y 



307 Oil from the Seeds of the Sun-Flower. 



the o-eneral principles upon which oil is obtained, by cx~ 

 preffion from vegetable fubftances, it may be proper to ob- 

 ferve, that the kernels of fruits, fuch as walnuts, hickory 

 nuts, filberts, almonds, peaches, &c. and the feeds of many 

 plants, as muftard, rape, poppy, flax, fun-tlower,_&c. con- 

 tain a large portion of mild oil. In order to obtain the oil, 

 the kernels or feeds are commonly rubbed to powder, or 

 ground in mills. They are then put into a ftrong bag, 



made of canvas or woollen cloth, and committed to a prefs 

 betv^een iron plates, by which the oil is fqueezed out, and 

 is received or conduded into a proper vciTel to colled it. 

 The plates of the prefs are often heated, either in boiling 

 water, or before the fire. Many heat the mafli itfelf in a 

 large iron pot, ilirring it about with a ftick or piece of 

 wood, to prevent it's burning, which, when it happens, 

 greatly injures the oil, and gives it a burnt fmell and tafte, 

 or difpofes it to become rancid in a fhort time. When the 

 oil is drawn without the affiftanceof heat,it is known by the 

 name of cold drawn oil, and Is more valuable, than when 

 heat is ufed, but it is not obtained in the fame quantity. It 

 is milder, and may be kept longer without fpoiling. 



In a cold feafon of the year, a certain degree of heat is 

 abfolutely neceffary. But if the oil is defigned for ali- 

 ment or medicine, the plates of the prcfs fhould be heated 

 in boiling water only. When the oil Is Intended for other 



ufes, the plates may be made hotter, as heat expedites the 

 feparation of the oil, and gives a greater produce, but then 

 care fhould be taken not to injure the fubjed by burning. 

 Sometimes the fubjed, when ground, appears almoft 

 like a dry powder. It is then faid to be meagre, and re- 

 quires to be expofed to the vapours of boiling water, which 

 is done either by tying it up in a bag, or putting it into a 

 fieve, and placing It over the fteam. By this impregna- 

 tion, It will yeld it's oil more readily, and in greater quan- 

 tity. The oil maybe eafily freed from any water that may 

 happen to be preffcd out with it, as a fpontaneous repara- 

 tion between them will take place on ftanding for fomc 



•time. ^""^ 







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TJVii 



