432 



U. S. BUREAU OP FISHERIES 



4. Coal tar and the copper oleate-coal tar mixture preserved hemp 

 for five months. 



5. Copper oleate preserved hemp samples for three months. 



6. All linen samples were rotten in less than one month. 



7. Lines treated with copper oleate were not as flexible as those 

 used for previous tests. This was due to slight differences in the 

 manufacture of the oleate. 



8. It was again shown that as tensile strength decreases flexibility 

 increases. 



9. Resistance to mechanical wear decreases in direct proportion 

 to the decrease in tensile strength. 



30 



20 



10 



12 3 4 



NUMBER OF MONTHS EXPOSED 



Fig. 16.— Wearing quality of hemp lines exposed at Fairport, Iowa 



SERIES EXPOSED IN FRESH WATER OF THE POTOMAC RIVER AT 



WASHINGTON, D. C. 



Two identical series of cotton lines were exposed in the Potomac 

 River under the highway bridge at Washington, D. C. These 

 series were for the special purpose of determining how much the 

 life of twine could be prolonged b}^ removing it from the water every 

 30 days, washing, drymg, and treating it witli copper oleate. 



