430 



U. S. BUREAU OP FISHERIES 



Flexibility. — The flexibility of hemp Unes was measured at Fairport 

 for the first time, and the results of the tests are shown graphically in 

 Figure 15. The coal tar treatment (XX) caused the greatest amount 

 of stiffening, resulting in an immediate drop of about 70 per cent 

 in the number of oscillations of the pendulum. Next in increasing 

 order of flexibility come the lines treated with the copper oleate-coal 

 tar mixture (YY) and next the lines treated with the copper oleate 

 combination (SS, TT, UU," and VV) . Lines treated with quercitron 

 and ammoniacal copper sulphate (WW) showed the greatest im- 

 mediate increase in flexibility, but it will be remembered that these 

 same lines also showed the greatest immediate decrease in tensile 

 strength. 



12 3 4 5 6 



NUMBER OF MONTHS EXPOSED 



Fig. 14. — Tensile strength of hemp lines exposed at Fairport, Iowa 



Resistance to mechanical wear. — Tests upon the wearing quality of 

 manila hemp lines were also made on the series exposed at Fairport, 

 Iowa. Here, a^^ain, we find the same general tendencies as were 

 previously noted in the tests on the wearing quality of cotton lines — 

 that is, that the resistance to abrasion decreases directly as the 

 decrease in tensile strength. The results of these measurements are 

 shown graphically in Figure 16. The samples showing the greatest 

 resistance to wear were those treated with the copper oleates (SS, 

 TT, UU, and VV), coal tar (XX), and the copper oleate-coal tar 

 mixture (YY). The quercitron and ammoniacal copper sulphate 

 treatment (WW) caused a decided immediate decrease in wearing 

 quality. 



