LINSEED OIL 509 



higher than 20 ; exposed to the air in thin layers gradually hardens 

 to a transparent varnish ; consists of the glycerides of linolic, linolenic, 

 isolinolenic, oleic, stearic, palmitic and myristic acids ; may be identi- 

 fied by its odour, high iodine value, and by its hardening to a varnish ; 

 may be adulterated with mineral oil, rosin oil and fish oils ; mineral 

 oil may be detected by the rise in unsaponifiable matter ; rosin oil 

 by shaking with alcohol, evaporating the alcoholic solution, dissolving 

 the residue in acetic anhydride and adding sulphuric acid, a red 

 colour indicating rosin oil ; fish oils are difficult to detect (compare 

 Allen, ' Commercial Organic Analysis '). 



Linseed oil is used in pharmacy in liniments and as a laxative. 



Note. Boiled oil is linseed oil which has been heated with litharge or other 

 suitable driers ' to about 150 ; metallic salts of the fatty acids are formed and 

 cause the oil to dry more rapidly. 



ARACHIS OIL 

 (Nut Oil, Ground Nut Oil, Pea Nut Oil, Oleum Arachidis) 



Source, &c. The oil expressed from the seeds of Arachis Tiypogcea 

 Linne (N.O. Leguminosce) . The plant is an annual, attaining 1 m. 

 in height ; the lower flowers develop fruits which bury themselves in 

 the earth and there ripen ; a single plant may produce as many as 

 100 fruits. These contain usually from one to three reddish brown 

 seeds the chief constituents of which are fixed oil (about 45 per cent.), 

 starch and proteids (about 27 per cent.). The seeds are imported 

 chiefly from West and East Africa and from India. The press-cake 

 forms a valuable cattle food. 



Description, &c. The fixed oil is pale yellow or greenish yellow 

 with a nutty odour and taste. Specific gravity 0-916 to 0-921 ; 

 iodine value 83 to 110; consists chiefly of the glycerides of arachic, 

 stearic, lignoceric, oleic, hypogseic and linolic acids. It may be 

 identified by saponifying 1 c.c. with 15 c.c. of N/l alcoholic solution 

 of potash, allowing the mixture to stand for 24 hours at 15-5, heating 

 on a water-bath for 3 minutes and again setting aside, when crystals of 

 (impure) potassium arachate separate. 



ALMOND OIL 



. (Oleum Amygdalae) 



Source, &c. The oil expressed from the Bitter or Sweet Almond. 

 See p. 161. 



Description, &c. Pale yellow, nearly inodorous. Specific gravity 

 0-915 to 0-920 ; iodine value 93 to 100 ; does not congeal above 18. 



