46 



U. S. BTJREAU OF FISHERIES. 



INCREASE IN WEIGHT CAUSED BY APPLICATION OF PRESERVATIVES. 



Among the properties of textiles that make them suitable for 

 fishing is lightness. A light net is more easily and more rapidly- 

 handled than a heavy one, and consequently less labor is required 

 to handle it. Since a net must support its own weight, the weight 

 added to a net in the substance of a preservative adds just so much 

 to the load to be carried by the net. 



It is therefore important to determine the increase in weight 

 caused by preservation and to select the preservatives that impart 

 least weight to the nets, other conditions being the same. In all 

 the series of experiments so far described in this paper this factor 

 was determined by weighing the sample lines before and after treat- 

 ment. These weighings were made on the analytical laboratory 

 balance, but the Imes were not dried to constant weight. It was 

 found by experiment that, unless elaborate precautions were taken, 

 the perfectly dried sample reabsorbed moisture so rapidly from the 

 air that accurate weighing was impossible. Since it was impractical 

 to use weighing bottles to prevent this and would be improper to 

 heat the treated nets to the temperature required for drying, the 

 samples were weighed in the air-dry condition. 



Table 21 gives the results of the determinations of increase in 

 weight of cotton and linen lines caused by the preservatives. These 

 results are shown graphically in Figures 30 and 31. 



Table 21. — Increase in weight of cotton and linen lines caused by application of preserva- 

 tives. 



COTTON LINES. 



LINEN LINES. 



Symbol and treatment. 



Beaufort. 



Woods 

 Hole. 



Putin 

 Bay. 



Average. 



V — Copper oleate 12J per cent in gasoline, 5 per cent paraffin oil. . 



V — Quercitron and potassium bichromate 



W — Dutch method 



BB — Petroleum product No. 2 



CC — Copper oleate 15 per cent in gasoline 



30.8 

 15.6 



26.2 



31.2 

 35.7 

 22.0 



29.8 

 39.4 

 23.3 



30.8 

 15.6 

 29.0 

 37.5 

 22.6 



