Taylor and Wells. — Preservation of Nets and Lines. 45 



Table III. — Tensile strength in pounds of No. 24 cotton lines put down 

 IN the sea at Key West, Florida, November 7, 1921. 



[One of each was taken up each 3 weeks over a period of 18 weeks. Each figu are is hetverage of 

 15 tests, except A, the unexposed and untreated ocntrol .which is the average of 60 breaks.] 



By way of demonstrating the effectiveness of copper in the 

 lines, the reader is asked to compare Bull's method v^^ith the 

 Dutch method. Bull's method is bark extract, quercitron, applied 

 to the line, and mordanted by oxidation with potassium bichro- 

 mate. The original formula calls for a small amount of copper 

 sulphate, but this was omitted so as to have a control on the 

 effect of copper. The Dutch method is the same bark extract 

 (quercitron), mordanted with ammoniacal copper sulphate in- 

 stead of potassium bichromate. The line treated by the Dutch 

 method contains copper tannate, those treated by Bull's method 

 contain no copper. In Fig. 3 compare lines I and L. 



Experiment at Beaufort, N. C. Fig. 5 shows the results 

 (given in Table IV) of experiments at Beaufort, N. C, February 

 15 to August 15, 1922. In this series, fourteen preservatives and 

 a control were exposed as follows: (A) White line, control, (F, 



