FIXED OILS. 221 



known plant, which is so rapid in its growth and in 

 coming to maturity. In August the full and ripe 

 seed-vessels invite the hand of the reaper. The 

 poppy-heads are cut as they stand in the field, the 

 gatherers receiving them in their aprons, from which 

 they are removed to bushel baskets, and conveyed to 

 a large cloth spread out for their reception. They 

 are then put in corn-bags, and are either trodden by 

 men and children in sabots (wooden shoes) or well 

 bruised by a mallet or a flail. By these means the 

 heads are confined and cannot fly from the stroke 

 imposed, while in being thus bruised their seed is not 

 scattered abroad and wasted. The seeds being 

 entirely separated are taken to the mill and expressed 

 as soon as possible, since the fresher they are the 

 more oil they yield. In extracting the oil it is of con- 

 sequence that the mill, press, and bags be perfectly 

 clean. From two pounds of seeds seven ounces of 

 oil may be expressed. It is of the same specific 

 gravity as linseed oil. This oil is more especially 

 valuable to the varnisher, since it has no colour to 

 injure the delicacy of his preparations, and has like- 

 wise the property of drying in a greater degree than 

 most other oils. Those extracted from walnuts and 

 from linseed are likewise what are called drying oils. 

 In the northern parts of France this oil is very much 

 used by soap-boilers. 



NUT OIL. 



The kernels of walnuts and hazel-nuts yield an 

 oil very abundantly, which is extracted by means of 

 a screw-press similar to that used for olives. This 

 oil, as well as the oil of poppies, is much esteemed 

 by varnishers from its being clear and colourless. It 

 is likewise used for the mixing of flake white and 

 other pigments, where the clearness of the colour is 



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