percentage of alkali, (soiian hydro:xide) by weight of the salmon waste, 

 was varied from 1 to 5 percent. The digestion was continued until test 

 samples of the liquor indicated complete digestion. 



Particle Size 



Using 1-1/2 percent sodium hydroxide, by weight of waste, in each 

 test, four variations in the particle size of the raw material were tried. 



1) Some tests were nin with the whole waste as it comes from the 

 "Iron Chink" of the cannery. 



2) In other tests the raw material was passed through a Califor- 

 iiia Press Grinder with 7/8-inch hole plate; this 15 hp. grinder 

 handled material far more rapidly than it could be fed by hand, 

 and therefore it was Jmpossible to determine its capacity. 



3) VJhen the whole waste was passed through the Hercules Meat-Bone 

 Chopper the soft parts were well mascerated, the head and other 

 bony parts were sliced thin, but many tail pieces came through 

 whole; this hogger had little difficulty handling the salmon 

 cannery waste. 



4) In order to determine the effect of very fine grinding, tests 

 were run on material that had been passed through a Rietz Dis- 

 integrator with l/8-inch hole screen. Before passing it 

 through this disintegrator, it was necessary to hog the materi- 

 al through the meat-bone grinder. 



Temperature of Digestion 



With each of the variations in particle size of raw material, diges- 

 tions were run at 190°, 200° and 210°F. In each test the digestion was 

 continued until test samples indicated completion of the process. 



Time of Digestion 



In 28 of the experiments the proper digestion time was determined 

 by removing test samples of the liquor. In two pairs of the experiments 

 the effect of the digestion time was specifically considered. Using 1-1/2 

 percent alkali by weight of waste, which had been disintegrated, diges- 

 tions at 200° F. were continued for 30 minutes and for 60 minutes. 



Determination of Oil Content and Oil Yield 



In those tests in which the raw material had been disintegrated or 

 passed through the California Press Grinder, it was possible to secure 

 a representative sample for an oil determination. About five pounds 

 were removed from the ground or disintegrated mass and this was reground 



102 



