34 



U. S. BUREAU or FISHERIES. 



creosote, the natural toxic principle of fresh tar, escapes during a 

 short term of exposure. 



It may further be noticed that the water at Woods Hole is not so 

 severe in its effect on lines as that at Beaufort. The strength of the 

 lines after the second month at Beaufort is similar to that of the 

 Woods Hole lines after the fourth month. 



FLEXIBILITY. 



The samples used in this test were tested for flexibility by the 

 pendulum method already described. The results of these tests are 

 given in Table 13 and are shown graphically in Figure 22. 



70 



60 



2 50 



o 40 



t 30 



20 



Fig. 22.— Flexibility of cotton lines exposed in sea water at Woods Hole, Mass. 

 Table 13. — Flexihility of cotton lines exposed at Woods Hole, Mass. 



Symbol and treatment. 



TJnex- 



Number of months exposed. 



Number of oscUlations. 



A — Untreated white line control , 



L — Dutch method 



Q— Copper paint No. 1 



R— Copper paint No. 2 



X — Petroleum product No. 2 



Y— Copper oleato 15 per cent, benzol 35 per cent, coal tar 50 



per cent 



Z — Copper oleate followed by coal tar 



AA — Copper oleate 15 per cent in gasoline 



41.3 

 44.9 

 31.1 

 29.4 

 34.3 



27.0 

 35.3 

 43.1 



(') 



59.3 

 41.5 

 35.6 

 (?) 



58.6 

 40.3 

 70.0 



1 Each figure in this table is the average of 100 tests. 

 'Line was disintegrated and gone. 



The general trend of the lines is at first toward a slight stiffening 

 and later toward an increasing flexibility. The line AA, preserved 

 with copper oleate, easily leads all the lines in flexibility, being more 



