PHARMACODYNAMICS OF SALTS AND DRUGS 99 



acid, the albumin combines with the hydrochloric acid and goes over 

 into the chloride. This at once dissociates the chlorine ion as a nega- 

 tive ion, and the albumin becomes the cation. It will, however, be 

 clear that, although in this case the albumin is mainly electropositive, 

 yet it is an acid, and the ionization of its hydrogen is not completely 

 suppressed, although it is reduced to a very small amount. This 

 means that here and there are albumin particles which are at one spot 

 electronegative, since they dissociate hydrogen, and in another spot 

 electropositive, since they dissociate chlorine. We have some am- 

 photer or twin ion colloids, in other words. The evidence of the 

 existence of such ions will be taken up on p. 104. 



I make this explanation at such length because it does not appear 

 to be clear to many that the albumin colloids owe their charges to 

 processes of ionization, just as any salts owe their charges to these 

 processes. Thus several writers have assumed that the charge was 

 owing to the salt introduced. The ion of the salt introduced which 

 moved fastest was supposed to bury itself in the colloid particle, and 

 thus give its charge to it. This hypothesis is quite unfounded and 

 undoubtedly erroneous. 



The proteids, therefore, in protoplasm exist as salts, and dissociate 

 sodium or other metallic ions, and chlorine and other anions, and the 

 colloids thus become charged. Some proteids here and there dis- 

 sociate both positive and negative ions. The colloids in protoplasm 

 are undoubtedly in the condition of a saturated solution, and we have 

 an equilibrium between dissociated and undissociated colloids, in 

 solution, and undissociated and dissociated precipitated colloids.* 

 It has been shown, furthermore, that the state of solution and the 

 fineness of subdivision of the colloidal particles depend on the number 

 of free electrical charges on their surfaces. The greater the number 

 of similar charges, the greater the solubility of the colloid. 



In determining the potential of the potential energy of the colloid, 

 we have, then, just the same factors to consider as in the salts, since the 

 colloids are salts. The potential of the energy content of the colloid 

 solution must be determined by the ionic potentials of the ions into 

 which it dissociates, for example, the potentials of sodium and albumin. 



*As a possible example of a dissociated insoluble colloid, fibrin which has been in acid may be men- 

 tioned. This fibrin dissociates hydrogen, but the hydrogen ion is unable to move away from the fibrin. 

 The condition is very similar to the double layer at the surface of an electrode. 



