FISH-NET PRESERVATIVES. 61 



tar in weight and stiffness. In wearing quality it greatly excels 

 copper paint. It would be a suitable preservative for heavy gear 

 subject to continued severe exposure, such as traps and pound nets. 

 Directions for applying tliis combination are as follows: 



Dissolve 1 pound copper oleate in 1 gallon of benzol (gasoline is 

 not suitable for this purpose). Stir in, cold, 1 gallon of coal tar, 

 more or less, according to the stiffness and weight that is allowable. 

 Dip the net in this combination cold and dry. Avoid fire.* 



CHEMICAL PROPERTIES AND MANUFACTURE OF COPPER OLEATE. 



Cupric oleate Cu (CisHjgO-Os is a green substance of the consistency 

 of beeswax, insoluble in water, soluble in alcohol, ether, benzol, 

 gasoline, carbon tetrachloride, turpentine, oils, etc., forming emerald 

 green solutions. It contains, on the basis of the formula given, 

 10.15 per cent copper, by weight, though the percentage of copper in 

 commercial preparations may vary between wide limits. It has a 

 metallic coppery taste and is poisonous when taken internally, 

 though external exposure to it is apparently harmless. 



Copper oleate may be made in a number of different ways. It is 

 precipitated when sodium oleate and any soluble copper salt are 

 brought together in aqueous solution. Whien prepared in this way, 

 it is gummy and contains much water that is removed only with 

 difhculty. Cupric oxide dissolves in hot acid with formation of 

 copper oleate and water, but it is difficult or unpossible to carry 

 the reaction to completion. Copper acetate and oleic acid combine 

 at an elevated temperature, whereby copper oleate is formed and 

 acetic acid driven off. The latter may be condensed and recovered. 

 This method produces a good product, entirely soluble, but some 

 acetic acid usually remains. Moreover, copper acetate is expensive. 



The method employed in our production of copper oleate was to 

 treat copper carbonate (containing also copper hydroxide) with oleic 

 acid. In this reaction carbon dioxide and water are produced, and 

 both are driven off by heat. Both reagents are obtainable in com- 

 merce in large quantities at a low price. The current (December 30, 

 1922) price of^copper carbonate is 20 cents per pound, and oleic acid 

 (the red oil of conunerce) is 10 cents per pound. The exact pro- 

 cedure as followed in the laboratory in making this material is as 

 follows : 



Into a 5-gallon cojjper steam-jacketed kettle put 4 pounds of dry 

 copper carbonate. Moisten tliis with enough red oil (about 1 quart) 

 to make a paste ; knead the paste with a wooden pestle until all lumps 

 are crushed and the mass is of uniform consistency. Stir in more 

 oil. As the oil is added large quantities of gas are generated, and 

 constant stirring is necessary to keep the contents from running over 

 the sides of the kettle. As the foaming subsides more oleic acid is 

 put in until 15 pounds in all have been added. Steam is now cau- 

 tiously admitted to the jacket, and with constant stirring the mass 

 is kept from foaming over. A thermometer is kept in the mass. 

 When the boihng point of water is reached, bubbles of steam escape 

 rapidly. This bubbling may continue for two hours or more, until 



* Net and twine manufacturers, or others who might be interested in the regular application of this com- 

 bination, should take nutice that continued breathing of the vapors of benzol are narmful, and workers 

 should be protected accordingly by adequate ventilation of workrooms. 



