150 Feeds and Feeding. 



ponred and allowed to drain out at the bottom of the cylinder. 

 Naphtha dissolves the oil from the ground flax seed, being repeat- 

 edly added until nearly all the oil is extracted. After this has been 

 accomplished, steam is let into the percolator, and the naphtha 

 which did not drain off is gradually driven out of the mass as 

 vapor. This is so effectively done that no smell of naphtha is 

 noticeable in the residue. From the percolators, after steaming, 

 the meal is transferred to driers, from which it is elevated to the 

 meal bins. This by-product is known as '' new-process " oil meal. 



202. The swelling process. — WolP gives the following simple 

 method of ascertaining whether oU meal is new- or old- process: 

 "Pulverize a small quantity of the meal and put a level table- 

 spoonful of it into a tumbler; then add ten tablespoonfuls of 

 boiling hot water to the meal, stir thoroughly and leave to settle. 

 If the meal is new-process meal, it will settle in the course of an 

 hour and will leave about half of the water clear on top." Old- 

 process meal will remain jelly-like. 



203. Adulteration of oil meal. — Adulteration of oil meal may 

 be brought about through using immature flax seed or that con- 

 taining weed seed, or, finally, foreign matter may be added to the 

 meal after grinding the cake. Immature flax seed contains starch, 

 while fully mature seed contains none. "Weed seeds contain much 

 starch. If then starch grains are found in linseed meal, it is 

 because of immature flax-seed grains, weed seeds, or both. 



The maiuifacturer of oil meal endeavors to have the flax-seed 

 as free from foreign substances as possible, for the reason that 

 such foreign matter absorbs and holds oU, thereby reducing the 

 amount available. Any serious adulterations of oil meal must 

 therefore occur through the direct addition of foreign material to 

 the meal after the oil has been extracted. WoU found no oil meals 

 purposely adulterated, though he examined many samples. 



204. Relative value of old- and new- process oil meal. — Woll, ' 

 conducting artificial digestion trials with twelve samples of old- 

 process and nine samples of new-process oil meal, found that 94.3 

 per cent, of the protein in old-process and 84. 1 per cent, of pro- 



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