46 



PLANT RESPIRATION 



designed to remove test portions of gas. A pinchcock is fitted to 

 the rubber tubing. To withdraw a suitable amount of gas the 

 level of mercury in the manometer tube is adjusted at any level 

 and the outer, vertical side of the entrance tube is then filled 

 with mercury. If the pinchcock is now closed the internal 

 atmosphere of the flask is left entirely separated from the 

 external air by glass and mercury, as is shown in Fig. 8. The 

 stopper is also faultlessly air-tight. The gas pipette of Kosty- 

 chev (Fig. 9) serves to draw the test 

 portions of gas from the container. By 

 the aid of the three-way stopcock r, 

 the bulb / can be connected with either 

 the tube g or the tube //. The single 



6 



Fig. 8. — Kostychev's flask. 



Fig. 9. — Kostychev's gas 

 pipette. 



stopcock / connects the bulb / with the pear-shaped bulb m. 

 The pipette is screwed to a stable wooden frame. 



With the aid of the pear-shaped bulb m, the bulb I and both 

 tubes g and h are filled with mercury. For this purpose the 

 pear-shaped bulb is elevated, the bulb / connected with the tube 

 g and the stopcock/ opened. As soon as the bulb and the whole 

 tube are filled to the further aperture with mercury and a drop 

 of mercury projects out, the stopcock r is so turned as to con- 

 nect the tube h with the bulb and to fill this tube with mercury, 

 after which the single stopcock / is closed. The curved end of 

 the tube g is then dipped in a thick-walled vessel of mercury and 

 the tube h is connected with the rubber tubing d of the Kosty- 

 chev flask just fitted out for the experiment. A certain amount 

 of mercury is drawn through it by lowering the pear-shaped 



