To show that the heat abstracted by the boiling of one liquid will freeze another, fill a tall narrow glass about half full of cold water (the colder the better), and place in it a thin glass tube containing some ether. Put them under the receiver of an air-pump. As you exhaust the air, the ether will begin to boil, until at length, by continuing the exhaustion, the water immediately surrounding the tube of ether will freeze, and a tolerably large piece of ice may thus be obtained. Ether evaporates so rapidly even under the pressure of the atmosphere, that a small animal, such as a mouse, may be actually frozen to death by constantly dropping ether upon it. If poured on the hand, it produces a degree of cold that soon becomes, to say the least, unpleasant. EXPERIMENT. Place a flat saucer containing about a pound of oil of vitriol under the receiver of the air-pump, and set in it a watch glass containing a little water, supported on a stand with _glass_ legs. Exhaust the receiver, when the water will evaporate, but without boiling; and the vapor being absorbed as it forms by the oil of vitriol, the vacuum is preserved, and the evaporation continues, until the vapor has abstracted so much caloric from the remainder of the water that it is all at once converted into ice. In most elementary works on chemistry may be found a long table of freezing mixtures, as they are called, some with and others without ice or snow. We have selected a few from each division. WITH ICE OR SNOW. {Snow or powdered ice 2 parts. {Powdered common salt 1 “ {Snow 5 “ {Powdered common salt 2 “ {Powdered sal ammoniac 1 “ {Snow 3 “ {Dilute sulphuric acid 2 “ {Snow 2 “ {Crystallized muriate of lime 3 “ WITHOUT SNOW OR ICE. {Sulphate of soda 3 parts. {Dilute nitric acid 2 “ {Nitrate of ammonia 1 “ {Water 1 “ {Phosphate of soda 2 “ {Dilute nitric acid 1 “ {Sulphate of soda 2 “ {Muriatic acid 1 “ The effects of most of these mixtures may be considerably increased by previously cooling the ingredients _separately_ in other freezing mixtures. In connection with this branch of science, and especially with chemistry, the youthful philosopher should practice the art of decanting air from one jar to another standing over water, beginning by passing it from a small to a larger jar, then with two of equal size; and when he can accomplish the transfer without permitting even one bubble to escape, he may essay the much more difficult task of transferring the air from a large to a smaller jar.