Professor Dewar gave a very interesting lecture at the Royal
Institution a few days ago on liquefied oxygen and liquefied air, of which yesterday's Times contained a good re- port. He produced both liquefied oxygen and liquefied air, the oxygen in pints ; and even the liquefied air was handed round in claret-glasses. Liquid oxygen boils in air at —182° Centi- grade,—that is, 1820 of the Centigrade scale below zero. The liquid oxygen placed between the poles of Faraday's great magnet behaved like a metal, leaping up to the poles and clinging to them till it disappeared as gas. But liquid oxygen, though so strongly magnetic, is a very bad conductor of electricity. It is a non-conducting magnet. He showed, too, that so far as chemists can judge, there is probably no oxygen in the sun,—the oxygen of the earth's atmosphere accounting for all the oxygen lines in the solar spectrum. The boiling-point of liquid air is — 192° Centi- grade, or 10° lower than that of oxygen. It is not true, as had been supposed, that the oxygen in the air liquefies before the other elements in air ; on the contrary, the air liquefies as air, and is not resolved into its elements before liquefying. If this globe were cooled down to 200° below the zero of Centi- grade, it would be covered with a . sea of liquefied gas 35 ft. deep, of which about 7 ft. would be liquid oxygen.
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