14 



U. S. BUREAU OF FISHERIES. 



It is apparent, in the first place, that the effect of the sea water 

 at Key West is much more severe than that of the weather at Wash- 

 ington. The untreated line and also those lines treated by quer- 

 citron and potassium bichromate, I, petroleum product, J, as well 

 as the proprietary waterproofing material, K, were all but com- 

 pletely rotten in 18 weeks, though a two or three months' test (as 

 was done in the European experiments) would have shown them to 



52 



so 



48 



46 



44 



42 

 40 

 38 

 36 

 34 

 32 

 30 

 28 

 26 

 24 

 22 

 20 

 16 

 16 

 14 

 12 



15 



18 



3 6 9 12 



WEEKS EXPOSED 



Fig. 3. — Tensile strength of cotton lines exposed in sea water at Key West, Fla. 



be good. The Dutch method, L, which deposits a little copper in the 

 lines, was somewhat better, though lines treated by it, too, showed 

 marked deterioration, especially after the fourth month. The only 

 preservative that brought the samples through four and one-half 

 months' exposure unimpaired in tensile strength were the three tars, 

 F, G, H, and the copper oleate, B, C, D, E. The difference between 

 the tar and the copper oleate is that the tar stuck the fibers together, 



