424 



U. S. BUEEAU OF FISHEKIES 



following preservatives lasted throughout the entire period of the 

 test with almost no diminuation of strength: The four copper 

 oleates (EE, FF, GG, and HH), coal tar (KK), and the copper 

 oleate-coal tar combination (Y). Samples treated with quercitron 

 and ammoniacal copper sulphate (L) and the proprietary water- 

 proofing (JJ) also lasted for six months, although they had suffered 

 a considerable decrease in tensile strength. 



2,3 4 5 



NUMBER OF MONTHS EXPOSED 



Fig. 9.— Tensile strength of cotton lines exposed at Charlevoix, Mich. 



TESTS WITH MANILA HEMP LINES 



Materials tested. — The preservatives and preservative methods 

 tested on manila hemp were copper oleate in four variations (SS, TT, 

 UU, and VV), quercitron and ammoniacal copper sulphate (WW), 

 coal tar (XX), the copper oleate-coal tar combination (YY), and the 

 untreated sample (DD). 



Tensile strength. — The results of the tensile-strength measurements 

 of the individual samples are shown graphically in Figure 10. Here 

 the preservatives rank: higher but in about the same position relative 

 to each other as at Put in Bay. In decreasing order of effectiveness 

 the preservatives tested at Charlevoix arrange themselves in the 

 following order: Copper oleate-coal tar combination, copper oleate, 

 coal tar, and the quercitron-ammoniacal copper sulphate method. 

 The untreated sample lasted longer than the one treated by the 

 quercitron method. 



