3- inch boat-type propellers mounted on a 5/8 inch shaft 28 inches 

 in length, was clanqsed aver the side of the barrel. 



For the separation of the oil frcra the liquor upon completion of 

 the digestion, a DeLaval oil purifier. Model No. 202, was employed. 



Procedxre for Alkali Digestion 



The digestion procedxire adopted as standard for the preparation 

 of the samples of oil from the cannery offal was as fo]_lows: 



1. The salmon waste to be processed and an equal wei^t of 

 potable water were placed in the digestion barrel, 



2. The stirrer motor was started and the steam turned on. 



3. A NaOH solution was added. This was made by mixing one-half 

 gallon of water with sodium hydroxide flakes equivalent to 

 1.5 percent of the weight of the waste. 



4. Heating was continued for 15 to 30 minutes at fvHl steam 

 pressure until contents of the barrel had reached 200° F. 



5. Heating at 200°F. with agitation was continued until a 

 sample of the liquor showed few, if any, solids other than 

 bone particles remaining. The digestion time was 70 to 90 

 minutes depending en the size of the heads and the initial 

 temperature of the offal. 



6. When the test sample of the liquor indicated complete diges- 

 tion, the heating and agitation was discontinued and the liq- 

 uor was allowed to stand for 10 minutes to facilitate settl- 

 ing out of solids (bony materials for the most part). 



7. Meanwhile the centrifuge had been started and thoroughly 

 heated by the passage of 10 ^llons of hot vater (210°F) 

 through the machine. 



8. The contents of the barrel (other than, the solids) were 

 passed through the centrifuge. 



9. The oil recovered was weighed, the color was noted, and the 

 samples for addition to the pack of canned salmon were her- 

 metically sealed in tin cans. 



Procedure for Boiling Method 



The same equipment was used as in the alkali digestion method. The 

 procedure differed only in that no sodium hydroxide solution was added. 



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