260 THE FEEDING OF ANIMALS 



the annual production in this country was about 19,500,- 

 000 bushels in 1909, contains a very high percentage of oil, 

 ranging in the analyses so far made from 22 to 40 per 

 cent. The average is variously stated by different com- 

 pilers at from 33 to 37 per cent, and the mean of these 

 two numbers is probably fairly correct. On this basis 

 a bushel of flaxseed, weighing fifty-six pounds, contains 

 nineteen and one-half pounds of oil and thirty-six and 

 one-half pounds of other substances. 



354. Extraction of linseed oil. — ^Linseed oil is obtained 

 from the seed by both the pressure and extraction methods. 

 The oldest method was to subject the cold crushed seeds 

 to a heavy pressure, which expressed from 70 to 80 per 

 cent of the oil, leaving a cake containing from 10 to 15 

 per cent. Later the warm pressure process was intro- 

 duced, which consists of moistening the crushed seed, 

 heating it to from 160° to 180° F., and submitting it to a 

 pressm-e of 2,000 to 3,000 pounds to the square inch. This 

 improvement increased the output of oil from a given 

 quantity of seed, the amount expressed being about 

 90 per cent of the whole, leaving a cake containing from 

 6 to 7 per cent. The latest and most effective process is 

 the extraction of the oil by a light naphtha. The seed is 

 crushed and heated as in the warm pressiu-e method, and 

 the oil is then extracted by repeated leachings with 

 naphtha until the residue when dry contains only about 

 3 per cent of oil. The naphtha is thoroughly driven from 

 this residue with steam so that the resulting meal is 

 entirely free from odor and is as palatable as the residue 

 from the pressure process. 



366. Old process vs. new process linseed meaL — 

 The terms "old process" and "new process" are now 

 applied to linseed meal, the former referring to that made 



