FISH-NET PRESERVATIVES. 49 



Table 22. — Tensile strength and breaking length of all lines tested.^ 



S3rmbol and treatment. 



Freshly treated. 



Tensile 

 strength. 



Breaking 

 length 



Exposed one month. 



Tensile 

 strength. 



Breaking 

 length. 



A — White line, untreated control 



B — Copper oleate 7 per cent 



C — Copper oleate 7 per cent: 5 per cent oil, 1-1000 cresol 



B — Copper olcate 1 1 per cent 



E — Copper oleate 11 per cent, 2 per cent oil 



F — Coal tar 50 per cent, benzol 50 per cent 



G — Pine tar 50 per cent, benzol 50 per cent 



H — Coal and pine tar 25 per cent each, benzol 50 per cent 



I — Quercitron and potnssium bichromate 



J — Petroleimi product No. 1 



K — Waterproofing material 



L — Dutch method 



M — Copper oleale 7i per cent 



N — Copper oleate 12 per cent, 5 per cent oil, 1-1000 cresol 



O — Copper oleate V2\ per cent 



P — Copper oleate 12| per cent, 5 per cent oil 



Q — Copper paint No. 1 



R — Copper paint No. 2 



S — Gilsonite 



X — Petroleum product No 2 



Y — Copper oleate 15 per cent, benzol 35 per cent, coal tar 50 per 



cent 



Z — Copper oleate followed by coal tar 



AA — Copper oleate 15 per cent 



Pounds. 

 39.3 

 30.1 

 35.5 

 36.1 

 31.4 

 35. 4 

 35.2 

 37.4 

 .39.3 

 39.0 

 43.9 

 38.6 

 34.2 

 3.3.2 

 33.6 

 36.3 

 41.5 

 42.7 

 35.5 

 32.9 



35.0 

 36.0 

 38.0 



Feet. 



32,600 



28,000 



25, 100 



23, 300 



21,000 



17,900 



19,500 



21,800 



2S, 100 



21,700 



27,400 



23,300 



27, 300 



25, 300 



25,000 



26,200 



18,500 



14,300 



21,500 



20, 400 



17,400 

 17,«)0 

 25,700 



Pounds. 

 30.4 

 34.7 

 32.4 

 37.6 

 35.0 

 44.6 

 44.4 

 48.6 

 39.2 

 44.8 

 48.9 

 39.9 

 36.2 

 35.2 

 ~ 36.6 

 37.2 

 41.0 

 47.3 

 28.2 

 35.0 



44.5 

 40.0 

 40.0 



Feet. 

 25,200 

 27,000 

 22,900 

 24,600 

 23,200 

 22,700 

 24,500 

 28,300 

 28,000 

 25, 300 

 30,400 

 23, 6(K) 

 28,900 

 26,900 

 27,300 

 26,900 

 18, 200 

 15,800 

 15,700 

 21,700 



22 300 

 19,400 

 27,000 



> The figures herein are averages from all the series studied. 



It will be seen that those lines treated with tar or copper paint 

 are of high tensile strength, especially after 30 days, yet the breaking 

 length, w^liich takes added weight into account, is comparatively low. 

 Unexposed, untreated cotton line has a breaking length of 32,600 

 feet. If the increased strength of the line caused by application of 

 tar and copper paints were proportional to the increased weight, the 

 breaking length should be at least equal to that of the untreated 

 lines, 32,600 feet. It is seen that tliis is not true for any of the pre- 

 servatives when freslily applied. After a month's exposure many of 

 the lines, such as tar, show an improvement, because of increasing 

 binding on the fibers in comparison with the wliite line, which begins 

 to weaken very soon. The copper oleates here show up well, wliile 

 the copper paints, by their excessive weight, give poor results. 



It can be concluded from this section of the paper that weight is an 

 important factor in net preservation ; that although some preservatives, 

 like tar and copper paint, increase the tensile strength of lines by 

 binding the fibers together, this increase of strength does not com- 

 pensate for the increased weight imparted to the lines. It may 

 also be concluded that tar increases w^eight markedly and so does 

 copper paint. Copper oleate and the tanning methods are best in 

 this particular, wliile the petroleum products and gilsonite are 

 intermediate. 



SHRINKAGE CAUSED BY APPLICATION OF PRESERVATIVES. 



Many substances applied to fines as preservatives cause some 

 shrinkage. As stated in connection with the description of the 

 experiments, the samples were always measured to length while under 

 a strain of 2 kg. (4.4 pounds). The standard used w^as a steel tape 

 50 feet long. The measurements, being made before and after treat- 



