Tables of physical and chemical constants and some mathematical functions / by G.W.C. Kaye and T.H. Laby.

  • G. W. C. Kaye
Date:
[1941]
Catalogue details

Licence: Public Domain Mark

Credit: Tables of physical and chemical constants and some mathematical functions / by G.W.C. Kaye and T.H. Laby. Source: Wellcome Collection.

    66/200 (page 54)
    GAS THERMOMETRY GAS THERMOMETRY The thermodynamic scale of temperature is realized by the aid of the gas- thermometer, together with a knowledge of the equation of state of the gas used. In particular, the position of the zero of the Centigrade scale on the absolute scale is determined in this way. THERMODYNAMIC TEMPERATURE OF THE ICE-POINT Method. h2 N2 Air. C02 He Computer. O 0 O O O Joule-Thomson efiect 273-14 273-09 — 273-05 — Callendar, 1903 Extrapolation to zero pressure . 273-07 273-09 ■ • -- ■ Berthelot and Chap- puis, 1907 Joule-Thomson efiect 273-05 — 273-19 273-10 —• Berthelot, 1907 Extrapolation to zero pressure . *—■ -—- -—■ -—- 273-16 Reuse & Otto, 1930 -—- ■—- -—- — 273-16 Roebuck, 1936 --- --- — -- 273-14 Keesom and Tuyn, 1936 *- — *-* 273-17 Kinoshita and Oishi, 1937 273-16 to 273‘17 Beattie, 1937 Probable Mean 273T6°. PLATINUM THERMOMETRY TO REDUCE PT-SCALE TEMPS. (tpl) TO INTERNATIONAL SCALE TEMPS, (t) The interpolation formula for use with the platinum resistance thermometer for tempera¬ tures above o° C. is — R0(I + A^ + B72). For ease in computation, Callendar adopted the following method. The temperature is first calculated on the “ platinum scale ” (tpt) by assuming the linear relation Rpt — R0(i + «+) between temperature and resistance. The difference-coefficient, 8, is then introduced to correct to the parabolic relation by means of the formula t — tpt — 8.t(t — ioo)io-4. For temperatures between o° C. and — 190° C. the interpolation formula is R« = R0[i + At + Bt2 + C(t — ioo)2f3] for which the corre¬ sponding “ difference” formula becomes t— tpt + 8.i(t— ioo)io-4 + j8.t3(t— ioo)io~8. The three constants of the quadratic law are determined by calibration at the ice, steam and sulphur points. These values are also used in the low-temperature law, the additional constant being obtained by calibration at the boiling point of liquid oxygen. Pure platinum has a mean value of a over the range o° to ioo° C. of about 0-00392, while 8 lies between 1-49 and 1-495. Impure platinum has usually a high value of 8. Platinum thermometers are suitable for use at temperatures up to noo°C. See Ezer Griffiths’ “Methods of Measuring Temperature ” (Griffin). The use of the different formulae involves the use of a series of successive approximations. The use of the following table for a first approximation will shorten the work when high accuracy is required, and, above —40° C., will give sufficiently accurate results for most purposes without calculation. VALUES OF t FOR 3 = 150 Pt Temps. tpt• 0 20 40 60 80 100 120 140 160 180 t t t t t t t t t t -200° ■—■ -I7i°*5 -i53°*2 -134 °*7 -ii5°*9 -9 7°*o -77°* 84 -58°-59 -39°*i8 -i9°*65 0 0° 19-76 39*64 59*64 79-76 100 120-4 140-9 161-5 182-3 +200 203-1 224-2 245*4 266-7 288-1 309-8 33i*5 353*4 375*5 397-8 400 420-2 442-8 465*5 488-5 511-6 534*9 558-4 582-1 6o6-o 630-1 600 654*4 679-0 703-7 728-7 754*o 779*4 805-2 831-2 857*4 884-0 800 910-8 I 937*9 965*3 993-0 1021 1050 1078 1107 (1137) (1x67) 1000 (1197) (1228) (1259) (1290) (1323) (i355) *-- T CHANGE At IN THE INTERNATIONAL SCALE TEMP, (t) FOR A CHANGE OF -O’OI IN 8 t At t > t At t > r+. t At — 40°C. — o°-oo6 50° C. + 0°-002 800° C. 1 0 0 6 600° C. — o°-3o 900° C. —o°-7 -20 — 0-002 100 0 400 — 0-12 700 — 0-42 1000 — 0-9 0 0 200 — 0-02 500 — 0-20 800 — 0-56 1100 * — i-i