24 THE FAT OF MILK. 



By the action of bromine di-brom-stearic acid is formed ; this 

 is a heavy yellow oil, which has not been crystallised. By 

 reduction with zinc and hydrochloric acid oleic acid, is again 

 formed. Oleic acid also absorbs iodine from Hubl's and Wijs' 

 reagents, and is said to form chlor-iodo-stearic acid. 



Strong sulphuric acid acts on oleic acid, forming stearo-sul- 

 phonic acid or sulpho-stearic acid ; on boiling with water, sul- 

 phuric acid is split off and hydroxystearic acid is formed, with 

 other products. 



When oxidised by alkaline potassium permanganate di-oxy- 

 stearic acid is formed. 



The salts of oleic acid behave with water in much the same 

 way as the salts of stearic and palmitic acids. All the oleates 

 are soluble in alcohol, and those of copper, lead, and zinc are 

 soluble in ether. 



By the action of fused alkalies oleic acid is split up into salts 

 of acetic and palmitic acids. 



Nitrous fumes act on oleic acid in a characteristic manner ; 

 the liquid oleic acid is transformed into the isomeric solid 

 elaidic acid melting at 45 and boiling at 288 C. at 100 mm. 

 pressure. 



Baruch has proposed the followirg formulae for oleic and 

 elaidic acids : 



Oleic Acid. Elaidic Acid. 



CgHjY C H CgJTjij C H 



H C (CH 2 ) 7 COOH COOH (CH 2 ) 7 C H 



Acid of the Series, Cr'H 2w _ 3 COOH Linolic Acid, 

 C 17 H 31 COOH. It is not known whether this acid exists nor- 

 mally in butter fat ; if so, the proportion is probably not large. 

 It, however, is present in many vegetable oils, and will thus 

 be a constituent of margarine. 



Linolic acid is an oily substance of slight yellow colour, having 

 a faint acid reaction ; it dissolves readily in alcohol and ether. 

 It remains fluid at low temperatures. 



The salts of linolic acid resemble those of oleic acid, but are 

 more soluble in alcohol and ether. Nitrous acid does not produce 

 a solid acid. Both the acid and its salts readily absorb oxygen 

 from the air, and form resinous substances. 



Linolic acid absorbs 4 atoms of bromine, forming tetra-brom- 

 stearic acid, which is a crystalline substance melting at 114 to 

 115 ; from this linolic acid can be prepared by reduction with 

 zinc in a solution of hydrochloric acid in alcohol. 



Acid of the Series, C M H 2 _ 5 COOH Linolenic Acid. 

 This occurs in vegetable oils. It is a liquid, even at very low 



