Smithsonian Report, 1910. — Heaton. 



^Tapping- Hammer 

 Oxygen 



Plate 2. 



Hydrogen 



V 



2. "Boules" of Artificial Corundum. 



1. Principle of Verneuil's Appara- 

 tus for Production of Artificial 

 Corundum. 



3. Section of Natural Ruby, x 10. 



