FISH-NET PRESERVATIVES. . 7 



precipitate first formed near the surface of the line prevents further 

 penetration of the reagents, and (2) the precipitate is in the form of 

 irregular particles adhering to the fibers, not enveloping them in a 

 continuous film. It was found that a uniform deposit could be 

 produced and thorough penetration effected if the copper soap were 

 dissolved in a suitable solvent and so applied. Benzol, gasoline, 

 carbon tetrachloride, turpentine, oils, etc., dissolve copper oleate, but 

 not stearate. Accordingly, attention was from this time confined to 

 copper oleate dissolved in benzol, gasoline, kerosene, etc., and in the 

 many experiments with samples of lines preserved copper oleate was 

 included in a variety of concentrations and combinations to determine 

 its value absolutely and in comparison with other preservatives. 



Before further experiments were begun, however, it was necessary 

 to solve certain problems connected with the application of copper 

 oleate solutions. It was found that when benzol is used as a solvent 

 the solution in the line creeps to the surface during the evaporation 

 of benzol, so that on the dried line almost all of the copper oleate is on 

 the outside. It was found that a small quantity of mineral oil added 

 to the benzol solution remains and prevents the oleate from creeping. 

 With gasoline the difficulty was scarcely so great, yet it seems wise 

 to add the oil, by which means a perfectly uniform deposit is secured 

 throughout the line. 



EXPERIMENTAL EXPOSURE AND TESTING OF LINES. 



Four series of experiments were undertaken with a view of deter- 

 mining the effects of the preservatives. Different geographical 

 regions were chosen to determine differences that might arise from 

 that cause; and from time to time new tests were carried out as the 

 need for them appeared and as soon as the technique of applying 

 them could be worked out. These tests will be described as they 

 arise in connection with the experiments. No. 24 cable-laid, hard- 

 finish cotton line was used uniformly throughout for cotton line ; for 

 linen line 10-ply salmon gill netting was used. The results are 

 therefore comparable. 



NOTATION OF SAMPLES. 



In the following key all samples designated by the same letter of 

 the alphabet are always treated with the same preservatives in the 

 same way. In all the results recorded herein the symbols and 

 identifying numbers refer to this key. 



Key to symbols for preservatives studied. 

 COTTON LINES. 



A White line — untreated — No. 24 medium laid cotton line used as a control. 



B Copper oleate — 7 per cent concentration in gasoline. Lines were dipped into 



this solution and allowed to become thoroughly saturated. This requires 



two or three minutes. The lines were then removed and spread out to dry 



(not piled in a heap). 

 C Copper oleate — 7 per cent concentration in gasoline and containing 5 cc. of 



mineral oil to every 95 cc. of solution and 1-1000 parts of cresol. Applied 



same as B. 



D Copper oleate — 11 per cent concentration in gasoline. Applied same as B. 



E Copper oleate — 11 per cent concentration in gasoline and containing 2 cc. of 



mineral oil for every 95 cc. of solution. Applied same as B. 



