658 LINSEED OIL 



or other antiseptic solutions, are used for antiseptic dressings. 

 Oakum, consisting of detached fibres of old ropes, when 

 treated with Stockholm tar, is also a cheap antiseptic 

 dressing. 



Lint seeds are about two lines long, smooth, and shining, 

 of a brown colour and oval shape, flattened laterally, and 

 pointed at one extremity. They are inodorous, but have 

 an oily, mucilaginous taste. They consist of about 20 per 

 cent, of mucilage, wholly present in the envelope of the 

 seed, and hence only properly extracted by prolonged 

 steeping or slow boiling ; 20 of albuminoids, a little sugar, 

 25 to 30 of oil, contained in the albumin and embryo ; 

 5 to 6 of mineral matters, chiefly phosphates, mostly stored 

 in the husks ; 5 to 8 of fibre, and 8 to 10 of water. Crushed 

 linseed should yield not less than 30 per cent, of oil when 

 exhausted by carbon bisulphide. The seeds, ground and 

 pressed without the aid of heat, produce about 25 per 

 cent, of oil of the best quality ; steam heat extracts 25 to 

 35 per cent. The residual linseed cake, or oilcake, con- 

 tains 10 to 13 per cent, of oil. 



Linseed oil is viscid, has a pale-yellow colour, a faint 

 but distinct odour, and a bland taste. Specific gravity 

 0*930 to 0*940. It consists largely of olein, or of a variety 

 recognised as linolein. Although it does not solidify until 

 cooled to 15 or 20 Fahr., at ordinary temperatures 

 it oxidises and becomes viscous, hence receiving the title 

 of a drying oil. This drying property is much increased 

 by boiling, or heating it with litharge or black oxide of 

 manganese. It is insoluble in water, soluble in ten parts 

 alcohol (90 per cent.), in one and a half of ether, and in 

 oil of turpentine. Boiled with alkaline solutions it forms 

 soaps. Mixed with an equal quantity of lime water it forms 

 Garron oil, a useful dressing for burns and scalds. Exposed 

 for some time to a high temperature it becomes a dark, 

 tenacious mass, which, when mixed with lamp-black con- 

 stitutes printers' ink. It is sometimes adulterated with 

 rapeseed oil, but is more commonly of inferior quality from 

 rancidity, from preparation at a high temperature, or from 

 presence of impurities. 



ACTIONS AND USES. Linseed and linseed cakes are valu- 



