No. 3 (I921) MANUFACTURE OF FISH OIL AND GUANO I6I 



138 lb. dry scrap, containing 10 per cent moisture, per 1,000 fish 

 weighing^conventionally — 666 lb. : this gives 20*7 Per cent. Again 

 from 12,000 to 15,000 fish, or 4 to 5 tons, yield I ton dry scrap, being 

 a percentage of 25 to 20 per cent. It would seem that the very 

 high proportion of 25 per cent must be due to contents of moisture 

 above the normal 10 per cent. A million fish or 333 U.S.A. tons 

 are said to yield between 75 and 85 tons ; the mean of 80 tons gives 

 22 per cent. Hence from 22 to 20 per cent of the raw fish weight 

 seems to be the average yield of dried scrap. This nearly corre- 

 sponds with Indian yields from sardine. 



29. Owing to difficulties of drying, cost of plant, and objections 

 of neighbours to the vapours and odours, a great deal of the wet 

 scrap from the presses is not dried but acidulated with sulphuric 

 acid, at the rate of about 40 to 60 lb. strong (commercial) acid per 

 1,000 lb. of wet scrap ; this dissolves the bones and prevents decom- 

 position and the attacks of flies, and fixes the ammonia ; it has the 

 disadvantage of weight and moistness. During 1912 there were 

 manufactured 50,885 short tons of dried scrap valued at Rs. 91 per 

 ton, and 37,536 tons of acidulated scrap worth Rs. 48 per ton ; this 

 would equal about Rs. 102 and Rs. 54 per ton of 2,240 lb. Well pre- 

 pared and well dried scrap should contain 8 to 10 per cent nitrogen 

 (10 to 12 units of ammonia) and 9 to 10 per cent phosphoric acid; 

 the average is said to be about 8 and 8*5, respectively. The above 

 are pre-war prices, and are much higher now (1920). 



30. The fish scrap has occasionally been used as cattle and 

 chicken food, but apparently to no great extent. It is mostly 

 ground up and used as an ingredient in compound or complete 

 manures. It is said that about 250 lb., worth Rs. II or 12, are used 

 to raise one bale (400 lb.) of cottpn lint. 



31. Oil — Oil, originally a mere by-product in the manufacture 

 of fertilizer from menhaden, has become of equal importance. As 

 described above, the fish are cooked and pressed, and during the 

 latter process the oil and water run out, are received in channels 

 on the cement floor, and thence fall to the receiving tank, usually 

 on the basement floor. If the cooked stuff is allowed to drain 

 before pressing (paragraph 19 supra), the drained oil and water are 

 similarly received, possibly in a separate tank as drained oil 

 is usually better than pressed oil. In the receiving tank the 

 oil and water and most of the solid impurities separate to a large 

 extent, but a series of separating tanks are needed to complete the 



