CH. n] TIMIRIAZEFF'S EUDIOMETER. 45 



may be obtained with the Winkler-Hempel apparatus, 

 described in exp. 4, p. 6. 



The jar, J, fig. 3, containing leaves is filled with air 

 containing about 8 /o of C0 a : the exact proportion is of 

 no importance, but it must be accurately determined at 

 the beginning of the experiment. The bent tube t serves 

 to draw off a sample of the gas in the jar J, and as it is 

 drawn off, the water flows through the tube I from the 

 beaker o outside, into the second vessel inside i. The 

 tubes t and I are now clamped, and the apparatus exposed 

 to bright light for 4 or 5 hours when a fresh sample of gas 

 is drawn off and analysed. The water introduced absorbs 

 some of the CO 2 and causes an error, which however is not 

 so serious as to interfere w r ith the results for demonstra- 

 tion purposes. 



(52) Timiriazeff's Eudiometer 1 . 



For the analysis of gas given off from water plants 

 we use Timiriazeff's Micro-eudiometer arranged for the 

 analysis of larger quantities of gas, e.g. for 0'5 c.c. instead 

 of " a bubble no bigger than a pin's head." 



The apparatus (shown in fig. 10) consists of three parts 

 the eudiometer E, the pipette P, and the carrier G. 



The eudiometer is a tube of 5 mm. internal diameter 

 graduated in O'Ol c.c. : the upper end is covered by a 

 short (25 mm.) length of rubber tube through which 

 passes a glass rod R serving as a piston. The lower end 

 of E is enlarged into a small funnel F to facilitate the 

 entrance of the gas to be analysed. The carrier C consists 



1 Ann. Sc. Nat. S6rie vn. 1885, vol. n. p. 112. 



