128 Extracts from the Journals. [Jan., 



" Several fat oils, mixed with one or two per cent of sulphuric 

 acid, assume instantly a dark green or brown hue, and, when 

 allowed to stand quietly, deposite a coloring matter, after some 

 time. It consists in a chemical combination of the sulphuric acid 

 with a body thus separated from the oil, which becomes, in con- 

 sequence, more limpid, and burns with a brighter flame, especially 

 after it is washed with steam, and clarified by repose or filtra- 

 tion. Any remaining moisture may be expelled by the heat of a 

 water bath." 



" Oil of colya is obtained from the seeds of hrasaica campestris, 

 to the amount of 39 per cent of their weight. It forms an ex- 

 cellent lamp oil, and is much employed in France." 



" Flemp seed oil has a disagreeable smell, and a mawkish taste. 

 It is used extensively for making both soft soap and varnishes." 



" Linseed oil is obtained in greatest purity by cold pressure: 

 but by a steam heat of about 200 degrees Fah., a very good oil 

 may be procured in large quantity. The proportion of oil usually 

 stated by authors is 22 per cent of the weight of the seed; but 

 Mr. Blundell informs me, that, by his plan of hydraulic pressure, 

 he obtains from 26 to 27. When kept long in a cask partly 

 open, it deposites masses of white stearin along with a brownish 

 powder. The stearin is very diflicult of soponification." 



" Mustard seed oil. — The white or yellow seed affords 36 per 

 cent of oil, and the black seed 18 per cent." It is perfectly 

 bland, and is used in the woolen factory, for soap-making, etc. 



" There are three kinds of olive oil in the market. The best, 

 called virgin salad oil, is obtained by a gentle pressure in the 

 cold: the more common sort is procured by stronger pressure, 

 aided with the heat of boiling water; and, thirdly, an inferior 

 kind, by boiling the olive residuum or rnarc, with water, whereby 

 a good deal of mucilaginous oil rises and floats on the surface. 

 The latter serves chiefly for making soaps. A still worse oil is 

 got by allowing a mass of bruised olives to ferment before sub- 

 jecting it to pressure." 



" Oil of almonds is manufactured by agitating the kernels in 

 bags, so as to separate their brown skins, grinding them in a mill, 

 then enclosing them in bags, and squeezing them strongly be- 

 tween a series of cast iron plates, in a hydraulic press; without 

 heat at first, and then between heated plates. The first oil is the 

 purest, and least apt to become rancid. The volatile oil of 

 almonds is obtained by distilling the marc or bitter almond cake, 

 along with water." 



Linseed, rape seed, and other oleiferous seeds, unless in a very 

 few large establishments, are still treated in the old manner, in 

 this country — by pounding in hard wooden mortars with pestles 

 shod with iron, as in the rice mills, set in motion by a shaft driven 



