. Preventive medicine and hygiene. an Orsat tube con-taining a strong solution (20 per cent.) of potash, which absorbs theCO2. The air is then returned to the gas buret and remeasured forloss in volume. Great care must, of course, be exercised that the pres-sure and temperature are precisely the same before and after absorp-tion. The gas buret A, Fig. 82 is first filled with mercury by raisingthe reservoir E. The sample to be analyzed is then drawn into A by low-ering E. There must always be a drop of water on the surface of themercury and also in the compensating cylinder C. In this way theai
. Preventive medicine and hygiene. an Orsat tube con-taining a strong solution (20 per cent.) of potash, which absorbs theCO2. The air is then returned to the gas buret and remeasured forloss in volume. Great care must, of course, be exercised that the pres-sure and temperature are precisely the same before and after absorp-tion. The gas buret A, Fig. 82 is first filled with mercury by raisingthe reservoir E. The sample to be analyzed is then drawn into A by low-ering E. There must always be a drop of water on the surface of themercury and also in the compensating cylinder C. In this way theair sample is kept saturated with moisture. In reading the volumesthe meniscus of the mercury is each time so adjusted that the pressurein A is exactly the same as the pressure of the air in the compensating 676 COMPOSITION OF THE AIR cylinder C. This is accomplished through a differential manometercontaining a drop of colored liquid (petroleum, in which azobenzol isdissolved). This manometer is connected by capillary glass tubes on. Fig. S2—Petterson-Palmquist Apparatus. one side with A and on the other side with C. After the gas pipet Ais filled with the sample of air to be tested, close the stopcocks D, F, C,and G and adjust the level of the mercury in A, so that the drop of liquid CARBON DIOXID 677 in the manometer stands at zero on the scale. This adjustment is accom-plished througli the set screw E. In this way the air in A may alwaysbe brought to the same pressure as that prevailing in the compensatorC. Since the air in both compensator and pipet is, from the begin-ning of the experiment, separated from the external atmosphere by clos-ing the stopcocks f, g, and c, variations in the external atmospherehave no effect. The temperature is regulated by filling the jar withwater and keeping it agitated, preferably with bubbles of compressedair. Each analysis consists of three operations: (1) The air is drawn in from the outside and is measured, thelevel of the mercury in the
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Keywords: ., bookauthorwh, bookcentury1900, bookdecade1910, booksubjecthygiene
