Vol. 4 No. 2 



TORREYA 



February, 1904 LIBRARY 



Np.W YORK 



iiUTANICAL 



PHYSIOLOGICAL APPLIANCES — II. * 



By George E. Stone 



Apparatus for Collecting and Determining the Amount 

 OF Oxygen Given off by Aquatic Plants 



The appliance shown in Fig. 3 has been used in the writer's 

 laboratory, to some extent, for collecting and determining the 

 amount of oxygen given off by aquatic plants. It is based on 

 the same principles as that shown in Fig. i.f namely, either water 

 or mercury is employed to force the collected gas into the ab- 

 sorbent bulbs and return the same. 



In setting up the apparatus the graduated burette and funnel 

 are filled with water. As the gas is given off from the aquatic 

 plants it is directed from the funnel to the burette, where it is re- 

 tained, a corresponding amount of water being displaced through 

 the tube, ir, which should be below the water le\-el in the cj'lin- 

 der below. After a required amount of gas has been collected, 

 the pinch-cocks at d and c are closed, the funnel removed and 

 the gas is forced over into a phosphorus or pyrogallic acid and 

 potash bulb and then returned. The amount of oxygen absorbed 

 is then estimated. The remaining gas can also be tested for car- 

 bon dioxide and other gases if necessary. An appliance made 

 on this principle, provided with a smaller caliber and more finely 

 divided burette, has its advantages for closer work. 



* Continued from page 5. 

 fToRRKYA, 4 : 2. Ja 1904. 



[Vol. 4, No. I, of ToRREYA, comprising pages I-16, was issued January 27, 

 1904.] 



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