APPENDIX 



THE TECHNIQUE OF ELECTROCHEMICAL MEASUREMENTS 



IN PROTEIN SYSTEMS 



The carrying out of accurate electrochemical measurements in 

 solutions which contain proteins is attended by a number of diffi- 

 culties which result in part from the physical characteristics of 

 such solutions and in part from the instability of the proteins and 

 their tendency to undergo hydrolysis. The following is a descrip- 

 tion of the technique which I have found it best to employ when 

 obtaining such measurements in solutions of casein especially* but 

 also of ovomucoid and serum globulin. My experimental results 

 cited in Chaps. VIII to XI, inclusive, were obtained by these 

 methods; they are obviously applicable, with necessary or advisable 

 modifications, to aqueous solutions of the majority of proteins. f 



In the gas-chain determinations two platinized platinum elec- 

 trodes saturated with hydrogen are used, the one being dipped 

 in the solution of unknown hydrogen- or hydroxyl-concentration, 

 the other in a solution of known hydrogen- or hydroxyl-concentra- 

 tion, the latter being, as a rule, the solution of acid or base in which 

 the protein is dissolved and the former the solution of protein. 

 The electrodes which I employ are of a design due to my colleague, 



* Robertson, T. Brailsford, Journ. of Physical Chem., 14 (1910), p. 528. 

 t For the technique employed in determining H+ and OH' concentrations 

 and methods used in the computation of results, consult also 



Bovie, W. T., Journ. Medical Research 33 (1915), p. 295. 



Clark, F. W., Meyers, C. N., and Acree, S. F., Journ. Physical Chem. 20 



(1916), p. 241. 

 Clark, W. M., Journ. Biol. Chem. 23 (1915), p. 475. 

 Clark, W. M., Journ. Biol. Chem. 25 (1916), p. 479. 

 Clark, W. M., Journ. Bacteriology 2 (1917), pp. 1, 109, 191. 

 Hildebrand, J. H., Journ. Amer. Chem. Soc. 35 (1913), p. 847. 

 Lewis, G. N., Brighton, T. B., and Sebastian, R. L., Journ. Amer. Chem. Soc. 



39 (1917), p. 2245. 

 Michaelis, L., Die WasserstoflBonenkonzentration, Berlin (1914). 

 Schmidt, C. L. A., Univ. Calif. Publ. Physiol. 3 (1909), p. 101. 

 Sharp, L. T., and Hoagland, D. R., Journ. Agric. Research 7 (1916), p. 123. 

 Sorenseu, S. P. L., Ergeb. d. Physiol. 12 (1912), p. 393. 



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