PISH-NET PRESERVATIVES. 



37 



TENSILE STRENGTH. 



The results of determination of tensile strength before and after 

 exposure are shown in Table 15 and in Figure 24. 



Table 15. — Tensile strength of linen lines exposed in sea water at Woods Hole, Maes. 



Number of months 

 exposed. 



Symbol and treatment. 



Tensile strength in pounds. 



T— Not treated 



W— Dutch method 



RB —Petroleum product No. 2 



CC— Copper oleate, 15 per cent in gasoline. 



1 Average of 50 breaks; every other figure in this table is the average of 15 breaks. 



Although the Dutch method here shows some merit, copper oleate 

 easily leads, linen lines treated with it finishing the three months in 

 the water with the original strength unimpaired. The petroleum 

 product here, as elsewhere, failed to effect any noticeable preserva- 

 tion of the lines treated with it. 



SUMMARY OF RESUI^TS OF WOODS HOLE EXPERIMENTS. 



1. For cotton line seven preservatives and preservative methods 

 and untreated line as control were tested at Woods Hole, Mass., 

 being exposed from June 9 to De- 

 cember 9, 1922. The preserva- 

 tives and preservative methods 

 were two copper paints, two com- 

 binations of copper oleate and tar, 

 the Dutch method, copper oleate, 

 and petroleum product No. 2. 



2. For linen lines three pre- 

 servatives and preservative 

 methods and the untreated line as 

 control were tested, being exposed 

 from June 9 to September 9, 1922. 

 The preservatives and preservative 

 methods were Dutch method, pe- 

 troleum product No. 2, and copper 

 oleate. 



3. Exposure in the water at 



Woods Hole had a much less severe effect on lines, treated or not, 

 than at Beaufort. 



4. In combinations of copper oleate and tar it made little differ- 

 ence whether the two were mixed and applied or applied separately. 



5. These combinations of copper and tar effected about the same 

 degree of preservation of tensile strength and stiffened the lines to 

 about the same degree as the copper paints but were far superior to 

 copper paints in mechanical wearing quality. 



60 



:50 



\A0 



30 



S20 



10 



30 60 90 



DAYS EXPOSED 



Fig. 24.— Tensile strength of linen lines exposed 

 in sea water at Woods Hole, Mass. 



