in physiology, such an excessively cold state of the air as converts watery fluids into ice.

In very cold snowy weather, not only water, but urine, beer, ale, milk, vinegar, and even wine, are either wholly or in part converted into ice, though the last but slowly. As to the freezing of expressed oils, a very intense cold may deprive them of their fluidity, so as to be capable of being cut into portions of any figure; but whether they are convertible into real ice, is not yet determined. In Russia oil freezes much harder than with us, but does not even there become perfect ice. Common anniseed-water, and the like weak spirits, are said to be converted into an imperfect ice in Muscovy; and the strong spirits into a substance like that of oil. When brandy freezes, a liquid part, much stronger than common brandy, retires to the centre of the vessel.

Even solid bodies are liable to be affected by frost: timber is often apparently frozen, and rendered exceedingly difficult to saw. Marle, chalk, and other less solid terrestrial concretions, will be shattered by strong and durable frosts. Metals are contracted by frost: thus, an iron tube, twelve foot long, upon being exposed to the air in a frosty night, lost two lines of its length. On the contrary, it swells or dilates fluids near one tenth of their bulk. Mr Boyle made several experiments with metallic vessels, exceeding thick and strong; which being filled with water close stopped, and exposed to the cold, burst by the expansion of the frozen fluid within them. Trees are frequently