48 



U. S. BUBEAU OE FISHERIES. 



ORIGINAL 

 WEIGHT 



In Figures 30 and 31 the original weight of the line is represented by 

 the height of the polygon up to 100. The diagonally hatched part 

 above 100 represents the weight added by the preservative, and the 



total height of the polygon represents 

 the total weight of the line after treat- 

 ment. 



It is readily seen that certain mate- 

 rials, such as tar and copper paint, very 

 greatly increase the weight of the lines, 

 while others, notably the tanning meth- 

 ods and copper oleate, add very little 

 to the weight. Tar, which shows a con- 

 siderable increase, would probably show 

 even a greaterincrease in weight where 

 it is applied by the hot method. Cop- 

 per paint, which made such a good 

 showing in preservation of tensile 

 strength, here makes a very poor show- 

 ing in that it causes a great increase in 

 weight. 



It was noticed in connection with the 

 data on tensile strength that certain 

 preservatives actually increased tensile 

 strength by their binding effect on the 

 fibers. The preservatives that have the 

 greatest effect in this way are also 

 those that increase weight most. The 

 question then arises. Does the extra 

 tensile strength imparted to the lines 

 compensate for the added weight? 

 Will the extra added strength carry 

 the extra added weight? This ques- 

 tion can be determined by examining 

 the breaking length, which is the length 

 of itself that a line will support. Table 

 22 shows the tensile strength in pounds 

 and breaking length in feet of the un- 

 treated and treated lines before expos- 

 ure; that is, the number of feet of line 

 that will just support itself without 

 breaking, calculated by dividing the weight per foot into the tensile 

 strength in pounds. Similar figures are shown for the same lines 

 after 30 days' exposure. 



Fig. 31. — Increase in weight of linen lines 

 caused by one application of various 

 jireservativcs. U, copper oleate, V2\ per 

 cent solution in gasoline, 5 per cent 

 ])araffln oil; W, Dutch method; V, 

 quercitron and potassium bichromate; 

 BB, petroleum product No. 2; CC, cop- 

 per oleate, 15 per cent solution in gas- 

 oline. 



