1846.] Vegetable Oils. 127 



our farm practice; and the manufacture of oil is one that can be 

 advantageously introduced amongst us — requiring no immense 

 buildings, or other great outlay, no introduction of free and ex- 

 pensive operations, and the oil and oil-cake can all, or a great 

 part of it, be consumed amongst us. It needs but a sufficient 

 supply of seeds grown in the south, to cause the immediate esta- 

 blishment of oil mills throughout that section. 



Should we have war, the price of vegetable oils will be at 

 once enhanced; and in such an unhappy event, as war, it be- 

 comes of great importance that we have a sufficient home supply 

 of oil, as of every other necessary of life. 



The following forms part of a list of those plants which yield 

 the ordinary unctuous oils of commerce, as given in Ure's Dic- 

 tionary of the Arts, Manufactures, etc.: 



Linnm usitatissum at perenne — linseed oil, 11 to 26 pr. ct. 



Canabis sativa — hemp oil, 14 to 25 " 



Sesamum orientale — oil of sesamum or bene, 50 " 



Cucurbita pepo and melapepo — cucumber oil, 15 " 



Helianthus annuus and perennis — oil sunflower, 15 " 



Brassica napus and campestris — rape seed oil, 33 " 



Ricinus communis — castor oil, 62 " 



Arachis hypogasa — ground nut oil, 00 " 



Gossvpium barbadense — cotton seed oil, 00 " 



Brassica campestris oleifera — colya oil, . , 86 to 40 " 



Brassica prfeccox — summer rape seed oil, 30 to 36 " 



Sinapis alba, nigra, etc. — mustard seed oil, 15 to 33 " 



Cucurbita pepo — pumpkin seed oil, 00 " 



Madia sativa, 00 " 



To these may be added, as affording abundance of oil, though 

 from the fleshy pulp surrounding the seed, and not from the seed 

 itself — the olive, olea Eueopea. There are various nuts, too, 

 which afford a large proportion of oil, as the walnut, almond, 

 beech, plum, cherry, apple, horse-chesnut, or buckeye, etc. 



" Nuts contain about half their weight of oil; the seeds of the 

 brassica oleracea and cam'pe.r.tris, one-third; the variety called 

 olya, in France, two-fifths; hemp seed, one-fourth; and linseed, 

 from one-fourth to one-fifth.'' 



" In close vessels, oils may be preserved fresh for a very long 

 time, but with contact of air they undergo progressive changes. 

 Certain oils thicken, and eventually dry tnto a transparent, yel- 

 lowish, flacicle substance, which forms a skin upon the surface of 

 the oil, and retards its farther alteration. Such oils are said to 

 be dryincr or siccative, and are used on this account in the prepa- 

 ration of varnishes and painters' colors. Other oils do not grow 

 dry, though they turn thick, become less combustible, and assume 

 an offensive smell. They are then called rancidJ" 



