FIXED OILS. 213 



sun-flower seeds, both of which on expression yield 

 a good oil. They are very little liable to dry by 

 exposure to air, and are much employed as pre- 

 servatives against the attacks of moths and other 

 insects. There is a large consumption of rape and 

 other seed oils for this purpose among wool and 

 leather-dressers. 



In America, cotton-seed is now made to yield a 

 very good and serviceable oil ; a machine having 

 been recently invented there for hulling the cotton. 

 The object of this operation is not to get rid merely 

 of the hull or skin, but of the fibres of cotton which 

 adhere to it, and which would absorb and retain a 

 large portion of the oil under the press. Previously 

 to this invention cotton-seed was treated as refuse, 

 and served only for manure. Taking into considera- 

 tion the quantity of cotton produced in the Southern 

 States, and the relative weight of the seed which it 

 surrounds, some estimate may be made of the vast 

 produce of an article now found to be available for 

 useful purposes. 



After the seeds are hulled they are ground and 

 pressed in a machine of the same construction as the 

 Dutch oil-mills. Cotton-seed is much softer, and 

 therefore easier to crush than linseed ; the grinding- 

 stones can accordingly be made smaller in propor- 

 tion to the number of pestles used, than those of the 

 linseed oil-mills. The oil thus extracted is refined 

 by a simple and cheap process, so as to answer all 

 the purposes of the best sperm oil; competent judges, 

 who have carefully compared the two, being entirely 

 satisfied of their equality. 



After the oil has been expressed from the seed, the 

 residue is a nutritive oil-cake; so that a planter who 

 makes four bags of cotton, obtains by these means 

 forty bushels ot good food for his cattle, independent 

 pf the oil which may be produced, 



