Taylor and Wells. — Preservation of Nets and Lines. 61 



balance, and are accurate to the order of a milligram or two. By 

 experimentation, it was found advisable to weigh in the air-dried 

 or ordinary condition, which was the condition of lines in the 

 ordinary air conditions of the laboratory. If the samples were 

 dried to constant weight in an oven, they took up moisture so 

 rapidly during the weighing that it proved impossible to weigh 

 them without elaborate precautions. Where hundreds of samples 

 were prepared, these precautions were out of the question. Table 

 VIII gives the results of the determinations of weight, and Fig. 

 13 exhibits the results graphically. 



Table VIII. — Percentage of increase in weight of lines treated with 



VARIOUS preservatives. 



Symbol 



Miethod of treatment 



[Percentage of increase 

 in weight 



B 

 C 

 D 

 E 

 F 

 G 

 H 

 I 



J 



K 



L 



M 

 N 

 O 

 P 

 Q 



R 



S 

 X 



Copper oleate, 7% 



Copper oleate, 7%; 5% oil; 1-1,000 parts cresol 



Copper oleate, 11% 



Copper oleate, 11%; 2%oil 



Coal tar 



Pine tar 



Coal and pine tar, 50% each 



Bull's method 



Petroleum Product, No. 1 



Waterproofing material 



Dutch method 



Copper oleate, 7H% 



Copper oleate, 73^%; 5% oil; 1-1,000 cresol. . 



Copper oleate, 123^% 



Copper oleate, 12M%; 2% oil 



Copper paint I , 



Copper paint II 



Gilsonite 



Petroleum Product, No. 2 



11.9 

 18.0 

 20.6 

 22.9 

 68.5 

 53.9 

 48.0 

 9.8 

 48.6 

 17.8 

 20.2 

 10.2 

 15.1 

 15.4 

 18.6 

 65.5 

 127.0 

 46.0 

 35.3 



It will be seen that the preservatives which add least to the 

 weight are copper oleate and tanning methods, Bull's and the 

 Dutch methods. Tars add about 57 per cent to the weight of the 

 line and copper paint doubles it. 



The weight of the preservative is important in two ways : 

 (1) added weight increases the labor of handling and the strains 

 imposed on the line, and (2) added weight is an important con- 

 sideration where lines, nets, etc., are bought by weight, already 

 treated or preserved. 



(1) In such gear as large menhaden purse seines, where 

 the seine must be handled by hand by crews in the "purse boats," 



