214 SOAPS AND PROTEINS 



both. It should only be noted that the concentrations marked 

 on the labels of Figs. 102 and 103 are those of the acid as added. 

 The final concentrations are given in Table LXVII. 



Such experimental findings as have just been described are 

 more commonly listed, as by the physiological chemists, as experi- 

 ments on the " solubility " of proteins; or by the physical and 

 colloid-chemists as studies on the effects of alkalies and acids upon 

 such " solubility " or some other of the general chemical or colloid- 

 chemical properties of the systems as a whole (as their viscosity, 

 their electrical conductivity, their content of hydrogen and 

 hydroxyl " ions," etc.). To understand these systems properly 

 it is obviously necessary to recognize and carry in mind the effects 

 of (a) the quantitative relationships of the water content of the 

 systems to the remaining material in them, (6) the chemical con- 

 versions of " neutral " compounds into basic or acidic derivatives, 

 (c) the alterations in solubility and hydration capacity accompany- 

 ing such conversion, (d) the types of systems produced (whether 

 all hydrated colloid, all solution in water or subdivisions of the 

 one in the other) and finally (e) the changes in viscosity incident 

 to " emulsification " or " suspension " of any of the original 

 unchanged " globulin " in such hydrated derivatives as may be 

 produced. How inadequate for the understanding of the colloid- 

 chemical behavior of such systems are the overplayed " stoichio- 

 metrical," " chemical," " electrical," " hydrogen and hydroxyl 

 ion " notions, usually called upon to explain in some exclusive 

 fashion all the changes observed, must be self-evident. 



Stoichiometrical views cover only those parts of the whole 

 problem which have to do with the quantities produced of dif- 

 ferently hydratable or soluble compounds; " chemical " notions 

 are no more adequate for the explanation of the problem than 

 they are, at present, for the understanding of the whole problem 

 of solution; electrical and ionic notions are hardly of service when 

 it is remembered that the most stabile of these hydrated colloid 

 systems are such as are composed of chemically produced, really 

 neutral compounds of protein with base or add, provided only that 

 not more water is present in the system than can be absorbed by 

 the hydration capacities of the protein derivatives. Yet these 

 colloid systems contain no quantities of either hydrogen or hydroxyl 

 ions measurable by ordinary laboratory means. The measurable 

 hydrogen and hydroxyl ion contents of different protein/ water systems 



