Popular science monthly . y tempera-ture is a liquid. If we heatit to 212° F. it becomessteam, and if we cool it to32° 1. it becomes a is known as thekinetic theory of mattertells us that all moleculesare in perpetual \ibr£:licnat a tremendous \cIocityand are continually collid-ing with one another. Thisrate of molecular \ibrationproduces the temperatureof matter—the higher therate of motion the greaterthe temperature and viceversa. The molecules are in-cessanth gi\ing out theirenergy of motion and at thesame time are recei\ing thesemeclianical impulses fromotlicr ]iarticles of matt
Popular science monthly . y tempera-ture is a liquid. If we heatit to 212° F. it becomessteam, and if we cool it to32° 1. it becomes a is known as thekinetic theory of mattertells us that all moleculesare in perpetual \ibr£:licnat a tremendous \cIocityand are continually collid-ing with one another. Thisrate of molecular \ibrationproduces the temperatureof matter—the higher therate of motion the greaterthe temperature and viceversa. The molecules are in-cessanth gi\ing out theirenergy of motion and at thesame time are recei\ing thesemeclianical impulses fromotlicr ]iarticles of these simple facts i:imind, we may continue moreintelligently. Wlien we boil waterwe merely impart ener-gy in the form of heatto the molecules. Ifthe source of heat is intenseenough, the particles becomeI so wild in their vibration thatthe> come out of the range oftheir natural nnitual attrac-tion and pass olT as vapor. Ifthis vapor is cooled it againassiunes the liquid state, be-cause we ha\e taken energy. Popular Science Monthly 917 from the molecules and havecaused them to return totheir natural degree of vibra-tion. If we continue to coolthe liquid, we still furtherparalyze the motion of themolecules, until they becomeso crowded together that wehave a solid—ice. To Change a Gas into aLiquid—Cool It Now, then, in the light ofthe knowledge imparted inthe foregoing paragraphs, ifwe wish to change a gas to aliquid we must cool it. Thisis true. If sulphur dioxide(a gas obtained by burningsulphur) is cooled to a fewdegrees below zero, it con-denses into a liquid. As soonas the artificial means of The tin cup on theright was frozen byimmersion in liquidair, after which itwas easily broken cooling the gas iswithdrawn, it rap-idly assumes itsnatural state, asgas, by evapora-tion.* Now to getback to its naturalneeds a specific amount ofheat to make its moleculesvibrate at a definite rate,that which nature deter-mined. Where does it getthis heat. It abstracts itfro
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