tul. 230, U. S. Dept. of Agriculture. 
Plate I. 
Briquettes Showing Repellent Action of Oil-Cement Concrete on Alkali 
Water. 
Top row contained 10 per cent of semiasphaltic oil; middle row contained 5 per cent of semi- 
asp haltic oil; bottom row contained no oil. Briquettes were immersed one year in a 10 per 
cent solution of sodium sulphate. 
