle of 60°; and which, by this angular disposition, occupy a greater volume than if they were parallel. He found the augmentation of the volume of water by freezing, in different trials, a 14th, an 18th, a 19th, and, when the water was previously purged
ged of air, only a 22d part: that ice, even after its formation, continues to expand by cold; for, after water had been frozen to some thickness, the fluid part being let out by a hole in the bottom of the vessel, a continuance of the cold made the ice convex; and a piece of ice which was at first only a 14th part specifically lighter than water, on being exposed some days to the frost, became a 12th part lighter. To this cause he attributes the bursting of ice on ponds.
Wax, resins, and animal-fats, made fluid by fire, instead of expanding like watery liquors, shrink in their return to solidity: for solid pieces of the same bodies sink to the bottom of the respective fluids; a proof that these bodies are more dense in their solid than in their fluid state. The oils which congeal by cold, as oil-olive, and the essential oil of aniseeds, appear also to shrink in their congelation. Hence, the different dispositions of different kinds of trees to be burst by, or to resist, strong frosts, are by some attributed to the juices with which the tree abounds; being in the one case watery, and in the other resinous or oily.
Ice-House, a building contrived to preserve ice for the use of a family in the summer-season.
Ice-houses are more generally used in warm countries than with us; particularly in Italy, where the meanest person who rents a house, has his vault or cellar for ice.
As to the situation, it ought to be placed upon a dry spot of ground; because wherever there is moisture, the ice will melt: therefore in all strong lands which retain the wet, too much pains cannot be taken to make drains all round them. The place should also be elevated, and as much exposed to the sun and air as possible.
As to the figure of the building, that may be according to the fancy of the owner; but a circular form is most proper for the well in which the ice is to be preserved, which should be of a size and depth proportionable to the quantity to be kept: for it is proper to have it large enough to contain ice for two years consumption; so that if a mild winter should happen, in which little or no ice is to be had, there may be a stock to supply the want. At the bottom of the well, there should be a space of about two feet deep, left to receive any moisture that may drain from the ice; over this space should be placed a strong wooden grate, and from thence a small drain should be laid under ground to carry off the wet. The sides of the well should be built with brick or stone, at least two bricks thick; for the thicker it is, the less danger there will be of the well being affected by any external cause. When the wall is brought up within three feet of the surface, there should be another outer arch or wall begun, which should be carried up to the height of the top of the intended arch of the well; and if there be a second arch turned over this wall, it will add to the goodness of the house: the roof must be high enough above the inner arch to admit of a door-way to get out the ice. If the building is to be covered with slates or tiles, reeds should be laid considerably thick under them, to keep out the sun and external air; and if these reeds are laid the thickness of six or eight inches, and plastered over with lime and hair, there will be no danger of the heat getting through them. The external wall may be built in what form the pro-
prietor pleases; and as these ice-houses are placed in gardens, they are sometimes so contrived as to have an handsome alcove-seat in front, with a small door behind it, through which a person might enter to take out the ice; and a large door on the other side, fronting the north, with a porch wide enough for a small cart to back, in order to shoot down the ice near the mouth of the well, which need not be more than two feet diameter, and a stone so contrived as to shut it up in the exactest manner: all the vacant space above and between this and the large door should be filled up with barley-straw. The building thus finished, should have time to dry before the ice is put into it.
It is to be observed, that upon the wooden grate, at the bottom of the well, there should be laid some small faggots; and if upon these a layer of reeds is placed smooth for the ice to lie upon, it will be better than straw, which is commonly used. As to the choice of the ice, the thinner it is, the easier it may be broken to powder; for the smaller it is broken, the better it will unite when put into the well. In putting it in, care must be taken to ram it as close as possible; and also to allow a vacancy of two inches, all round, next the side of the well, to give passage to any moisture occasioned by the melting of some of the ice. When the ice is put into the well, if a little salt-petre be mixed with it at every ten inches or a foot in thickness, it will cause it to unite more closely into a solid mass.
Ice-Island, a name given by sailors to a great quantity of ice collected into one huge solid mass, and floating about upon the seas near or within the Polar Circles.—Many of these fluctuating islands are met with on the coasts of Spitzbergen, to the great danger of the shipping employed in the Greenland fishery. Towards the South Pole, they are still more numerous and formidable; but for a particular account of these islands and their formation, see the articles NORTH-SEA and SOUTH-SEA.