FISH-NET PRESERVATIVES. 



27 



should be noted that the tarry preservatives, or others having a 

 protective body, do have the property attributed to them of protect- 

 ing against chafing or wearing. 



Upon exposure, however, the relative wearing abilities rapidly 

 change. The untreated line, A, and lines treated by the petroleum 

 products J and X, gilsonite, S, and quercitron and potassium bicliro- 

 mate, I, all rapidly lose wearing quality so that in two months it is 

 practically zero. Lines treated with the copper paints, Q and R, 

 never have much wearing ability, even when freshly treated. Yet, 



360 

 340 

 320 

 300 

 280 

 260 

 240 

 220 

 200 

 180 



reo 



\r> 



\U 



ol40 

 ec 



^100 



:e 

 :o 



=^80 

 60 

 40 

 20 



m 



£f2 



12 3 4 



NUMBER OFMOrfTHS EXPOSED 



Fig. 15. — Wearing quality of cotton lines exposedi n sea water at Beaufort, N. C, 



grouped. 



because decomposition of the line is so well prevented and tensile 

 strength so well preserved, such wearing quality as tbey have persists 

 well through the full six months. The tarred lines do fairly well but 

 suffer a steady decline in wearing quality. Lines preserved with 

 copper oleate lead all others after the first month. This material is 

 waxy or soapy and seems to possess physical properties that enable 

 a line treated by it to rub without giving up its hbers. The harsh- 

 ness of copper paint and of the tanning extracts also is easily palpable 

 and shows up clearly in the results. The conclusions from this test 

 are plainly that (1) all preservatives studied cause an immediate 



