607, U. S. Dept. of Agriculture 
Plate I. 
A Thin Film of a Mixture of Equal Parts, by Volume, of Creosote and 
Normal By-Product Coke-Oven Tar No. 1 (Normal Amount of Free Car- 
bon in Tar, 6 Per Cent, by Weight). 
Magnification, about 400 diameters. 
