8 TJ. S. BUREAU OF FISHERIES, 



F Equal weights of heaw coal tar (sp. gr. about 1.25) and benzol were mixed. 



The benzol thinned the tar sufficiently, so that no heating was necessary. 

 The lines were then dipped into this tar-benzol solution, soaked for 5 or 10 

 minutes, and then wound out on a reel to dry. As the lines were drawn 

 out of the tar they were drawn between the fingers in order to remove the 

 excess tar adhering to the lines. This may also be accomplished by using 

 a wringer. 



G Equal weights of pine tar (sp. gr. 1.18) and benzol were mixed, the benzol 



serving as a thinner, and thus eliminating the iise of heat. Applied same 

 asF. 



H Coal tar 25 per cent, pine tar 25 per cent, and benzol 50 per cent were mixed 



and applied same as F. 



I Quercitron and potassium bichromate. The lines were steeped in a hot 



solution of quercitron, 1 pound to 2 gallons of water, until the solution was 

 cold, dried, again steeped in the same way and again dried. They were 

 then immersed for a few minutes in a solution of potassium bichromate 3J 

 pounds to 150 gallons of water. This method was tried for the purpose of 

 comparison with the Dutch method in which tanning extract and copper 

 are used together. 



J Petroleum product No. 1. This is a product made and sold by a western oil- 

 refining company as a preserA^ative for fish nets. It is a heavy, black 

 liquid, closely resembling tar and is applied in the same way as tar; that is, 

 by dipping once in the cold liquid and then winding on a reel to dry. The 

 product is ready for use as purchased from the manufacturer. 



K Proprietary waterproofing material. All lines used in experiments with 



this material were treated at the factory of the concern making the material. 

 The material is a thin, black liquid of specific gravity about 0.850 and is 

 applied by dipping the line into the solution. No heating is necessary. 



L Dutch method. The lines were steeped in a hot solution of quercitron, 1 



pound to 2 gallons of water, until the solution was cold, dried, again steeped 

 in the same way, and again dried. They were then immersed for a few 

 minutes in an ammoniacal solution of copper sulphate, containing 1 pound 

 of copper sulphate and 3 pounds of 25 per cent liquid ammonia for every 

 12^ gallons of water. For a full description of this method see Olie (1918). 



M Copper oleate — 7^ per cent concentration in gasoline. Applied same as B. 



N Copper oleate — 12^ per cent concentration in gasoline with 5 cc. of mineral 



oil for every 95 cc. of the copper oleate solution, and 1-1000 parts of cresol. 

 Applied same as B. 



O Copper oleate — 12^ per cent concentration in gasoline. There was no mineral 



oil added to this. It was run for the purpose of comparison with those 

 combinations of copper oleate solution with oil. Applied same as B. 



P Copper oleate— 12^ per cent concentration in gasoline with 5 cc. of mineral 



oil to every 95 cc. of copper oleate solution. Applied same as B. 



Q Copper paint No. 1. This is a red copper paint similar to that used on ships' 



bottoms. The principal ingredient is copper oxide suspended in some 

 vehicle, such as thin coal tar. The paint was mixed with an equal volume 

 of creosote oil and the line dipped into this solution. The twine was then 

 wound out on a reel. It is preferably used immediately after such treat- 

 ment, but may be allowed to dry before putting in water. 



R Copper paint No. 2. This is another red copper paint, similar to Q, but con- 

 taining more copper. This is applied without any additional thinning, 

 but otherwise the same as Q. The preservative may be allowed to dry or 

 used immediately. The twine was left much stiffer than when treated 

 with copper paint No. 1, and the increase in weight was much greater. 

 More copper was deposited in the line than in the case of Q. 



S Gilsonite. This is an asphalt product sold by a western company under a 



proprietary name as a fish-net preservative. It is a thin, black liquid 

 having a specific gravity of about 0.870. The product is sold ready for use 

 and is applied by allowing the line to soak in the liquid for about 20 minutes 

 and then winding out on a reel and allowing to dry. 



X Petroleum product No. 2. This product is sold by the same concern as was 



petroleum product No. 1(J). The No. 2 is a black liquid, thinner than No. 

 1, and intended for use on gill nets and other light gear that must be left 

 flexible. Applied same as J. 



Y This preservative is a mixture of 50 per cent heavy coal tar (road tar), 35 



per cent benzol, and 15 per cent copper oleate (each by weight). Applied 

 same as F. 



