58 American Fisheries Society. 



more and less flexibility. These groups, the copper lines (M,. 

 N, O, P), the tanning methods (I, L), the copper paints (Q, R), 

 and those preservatives containing a heavy body, coal tar, pine 

 tar, mixed tars. Petroleum Product Nos. 1 and 2, and Gilsonite 

 (F, G, H, J, S, X), are grouped in Fig. 11, Here the lines pre- 

 served with copper oleate are far in the lead, showing upwards 

 of 60 oscillations. Next comes those lines preserved by querci- 

 tron, Bull's method and the Dutch method (I, L), with around 

 40 swings ; then the copper paints (O, R), with around 30 swings. 

 Finally, the tars, Petroleum Products, and Gilsonite, with around 

 20 swings. If we express the flexibility of tarred lines as 1, then 

 lines treated with copper paints have a flexibility of about 1^, 

 tanned lines about 2, and those treated with copper oleate about 3. 



DISCUSSION OF THE FLEXIBILITY TESTS. 



It has been seen in the results of breaking and wearing tests 

 that we have a choice of a number of excellent preserva- 

 tives, while others are definitely eliminated from consideration 

 by their failure to endure the tests. Those which fail to endure 

 the breaking and wearing tests are waterproofing materials. Pe- 

 troleum Products, Gilsonite, and Bull's method. Still in the run- 

 ning are the tars, copper paints, copper oleate, and the Dutch 

 method. Where flexibility is an important consideration, there 

 are now thrown out all the tars, the copper paints, leaving only 

 the Dutch method and the copper oleate as answering the re- 

 quirements of a first class preservative, which leaves the lines 

 soft, with the copper oleate far ahead of the Dutch method. For 

 gill nets, light seines and the like, copper oleate stands first in 

 the tests so far considered. 



Where stiffness is not objectionable, as in pound nets, traps, 

 etc., the copper paints are indicated. No doubt copper oleate 

 will answer splendidly also for this purpose, though the heavy 

 concentrations of copper desirable for this purpose have not 

 been tried. The copper paints have very much heavier concen- 

 trations of copper. Other considerations yet to be discussed 

 bring out further differences. 



SHRINKAGE OF COTTON LINES CAUSED BY THE APPLICATION OF 

 PRESERVATIVES. 



Some preservatives cause alteration of the length of lines; 

 all that have been so far studied either do not affect the length 



