22 



COLLOIDS IN BIOLOGY AND MEDICINE 



If it is unnecessary to determine constants, the direct graphic- 

 representation of results is the simplest method. The concentra- 

 tion in water (the dispersing substance) is made the abscissa. The 

 ordinate is the adsorbed amount of the dispersed phase. (This is 

 the difference between the entire quantity of the substance dis- 

 solved and what remains in solution.) The points of intersection 

 are points of the curve experimentally derived. The lines show us 

 at a glance (as is seen in Fig. 2), in simple cases, whether the dis- 



C (concentration) in the water 

 FIG. 2. 



tribution and curve is one of chemical combination, solution or 

 adsorption. 



The heavy continuous line ( ) is the graphic representation of 



a chemical reaction: 3 mols CaCOs are suspended in water and 

 H 2 SO4 is added. It is at once seen from the diagram that 3 mols 

 H 2 S04 are bound, i.e., there is no free H 2 SO4 in the water, but on the 

 addition of more H 2 SO4 the dispersed phase can take up no more 

 acid, so that the acid remains in the dispersing medium. 



The broken line ( ) is the graphic representation of the dis- 

 tribution of a substance between two solvents. The dot and dash 

 line (- -) is an adsorption curve. For the graphic representation of 

 such adsorption phenomena the above equation is solved by log- 

 arithms; and we obtain 



- -logc. 



