39 LINUM USITATISSIMUM 



forms the linseed meal of the British Pharmacopoeia. In the United 

 States Pharmacopoeia the seeds are simply directed to be ground, 

 and the meal, which is there called flaxseed meal, consequently 

 differs from that of the British Pharmacopoeia in containing the 

 oil. The meal containing the oil is to be preferred when used fresh, 

 but it soon becomes rancid by the formation of fatty acids from 

 the oxidation of the contained oil. Linseed meal is greyish- 

 brown in colour. 



Linseed meal is a valuable emollient application. It is very 

 largely used in the form of a poultice to inflamed and suppurating 

 surfaces. It is also employed when mixed with water for luting by 

 chemists. Oil-cake, from containing about 30 per cent, of protein 

 substances, equivalent to 5 per cent, of nitrogen, forms a very 

 valuable food for cattle, for which purpose it is largely 

 employed. 



3. OLEUM LINI. Linseed or flaxseed oil is usually obtained on a 

 large scale by first roasting the seeds to destroy the mucilaginous 

 matter contained in their coats, and then submitting them to 

 pressure, when they yield from 20 to 30 per cent, of oil 

 according to the quality of the seed. The best oil is, however, 

 obtained by pressing the seeds without previous heating, but the 

 yield is not so great, averaging less than 20 per cent, under such 

 circumstances. The oil when obtained without heat is of a very 

 pale amber colour, and when fresh has but little taste or odour ; 

 but commercial oil is usually of a dark yellowish-brown colour, and 

 has a disagreeable odour and a nauseous acrid taste. Its specific 

 gravity is about 0'932. It is soluble in alcohol, but more readily 

 so in ether, and has the property when exposed to the air of 

 drying into a hard transparent varnish, more especially after 

 having been boiled, and still more after having been heated with 

 oxide of lead. Its essential constituents are glycerin and fatty 

 acids, more especially linoleic acid, to which it owes its drying 

 property. 



Linseed oil is emollient in its action, and is a valuable applica- 

 tion to burns or scalds, either alone or mixed with an equal volume 

 of solution of lime (lime-water) . This mixture is commonly known 



