. Smithsonian miscellaneous collections. ) the sensitivity of the present appara-tus is approximately 1 part in 2 million by volume. The uncertaintyof a determination, arising chiefly from the error in measuring thegalvanometer deflection and from slight fluctuations of the filamentcurrent, is 1 to 2 parts per thousand; with the present apparatus this Smithsonian Miscellaneous Collections, Vol. 104, No. 4 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 corresponds to about 8 cmm. C02 at a concentration equal to normalair and to about 2 cmm. C02 at zero C02 concentration. Control and measureme
. Smithsonian miscellaneous collections. ) the sensitivity of the present appara-tus is approximately 1 part in 2 million by volume. The uncertaintyof a determination, arising chiefly from the error in measuring thegalvanometer deflection and from slight fluctuations of the filamentcurrent, is 1 to 2 parts per thousand; with the present apparatus this Smithsonian Miscellaneous Collections, Vol. 104, No. 4 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 corresponds to about 8 cmm. C02 at a concentration equal to normalair and to about 2 cmm. C02 at zero C02 concentration. Control and measurement of air temperature.—Unless otherwisespecified, the air temperature was maintained at approximately ° temperature of the air in the plant chamber was measured C. by means of a thermocouple with one junction (shielded bya housing of bright metal foil) situated adjacent to the leaves andthe other junction in a bath of ice and water. Readings were takenat 10-minute intervals during the respiration runs. Fig. —Optical system employed in spectrographic method for determination of carbon dioxide. Control of relative humidity.—The relative humidity of the circu-lating air was controlled by saturating it with water vapor at onetemperature and then warming it to another. These temperaturescould be adjusted to give any desired relative humidity and air tem-perature. It should be mentioned, however, that no means of actuallymeasuring the relative humidity of the air was provided, so that theremay exist some uncertainty as to whether the calculated humiditywas actually obtained. Experiments designed to study the influenceof humidity on respiration indicated that, under the conditions pre-vailing, this factor was of minor significance. NO. 4 LIGHT AND RESPIRATION WEINTRAUB AND JOHNSTON ^^ ^ ^itJii J^ ? • Sfis1 =-f?-F^^B-?jTIT«^ jj^TT^+T ^ X rX-c ^X_|_±^ Tt+t. -??? 1 : , L XX -J P^ l!^ s.*7^ x^xJxh± _l _+_ 1 V 1 1 X4^ i -: ! ; ! ! 1 ? ,
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Keywords: ., bookauthorsm, bookcentury1800, bookdecade1860, booksubjectscience
