PRESERVATION OF FISH NETS. 31 



idly from the net, and no method of (ixin*!; it is known. The net is 

 oily or irroasy foi- some time after it is treated and is theVefore ohjec- 

 tional)Ie to handle. 



Concerning the mode of application of creosote, Cunningham says: 



There aro many dilTeronl ways of applyin.tr tlio j^ivon oil or creosote to the 

 nets; the net may be wel! <'utche(l tirst, tlion dried, soaked in tiie green oil 

 when dry, then passed tliroujih a wrinjrinfr machine, and spread out to dry; or 

 tlie net may be passed straifiht from liot cutcb, witliout drying?, tliroush the 

 green oil, and then dried, or, instead of tlie oil alone, a mixture of tar and 

 green oil may he us»h1. In whatever way it was applied I found pieces of net 

 treated with green oil had los.t but very little strength after two months' 

 exposure in Newlyn Harbor. 



The principal preserving matters in creosote that comes from wood 

 go over in the smoke when the wood burns in a smoldering fire. 

 Upon this fact is based a method using smoke.* 



It is stated in the articles referred to that this method had been 

 used on the Gulf of Courland for many years in houses that had no 

 chimneys by allowing the smoke to go through passages into a loft 

 where the nets were hung. A direct method of applying the smoke 

 is to fasten the net to the underside of boards which are supported 

 above a smoking wood fire. 



While this method appears to be primitive, there is nothing chemi- 

 cally unreasonable about it, and it may be that under certain circum- 

 stances the method would be applicable to-day. It would certainly 

 be much better than nothing, provided the nets were not allowed to 

 be overheated during the smoking process. It would be necessary to 

 repeat the treatment, perhaps several times a year. The method has 

 the advantage of depositing upon the fibers the volatile antiseptic 

 substances of tar, without the heavy thick parts, and it would ap- 

 pear less likely to shrink the nets. 



COPPER SULPHATE. 



It was noticed in the figures of Lindeman, given above, that hemp 

 threads were improved by every method that improved cotton 

 th.reads; only one preserving material had a more marked effect on 

 hemp than oil cotton — that is, coi)per sulphate (or copper vitriol, blue- 

 stone, blue vitriol, etc., as it is variously known). This substance 

 lias long been used for nets, alone or in combination with other sub- 

 stances. According to a quotation in the Norsk Fiskeritidende 

 (1906) this is used in Norway for the treatment of salmon nets. One 

 kilogram (2i pounds) of copper sulphate is dissolved in a barrel of 

 water. The nets are treated with this by allowing them to lie in it 

 overnight. They are put into the sea as soon as they are taken from 

 the bath, without preliminary drying. Lindeman's figures show that 

 the method does not deserve serious consideration. 



What is perhaps of mucji more importance is a method of using 

 copper sulphate in combination with soap. A method of this kind is 

 said to have been used in the French sardine industry to give the nets 

 a color. Oils consist of two parts, glycerin combined with fatty acids. 

 When the glycerin is taken out, and soda or potash substituted for it, 



" Seo Mitthcilumjcn des Wostprenssisflicn Fischerei-Vereins (1896), Deutscher Fischerei- 

 Vercin (1S85), and Norsk Fiskcritidonde (1896). 



