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Bui. 607, U. S. Dep-t. of Agriculture 
Plate IX. 
Penetrance Specimens. 
Specimens arranged in order of treatment as given in Table 16. Group No. 1 treated with creosote. 
Time of treatment, 2 hours; pressure, 75 pounds per square inch; temperature, 180° F. Group 
No. 2 treated with 80 per cent creosote, 20 per cent tar. Time of treatment varied; temperature, 
180° F. Group No. 3 treated with 66| per cent creosote, 33§ per cent tar. Time of treatment varied; 
temperature, ISO F. Group No. 4 treated with 80 per cent creosote, 20 per cent tar. Pressure 
varied; temperature, 180° F. Group No. 5 treated with 66| per cent creosote, 33§ per cent tar. 
Pressure varied; temperature, 180° F. 
