66 American Fisheries Society. 



tives have their own, and very often decided, opinions on the 

 subject, the colors produced are given here: 



Table XI. — Color imparted to lines by preservatives. 



Preservative 



Color of treated line 



Copper oleate . 



Tar 



Copper paint 



Petroleum Products, Nos. 1 and 2 . 1 Black. 



Gilsonite Black. 



Tanning extracts: 



Dutch method Brown. 



Bull's method Dark brown 



Apple green, sky blue, or strong brilliant 

 green, depending on concentration of 

 preservative. 



Dark brown or black. 



Dark coppery red. 



GENERAL DISCUSSION AND SUMMARY. 



There have been presented the results of investigations 

 which establish certain facts regarding the characteristics of sev- 

 eral important or well known net preservatives. These results 

 show that some materials that are used have little or no value 

 as preservatives, others are good in some respects, while still 

 others excel in most or all respects. 



The following materials for, or methods of, preserving may- 

 be eliminated, on the basis of these results : quercitron mordanted 

 with potassium bichromate (Bull's method), waterproofing ma- 

 terial, Gilsonite, and the Petroleum Products Nos. 1 and 2. 



We may classify the points of usefulness of the remaining 

 preservatives on the basis of the service the treated gear must 

 perform : 



(1) Where the gear is to remain immersed for a long time, 

 and where added weight and greatly increased stiffness are per- 

 missible, the copper paints excel. They protect tensile strength, 

 and prevent fouling, but they resist mechanical abrasion rather 

 poorly. The tars are good preservatives, but foul heavily with 

 hydroids and barnacles. Both are slow in drying. 



(2) Where softness, flexibility, and lightness are necessary, 

 as in gill nets, light seines, etc., the choice is between copper 

 oleate and the Dutch method with copper oleate leading in every 

 particular — preserving quality, wearing quality, flexibility, light 

 weight, insignificant shrinkage, and particularly ease and rapidity 

 of application. 



