iSlO. 3 (1921) MANUFACTURE OF FISH OIL AND GUANO 175 



58. (3) The re-boiling of the oil for sterilising purposes is very 

 defective and scorches still more of the oil ; it is often performed in 

 vertical cylindrical pans, heated by an open wood fire the flames of 

 which play around the bottom and sides of the pan ; it is obvious 

 that the oil in immediate contact with the sides is very apt to be 

 badly scorched, 



59. (4) The separation of organic matter (fragments of fish, 

 etc.) and dirty water, is apt to be imperfectly carried out ; ordinari- 

 ly, except where special instruction has been given by Fisheries 

 officers, the separated oil is never washed, and the dirty oil is kept 

 in wide pits which, though they may be covered with mats, 

 necessarily admit the air pretty freely : the oil gradually deposits 

 much of the impurities and water, but in the long process, gradual 

 decomposition of the impurities occurs which gives an unpleasant 

 odour to the oil, while the water, impurities, and air together cause 

 rapid hydrolysis of the oil with consequent very great acidity (and 

 rancidity) which may amount to as much as 50 per cent of free 

 acids. It is because of this fact that means are being sought to 

 counteract the acidity of the oil, whereas the true remedy is to 

 attack the causes of acidity : acidity once set up can, of course, be 

 neutralized by sodium salts, but this is a source of expense, while 

 the rough soaps so formed are generally of little use or profit in 

 such small factories, and there is very little if any commercial out- 

 let for them. As shown below the oil should be thoroughly washed, 

 freed from suspended water and stored in closed barrels. 



60. (5) The want of a series of separating pits or tanks causes 

 imperfect separation of the dirty water from the oil, with the result 

 shown in item (4) supra, and with consequent loss to the manufac- 

 turers. It is frequently found by purchasers of oil that at the 

 bottom of the kerosene tins in which the oil is frequently packed 

 there is a stratum of dirty water ; for this a percentage of the price 

 is deducted or a lower price is fixed. Purchasers moreover are 

 generally aware of the bad results on the character of the oil and 

 reduce the price of oil found with this residuum, 



61. (6) The want of proper barbecues (drying grounds) causes 

 loss to manufacturer and purchaser. For if the guano is dried 

 upon the sand, a certain quantity of sand is, either by accident or 

 necessity or design, mixed with the guano ; this forms an adultera- 

 tion which not only causes a reduction in price, but spoils the 

 reputation of both manufacturer and product : this is further dealt 



