240 



SOAPS AND PROTEINS 



be " killed " through the addition of various heavy metals. Saliva, 

 thus " poisoned " for weeks, will agair split starches to dextrose 

 when any of the light metal salts are added to it. But here again 

 interesting differences appear. While all the lighter metals act 

 in this fashion, excessive addition of such metals as potassium 

 will again kill the reaction. Apparently only when the enzyme 

 ^presumably a protein) has a medium grade of dispersion and 







FIGURE 113. 



hydration and not an excessive one with excessive solubility in 

 water will it best exhibit its starch-splitting properties. 1 



3. On the Nature and Relief of Heavy Metal Poisoning 



1 



It is perhaps fair to say that the present day treatment of heavy 

 metal poisoning is an attempt, in the main, to discover some 



1 This idea that optimal enzymatic activity is associated with a certain 

 degree of dispersion of the enzyme, independently arrived at by KEHOE, 

 was first discovered through other colloid-chemical methods by A. FODOR 

 (Fermentforschung, 4, 191, 209 (1920)). FODOR found that the enzymatic 

 activity (digestion of polypeptids) and ultramicroscopic picture of a phos- 

 phoprotein obtained from yeast was destroyed through the action of much 

 acid but that both could be restored through neutralization of the acid and 

 addition of KC1. 



