. A treatise on pharmacy for students and pharmacists. rcomesthe pressure of the surround-ing atmosphere, or, in otherwords, beyond which theliquid cannot contiuue as aliquid without increased pres-sure. JSTormal atmosphericpressure, 15 pounds to thesquare inch, which is equalto the pressure of a columnof mercury 760 Mm. ( +inches) in height, is alwaysassumed when referring to theboiling-point of a liquid, forany modification of the formerwill change the latter; thuswater, which ordinarily boilsat 100° C. (212° F.), hasbeen known to boil at 84° C.(°F.) on Mont Blanc, inSwitzerland, a
. A treatise on pharmacy for students and pharmacists. rcomesthe pressure of the surround-ing atmosphere, or, in otherwords, beyond which theliquid cannot contiuue as aliquid without increased pres-sure. JSTormal atmosphericpressure, 15 pounds to thesquare inch, which is equalto the pressure of a columnof mercury 760 Mm. ( +inches) in height, is alwaysassumed when referring to theboiling-point of a liquid, forany modification of the formerwill change the latter; thuswater, which ordinarily boilsat 100° C. (212° F.), hasbeen known to boil at 84° C.(°F.) on Mont Blanc, inSwitzerland, and even at 35°C. (95° F.) in a vacuum ap-paratus ; while, under greatlyincreased pressure, as in Pa-pins digester, it has beenheated to 160° C. (320° F.)without boiling. There existsalso a great variability inthe boiling-points of differentliquids under normal condi-tions ; for, while official etherboils at about 37° C. (°F.), chloroform requires a tem-perature of ° C. (°F.), alcohol 78° C. (°and mercury about 357° Davenports constant water-bath. F.), glycerin 165° C. (329° F.)(° F.). The simplest method for determining the boiling-point of a liquidis to introduce some of it into a flask provided with a lateral tube inthe neck and a thermometer passing through the cork, as shown inFig. 69, or into an ordinary Florence flask provided with a doubly- HEAT. 83 perforated cork, through one orifice of which a thermometer is insertedand through the other a bent glass tube, as represented iu Fig. inflammable or uoxious vapors are likely to be evolved, the tubefrom either flask may be connected with a condenser. It is importantthat the thermometer should not be immersed in the liquid, but onlyintroduced iuto the flask so far that the bulb may be enveloped by
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Keywords: ., bookcentury1800, bookdecade189, booksubjectpharmacy, bookyear1895
