Bui. 607, U. S. Dept. of Agriculture. 



Plate III. 



A Thin Film of a Mixture of Equal Parts, by Volume, of Creosote and a 

 Normal Gas-House Tar No. 3 (Normal Amount of Free Carbon in Tar, 30 

 Per Cent, by Weight). 



Magnification, about 400 diameters. 



