The Americana; a universal reference library, comprising the arts and sciences, literature, history, biography, geography, commerce, etc., of the world . re becomes 212 F., 100°C. At pressures employed in the modern steam-engine, 6 to 10 and 15 atmospheres, the tempera-tures rise to from 320° to 356° and 390° F., 160°to 180° and 199° C. Meantime, the volumes ofthe vapor decrease, relatively to unit volume ofwater of maximum density, from 1646 at one at-mosphere to 300 at 6, to 188 at 10, and to 125at 15 atmospheres. This change demands theexpenditure of energy sufficient to increase therate of
The Americana; a universal reference library, comprising the arts and sciences, literature, history, biography, geography, commerce, etc., of the world . re becomes 212 F., 100°C. At pressures employed in the modern steam-engine, 6 to 10 and 15 atmospheres, the tempera-tures rise to from 320° to 356° and 390° F., 160°to 180° and 199° C. Meantime, the volumes ofthe vapor decrease, relatively to unit volume ofwater of maximum density, from 1646 at one at-mosphere to 300 at 6, to 188 at 10, and to 125at 15 atmospheres. This change demands theexpenditure of energy sufficient to increase therate of molecular vibration, storing the sensibleheat producing the change of temperature andmeasured by the product of the range of tem-perature into the specific heat of the fluid, andan amount of energy measured by the product ofthe change of volume into the external and in-ternal resistances to that expansion, measuringthe externa! and internal, so-called latentheats. Sensible and total heats are usuallymeasured from the freezing point. .-\t ten at-mospheres, for example, the heat measured, re-spectively, as sensible, as internal latent and as. Newcomens Engine (1705).— B, boiler; a, steam-cylinder; i ;-, piston and rod; K, pump rod. external latent and as total latent heats, havethe relation, very nearly, of one to two and ahalf, to one fourth, to three and three fourths. In the production of steam from water attemperatures below the boiling point, threestages may be observed. In the first, the waterrises in temperature without sensible change ofvolume, and substantially all of the heat suppliedremains in the form of sensible heat; in thesecond, the process is one of conversion of thewater at the boiling point under the observedmaximum pressure, from the liquid to the vapor-ous state at unchanging temperature, and allheat supplied is converted into the mechanicalvvork of expanding the fluid against internal andexternal resistances from the volume of theliquid to that of
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