Bui. 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- 

 asphaltic oil; bottom row contained no oil. Briquettes were immersed one year in a 10 per 

 cent solution of sodium sulphate. 



