No. 3 (192 1) MANUFACTURE OF FISH OIL AND GUANO 223 



ghee and oil have been taken from Egyptian tombs where they 

 were placed from 2,500 to 4,000 years ago ; being dry oils (ghee, 

 etc.) and kept sealed in the dry atmosphere of Egypt and in the 

 total darkness of a tomb, they were quite unchanged and free from 

 acidity (only one was slightly acid) and rancidity. On the other 

 hand as shown in paragraph 94 and as is otherwise well known, 

 the badly stored fish oils of the small coastal factories may be 

 found within a year to contain over 50 per cent of fatty acids and 

 to be hopelessly rancid and consequently of low money value. 

 Hence both the proper initial preparation of the oil and its proper 

 storage are of great importance. Proper preparation has been 

 dealt with above, and will be further dealt with s.v. " refinement" ; 

 storage has yet to be considered. 



122. The first stage of oil deterioration is the formation of fatty 

 acids by the decomposition of the oil ; this itself is a real deterio- 

 ration except when used for certain technical industries such as 

 soap-making; it is bad for leather work, lubrication, and for all 

 edible purposes. This decomposition is caused mainly by enzymes 

 or chemical ferments which are active in the presence of light, air, 

 and moisture. As shown above, properly prepared oil, washed 

 and separated from its main impurities, dried, and perhaps filtered, 

 will keep good indefinitely if stored in closed receptacles ; hence 

 ail oil which it is desired to keep free from acidity should, after 

 purification, drying, etc., be stored not in open pits or tanks loosely 

 covered with mats, but in iron or masonry tanks, tight wooden or 

 steel barrels, closed kerosene oil tins, etc. If the finished oil has 

 been heated for drying purposes as suggested in paragraph 119, it 

 should be run direct into receptacles, and these should, as soon as 

 possible, be filled to the brim so as to exclude air, and closed. 



If the separation of water and drying has not been quite 

 complete, it will be found, after a settling period, that dirty water 

 has accumulated at the bottom of the receptacle ; this should be 

 drawn off as soon as possible by means of a tap. Oil thus stored, 

 should, if it has been properly prepared, washed, and dried, be far 

 superior to ordinary oil stored in pits, and should get a better 

 price. 



123. Recapitulation. — To sum up ; oil should be prepared from 

 fresh, untainted fish, and, if delay is likely to occur, the fish 

 should be freely salted ; the oil should be rapidly separated from 

 the fish mass in the operations of obtaining the oil ; the water, full 



