44 U. S, BUEEAU OF FISHEEIES. 



Table 20. — Tensile strength of linen lines exposed in fresh water at Put in Bay, Ohio. 



Symbol and treatment. 



Unex- 

 posed. 



Number of months 

 exposed. 



Tensile strength in pounds. 



T— Untreated line, control 



W — Dutch method 



BB — Petroleum product No. 2 



CC — Copper oleate, 15 per cent in gasoline 



(2) 

 (2) 



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



2 Line was disintegrated and gone. 



In this series the only preservative that shows any considerable 

 success is copper oleate, CC; all three of the other lines — that is, the 

 untreated line controls, T, and the samples treated by the Dutch 

 method, W, and with the petroleum product No. 2, designated BB — 

 failed to appear at all after one month of exposure. Of course, linen 

 ffill netting in practice would not be exposed to such conditions; 

 but all the lines received similar exposure, and copper oleate clearly 

 preserved better than any of the others. 



Just why copper oleate preserved better with linen line than with 

 cotton relatively to the other preservatives is not apparent. The 

 conditions at Put in Bay are worse for the lines, both cotton and 

 linen, than they are at either Woods Hole or Beaufort. At Beaufort 

 two of the linen samples — that is, the ones treated with copper 

 oleate and by the Dutch method — came through 120 days with 

 some strength left, and at Woods Hole the corresponding samples 

 were in good shape after 90 days, those preserved with copper 

 oleate still being equal in tensile strength to the original lines. Linen 

 is like cotton in showing more rapid deterioration in Lake Erie than 

 the Atlantic Ocean; but copper oleate preserved linen relatively 

 better than it did cotton. 



SUMMARY OF RESULTS OF PUT IN BAY E:?vPERIMENTS. 



1. The samples exposed at Put in Bay, Ohio, showed a general 

 tendency toward a more rapid deterioration than did similar lines 

 exposed in sea water. 



2. The exceptions to this statement were those lines treated with 

 the copper paints and tar-copper-oleate combinations, which sliowed 

 no deterioration of tensile strength in fresh or salt water in six 

 months, and the Dutch method, which preserved cotton lines better 

 in fresh water than it did in salt water. 



3. For cotton lines the copper paints and the combination of 

 copper oleate and tar gave splendid results, but both classes of the 

 preservatives stiffened the lines greatly. 



4. As between copper paints and the tar-copper-oleate combi- 

 nations, the preservation of tensile strength was equal, although in 

 wearing c[uality the tar-copper-oleate combinations greatly excelled. 



5. The Dutch method gave excellent results on cotton lines in this 

 series, preserving the saniples for the entire six months' period and 

 not causing excessive stiffness. 



