APPLICATION OF ELECTRON DIFFRACTION 155 



Fig. 3 — Electron diffraction pattern produced by a layer of oriented crystals of an 

 aluminum soap, which had been formed as scum upon a water surface as a result of 

 the reaction of powdered aluminum, water and traces of organic acid present as an 

 impurity. 



Our experiments prove that aluminum hydrate is precipitated fairly 

 rapidly upon silica at pH values lying within a range in which lie also 

 the pH values of body fluids of men and of animals. Since in these 

 experiments aluminum hydrate is not formed upon silica at pH 4, it 

 seems highly probable that aluminum would not afford protection 

 from silicosis to a hypothetical animal with body fluids of pH 4. 



