[Vol. 6 



80 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



tions. In the work with phenylalanin, on the other hand, N/50 

 NaOH was used, since, as Sorensen ('07) noted, the compara- 

 tively insoluble barium salt formed shows a tendency to 

 adsorb the indicator. 



In this work, the solutions of definite hydrogen ion con- 

 centration with P H values between 8.0 and 9.6 were the borate 

 solutions described by Clark and Lubs ('17) ; beyond P H 9.6 

 they were the mixtures described by Sorensen ('09) or those 

 which vary by P H 0.2, and were made up from glycin, sodium 

 chloride, and sodium hydroxide solutions as accurately as 

 possible from the data given in the large chart which accom- 

 panies the French edition of the work. The quantities used 

 are given here, as this edition is less readily available. 



Solution 



No. cc. necessary to give Ph values indicated 







Ph values 



9.6 



27.0 

 73.0 



9.8 



32.0 

 68.0 



10.0 



37.0 

 63.0 



10.2 



41.0 

 59.0 



10.4 



44.0 

 56.0 



10.6 



46.0 

 54.0 



10.8 



47.5 

 52.5 



11.0 



48.8 

 51.2 



11.2 



49.5 

 50.5 



11.4 



50.4 

 49.6 



11.6 



51.2 

 48.8 



11.8 



52.2 

 47.8 



12.0 



NaOH 



54.0 



Glycin 



46.0 



The sodium hydroxide was N/10, the glycin solution was 7.505 

 gms. glycin and 5.850 gms. sodium chloride in 1000 cc. double 



distilled 



The resulting 9.6 solution was identical 



hydrogen ion concentration with the corresponding Lubs and 

 Clark borate solution. The sodium hydroxide solution was 

 practically carbonate-free and standardized against pure 

 oxalic acid, using thymolsulphonphthalein as an indicator. 

 The other chemicals were of the highest purity available in 

 commercial products and were further purified in some cases. 



Study 



the gas exchang 



the solution. — As stated 



the method of the study of oxygen absorbed was 



f McNair ('17). As 



solubility of carbon dioxide 



must also be considered and the technique of the Van Slykc 

 (17) carbon dioxide apparatus is involved, time has not per 

 mitted as extensive study of the gas exchange as I had hoped 

 Therefore this phase of the work is reserved for a later paper 



Discussion of Data 



Deamination. — All of the early work was directed toward 

 mere color changes and the question of the specificity of the 



