[Vol. 10 



222 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



* 



an oxidation period of 15 minutes for 100 mgms. of citric acid 

 and (4) a concentration of citric acid between 75 and 125 mgms 



TABLE I 



QUANTITATIVE DETERMINATIONS OP CITRIC ACID UNDER VARYING 



CONDITIONS 



Acid 



added, 



(mgms.) 



Vol- 

 ume, 



(cc.) 



Interval of 

 oxidation 

 (minutes) 



Min- 

 eral 

 acid, (cc.) 



Acid 



recovered 



(mgms.) 



Yield 

 (per cent) 



Remarks 









H3PO4* 









100 



50 



28 



5 



82.72 



82.7 





100 



75 



21 



5 



84.83 



84.8 





110.77 



100 





3 



H£04 



88.2 



79.6 





110 77 



50 





1 



102.9 



93.0 





110.77 



50 





10 



97.2 



88.0 





110.77 



50 





2 



101.5 



91.5 





110.77 



100 





2 



101.6 



91.6 





100 



75 



13 



5 



91.87 



91.8 



* 



100 



50 



11 



5 



93.63 



93.6 





100 



50 



14 



5 



93 . 98 



94.0 





125 



50 



15 



5 



118.45 



94.9 





125 



50 



15 



5 



118.9 



94.96 





75 



75 



8 



5 



65.82 



87.0 





75 



75 



12 



5 



67.58 



90.0 





75 



50 



10 



5 



65.64 



87.0 





75 



50 



10 



5 



65.64 



87.0 





75 



50 



12 



5 



67 . 23 



89.6 





75 



50 



14 



5 



67 . 58 



90.0 





83.07 







2 



74.1 



89.2 





55 . 38 







2 



49.67 



89.5 





110 77 



100 





2 



102.9 



92.7 



Oxalate added 



110.77 



100 





2 



101.9 



92.1 



KNO3, redis. 



110.77 



50 





2 



105.8 



95.5 



. 5 gm. dextrose 



* 85 per cent H 3 P0 4 

 t 5 N Il*SO« 



rRorosED Method 



APPARATUS 



Either the short -necked 500-cc. distilling flasks described by 



Willaman ('16) or the ordinary 



Kjeldahl flask is suitable 



for the distillation and for the receiver for the initial distillation. 

 A spiral condenser is not necessary but is desirable. The flask 



h. 



