FISH-NET PRESERVATIVES. 



43 



the copper oleate and tar combinations showed exceptional wearing 

 quahty. Running, as they do, very close to the copper paints in 

 flexibility and tensile strength, they excel copper paints so much in 

 wearing quality that their selection is already indicated for the heavier 

 types of gear where wear is a consideration. Copper oleate alone, i\A, 

 since it failed to preserve tensile strength, of course failed also in 

 wearing quality, because, as already pointed out, if tensile strength 

 is impaired the lines will make a poor showing in wearing quality- 

 whatever the results might otherwise be. We already know from 

 the other series that copper oleate is better in wearing quality than 

 any other preservative studied, and we can therefore with assurance 

 ascribe its failure here to failure to preserve the strength of the fibers. 

 The Dutch method, L, does not show a wearing quality that can 

 be called satisfactory, It makes 

 only 43 to 46 strokes on the 

 wearing machine against 399 for 

 fresh white line and 231 for lines 

 freshly treated with copper oleate 

 and tar. Nevertheless, the uni- 

 formity of results indicates good 

 preservation, as was seen in its 

 effect on tensile strength. The 

 Dutch method is therefore in 

 fresh water a good preservative 

 in general for cotton lines, though 

 it leaves much to be desired in 

 the particular factor of wearing 

 quality. The petroleum product 

 No. 2, designated X, is no better 

 in wearing quality than in other 

 particulars — it fails consistently, as far as tested, ana excels in no 

 quality. 



TESTS WITH LINEN LINES. 



!60 



:50 



;40 



£30 



^20 



10 



30 60 



DAYS EXPOSED 



90 



Fig. 28.— Teasile strength of linen lines exposed 

 in fresh water at Put in Bay, Ohio. 



MATERIALS TESTED. 



A series of linen lines identical in material, preservatives, and 

 preservative methods used with those at Woods Hole was exposed 

 at Put in Bay for a three months' period. The Hne was 10-ply linen 

 gill netting. The preservatives and preservative methods used were 

 copper oleate, 12| per cent concentration in gasohne and 5 per cent 

 oil, CC; the Dutch method, W; petroleum product No. 2, desig- 

 nated BB. 



TENSILE STREXGTH. 



The tensile strength of these lines before and after exposure is 

 given in Table 20, the same results appearing graphically in Figure 28. 



