2 U. S. BUREAU OF FISHERIES. 



Experimental exposure and testing of lines — Continued. Page. 



Series exposed in fresh water at Put in Bay, Ohio 38 



Water conditions at Put in Bay 38 



Tests with cotton lines 39 



Materials tested 39 



Tensile strength 39 



Flexibility 40 



Wearing quality 41 



Tests with Unen lines 43 



Materials tested 43 



Tensile strength 43 



Summary of results of Put in Bay experiments 44 



Other considerations of importance in judging value of preservatives 45 



Varying rate of decomposition of lines in different localities 45 



Increase in weight caused by application of preservatives 46 



Shrinkage caused by application of preservatives 49 



Time and labor required to apply preservatives 51 



Color imparted to lines by preservatives 51 



Spontaneous heating 52 



Apparatus used for testing 52 



Linseed oil 53 



Copper oleate 53 



Other preservatives 54 



Effect of heat on cotton lines 54 



Discussion of results 54 



General consideration of various preservatives in light of data presented 55 



Tar 55 



Coal tar 56 



Pine tar 56 



Mixed tar 56 



Tanning or barking 56 



Quercitron and potassium bichromate 57 



The Dutch method 57 



Copper paint 58 



Petroleum products 58 



Gilsonite 59 



Copper oleate 59 



Chemical properties and manufacture of copper oleate 61 



Method of applying copper oleate to nets 62 



Grading the several materials as all-round preservatives 63 



Tabular summary 68 



Bibliography 68 



INTRODUCTION. 



Most of the fish taken commercially in the waters of the United 

 States are captured by means of textile gear that is perishable — chiefly 

 cotton and linen. The value of the webbing and lines used by our 

 fishermen, as shown in Table 1, is approximately $14,000,000. When 

 this sum is compared with the value of the annual catch of fish, which 

 for the entire nation is about 2,500,000,000 pounds, valued at $80,- 

 000,000, it appears that the invested capital for gear is very large; 

 boats, houses, machinery, and the like further increase the cost. Not 

 only is this item for textile gear large, but the gear itself is very per- 

 ishable. Many nets wear out in one season; perhaps most nets last 

 less than two full seasons. Such rapid loss of invested capital becomes, 

 therefore, of the nature of overhead expense, which helps to diminish 

 the fisherman's reward for his labor, but which must in the end be 

 paid for, at least in part, by the consumer. When considered from 

 the viewpoint of the individual fisherman, a fishing vessel, or com- 

 pany, the importance of reducing the cost of this item is obvious. 



