Popular science monthly . Part of condenser in a laboratory refrigerating chamber is so cold that frost is formed. Yet liquidair would boil briskly if placed on the tubes At left: What remains of a largerubber cork after it has beenfrozen and struck with a hammer At left below: Twoscreweyes frozen into aI block of mercury sosolidly that they sus-tain the weight of two flatironssuspended from a great height formation of carbon dioxideappears on the mouth of thejet. Professor Dewar liquefiedh^drogen and helium in thelaboratory of the Royal So-ciety by a different methodfrom that of
Popular science monthly . Part of condenser in a laboratory refrigerating chamber is so cold that frost is formed. Yet liquidair would boil briskly if placed on the tubes At left: What remains of a largerubber cork after it has beenfrozen and struck with a hammer At left below: Twoscreweyes frozen into aI block of mercury sosolidly that they sus-tain the weight of two flatironssuspended from a great height formation of carbon dioxideappears on the mouth of thejet. Professor Dewar liquefiedh^drogen and helium in thelaboratory of the Royal So-ciety by a different methodfrom that of rapid evapora-tion. The principle appliedby him is based on the factthat a compressed gas al-lowed to expand freely great-ly lowers its own tempera-ture. Lord Kelvin madeknown this fact early in hiscareer, and it was commer-cially utilized by Linde, aGerman scientist, and byHampson, an English physi-cian. Both workers werelaboring independently ofeach *This is assuming that the gas isnot stored under pressure, whichprevents evaporation.
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1872
