4 U. S. BUREAU OF FISHERIES. 



under a trade name), and two combinations of copper oleate and 

 coal tar. 



2. The textiles tested were No. 24 cable-laid, hard-finish twine 

 cotton andlO-ply linen thread. 



3. The factors determined were tensile strength, flexibility, wearing 

 quality, increase in weight, shrinkage, resistance to fouling by marine 



frowths, color imparted, and in some cases liability to spontaneous 

 eating. 



4. For determining flexibility and wearing quality machines were 

 devised and made. The construction and operation of these ma- 

 chines are described. 



5. Series of lines treated with various preservatives were exposed 

 to weather conditions in the air, in Atlantic Ocean water at three 

 places, and in fresh water at one place. 



6. In the series exposed to weather conditions, the deterioration 

 was comparatively slight. Those preservatives with a heavy body, 

 such as the tars and gilsonite, preserved better than did those without 

 heavy body. 



7. In the salt water, if preservation of tensile strength only is con- 

 sidered, those samples that contained copper in some form were best 

 preserved. 



8. Tar was a fairly good preservative in salt water for about two 

 months, after which time lines treated by it began to lose strength. 

 Coal tar and pine tar were similar in effect, but coal tar was slightly 

 better. 



9. Tar, either coal or pine, caused a great increase in stiffness and 

 weight, both of which increases were quantitatively measured. 

 Tar failed to protect nets against fouling by growths of hydroids and 

 barnacles. 



10. Tanning by quercitron followed by a treatment with potassium 

 bichromate, without copper, was a poor preservative. Lines treated 

 by this method showed little superiority to untreated lines. 



11. Tanning by the Dutch method (quercitron followed by am- 

 moniacal copper sulphate, or bluestone, solution) was much better 

 than quercitron and potassium bichromate. It deposited some cop- 

 per in the line, preserved fairly well, and increased weight and stiffness 

 only slightly. It was troublesome to apply, caused considerable 

 shrinkage oi the hne, and was not so good generally as preservatives 

 that deposit more copper in the line. On cotton lines in fresh water 

 it was a good preservative. 



12. The proprietary petroleum products and a proprietary gilsonite 

 that were studied showed little value as net preservatives. They 

 increased the weight and stifi'ness of the line without causing any 

 noticeable preservation. They showed no favorable effect on tensile 

 strength, wearing quality, or resistance to fouhng. 



13. Copper pamt, of which two commercial brands were studied, 

 gave excellent preservation of tensile strength and resisted to a high 

 degree fouling by marine growths; but it excessively increased stiff- 

 ness and weight of lines to which it was applied, and because of its 

 harshness greatly diminished the resistance of the lines to abrasion 

 or wear. 



14. Copper oleate, here tested for the first time and now proposed 

 as a net preservative, showed many valuable characteristics. Dis- 

 solved in gasoline and applied it penetrated instantly and dried on 



