OILS, ESSENTIAL. 



OLEIC ACID. 



30 



the natives with the commercial dealings of Europe. The imports of 

 whale oil are decaying, partly on account of the scarcity of whales 

 in the North Atlantic, and partly owing to the increase in the use of 

 vegetable oils. Of the seed oils, a large proportion is now Colza, or 

 rape-seed oil, imported for use in lamps. In 1859 our farmers used 

 95,000 tons of oil cake, in addition to that obtained from oil-mills in 

 this country. Of the 1,270,000 quarters of linseed imported, all but a 

 small proportion was pressed for oil, the seed for sowing being com- 

 paratively small in quantity. In the same year, England exported 

 nearly 8,000,000 gallons of seed oil ; this was nearly all Unseed oil, 

 and was probably mostly for use in house-painting. 



OILS, ESSENTIAL. [ESSENTIAL OILS.] 



OILS, FIXED. [FIXED OILS.] 



OILS, VOLATILE. [ESSENTIAL OILS.] 



O'LEA EUROP.EA. M^/iral Properties of. A peculiar resiniform, 

 balsamic exudation from the tree, the leaves, the fruit, and oil from 

 the fruit, of this tree are all in use, but in Britain the oil only is 

 officinal. The resin contains a peculiar matter termed olirile, a brown 

 ' nd benzoic acid. The leaves ha ve a peculiar crystalline febrifuge 

 substance, useful against intennittents. (' Pharmacopoeia.') The olive 

 oil is itself used to adulterate cod liver oil ; but this is in every way 

 disadvantageous to the patient, as it is quite as apt to cause nausea, 

 and is by no means productive of so much good as cod liver oil. (See 

 ' Lectures on Pulmonary Consumption," by Theophilus Thompson, p. 88.) 



Olive-oil, on account of its high price, is frequently adulterated with 

 poppy or rape oil. The former may be easily detected, if present in 

 the proportion of only 1 per cent., as it retards the solidification of the 

 oil, when a mixture, consisting of 9 parts of nitric and 3 parts of hypo- 

 nitrous acid, is added to 100 parts of the suspected oil. The presence 

 of metals may be detected by sulphuretted hydrogen. For various 

 means of applying these and other testa, see Thomson's 'Organic 

 Chemistry Vegetable Substances/ p. 435 ; and notes in ' Edinburgh 

 Pharmacopoeia.' 



Olive-oil is used in medicine as an emollient, and to form cerates and 

 plasters. It is also used in the manufacture of soap. The finest kiml 

 is much employed with various articles of food, particularly in the 

 countries where it is produced. 



As this oil becomes viscid more slowly than any other vegetable oil, 

 it is used, after being purified, by watch-makers. 



ol. KATES. IDI.II, ACID.] 



OLEEXE. [HKXYI.F.NE.] 



OLKI'IANT CAS. [ETUYLENE.] 



OLEIC ACID. An oleate of glycerin, or olein, this acid forms the 

 greater portion of all drying oils and the fluid part of nearly all fate. 



Olfin or tlain (C 114 H 1M O il ). It was first observed by Chevreul that 



expressed oils and different kinds of fat usually contain two oils of 



different degrees of fusibility, or in other words, two different fatty 



substances ; so that on cooling any expressed oil, one part of it became 



solid, while another portion retained its fluidity. In consequence of 



nervation he concluded that all expressed oils are similarly con- 



'1 ; to the less fuviU<- "il in' gave the name of stearin (from <rriaf, 



suet), and the more fusible he termed tlain (from (\cuor, oil), which 



was afterwards changed to </ ' 



Several methods have been proposed for separating these two sub- 



. When olive oil, fur examplf, is exposed to a low temperature, 



a portion of it becomes solid, and the remainder retains its fluid form ; 



the former is stearin, or margarin, and the latter olein ; these are 



separated by absorbing the liquid part by blotting-paper, and pressing the 



solid portion between folds of this paper till it ceases to render it greasy. 



The olein which the paper has absorlx-d is then to be separated from 



it by boiling it in water, on which the olein floats, and tho ;a|KT sink*. 



11 has scarcely any taste or smell when procured from oils which 



possess these properties only in a slight degree. Its specific gravity is 



solidifies at 27 Fahr., and crystallises in needles. In water it 



is quite insoluble, but alcohol takes it up largely when boiling ; 



by the alkalies potash and soda it is readily saponified, and during 



Iteration oleic acid is formed by a new arrangement of the 



elements of the olein and their action on the elements of water ; and 



these changes occur without the evolution of any gaseous matter. 



On account of the very low temperature at which olein con- 

 geals, it is well adapted for lubricating the wheels of watches, and its 

 tn thU respect is enhanced by its not readily becoming rancid by 

 the action of the air. 



Although olein is frequently regarded simply as terolcate of glycerin, 



1 > ititution is more correctly expressed by regarding it as glycerin 

 i it tit \ 



[ O in which three equivalents of hydrogen are replaced by 



three of the acid radical (C M H JS 0,). Berthelot has indeed succeeded 

 in forming this compound (terolein) artificially, as well as diokin and 

 mono/tin. The processes he adopted have already been described under 

 GLTCERIH; the following formulae will however show the relations 

 the compound* in question bear to each other : 



C.H. 



C.H,' 



C,.H J3 0, f C 3 .H,,0, 



5 { c,.n,,o, 



Glycerin. 



Monolein. 



Diolcin. 



Teroldn. 



Elaiain is 'a solid modification of olein, and is produced when the 

 latter is subjected to the influence of peroxide of nitrogen. 

 [ELAIDIN.] 



Linolein is the name given to the olein of linseed oil ; it contains 

 linoleic acid (C 40 H 39 O a ), differing apparently from oleic acid, but requir- 

 ing farther investigation. 



Oleic acid (HO, C 30 H 33 3 ). The preparation of this acid in the pure 

 state is not an easy matter. Olein obtained in the manner above 

 described still contains small quantities of margarin and stearin, and 

 on saponification with an alkali yields margarate and stearate as well as 

 oleate of the base. One of the best methods consists in saponifying 

 with oxide of lead, digesting the resulting salts in ether for twenty- 

 four hours, whereby oleate of lead only is dissolved ; the oleic acid 

 separated from the latter salt is super-saturated with ammonia, precipi- 

 tated by chloride of barium, the oleate of baryta dried and boiled with 

 alcohol, and the crystalline" plates deposited on cooling finally decom- 

 posed by tartaric acid, when pure oleic acid separates. 



Pure oleic acid ia colourless, inodorous and tasteless. At about 40 

 Fahr. it solidifies into a hard white mass of acicular crystals, but at 

 temperatures above 57 remains as a limpid oleaginous liquid, insol- 

 uble in water but soluble in alcohol or ether. It rapidly absorbs 

 oxygen from the air, acquires a rancid smell and taste, turns litmus 

 paper red, and has its point of solidification gradually lowered to below 

 the zero of Fahrenheit's scale. By heat oleic acid is broken up into 

 several gaseous and liquid bodies; among the latter is sebacic acid, a 

 matter not obtained in the destructive distillation of the other oily 

 acids. 



It follows from what has been stated of the mode in which oleic 

 acid is procured, that it enters largely into the composition of soaps, 

 forming with potash soft soap, and with soda hard soap. 



The Oieatet in general are not crystallisable salts ; and those which 

 are not altogether insoluble are mucilaginous before drying ; they are 

 usually very fusible. 



Oleate of Potatlt. Tliis salt has a bitter alkaline taste. When 

 mixed with twice its weight of water, it swells and forms a trans- 

 parent jelly ; when this quantity of water is doubled, a syrupy liquor 

 is obtained. A still larger quantity of water does not render it turbid, 

 but after a considerable time a mucilaginous superoleate of potash 

 separates. Alcohol dissolves its own weight of oleate of potash, 

 when heated to 124 Fahr. and it solidifies on cooling; 100 parts of 

 boiling ether dissolve 3'43 parts, and the solution remains fluid when 

 cold. 



Bi-oleatt of Potash may also be formed ; it is soluble in water and 

 in alcohol both hot and cold, and the solution reddens litmus. 



Oleate of Soda Has a slight smell, and a slightly alkaline taste; 

 Cold water dissolves l-10th of its weight. 



Oleate of Rarijla (C M H,,BaO 4 ) is insipid, and insoluble in water. 

 Boiling alcohol dissolves only a small quantity. It is soluble in oleic 

 acid. 



Oleate of Maynuia Has the form of semi-translucent white grains, 

 which soften between the fingers. 



Oleate of Copper. This salt is green. It melts when exposed to the 

 heat of the mm. 



Oleate of Lead. The neutral oleate is prepared in the moist way. 

 It melts between 144 and 153 Fahr. Alcohol and ether dissolve it 

 slowly when cold and rapidly when hot, without altering its neu- 

 trality. 



i-olcate of Lead. This Halt is liquid at 75 Fahr., and below 

 this temperature becomes an adhesive mass. Boiling alcohol dissolves 

 a little of it, and deposits a neutral salt on cooling. Oil of turpentine 

 and oil of petroleum dissolve both it and tho neutral oleate. 



Oleate i,f M,.t/,,/l (C M H,.,(C a H 3 )0 4 ) has a specific gravity of 0-879 at 

 65" Fahr. 



Oleate of Ethyl or <Jeir rther (C M H,,(C,H,^0 4 ) is formed on passing a 

 rapid current of hydrochloric acid gas into a solution of oleic acid in 

 three times its bulk of alcohol. It is colourless, very soluble in 

 alcohol, and has a specific gravity of.0'871 at 65 Fahr. 



s // ' occurs among the products of the action of 



concentrated sulphuric acid upon olein ; cold water decomposes a part 

 of it with production of nirtnnhi<- uc'ul, and the remainder on boiling 

 is converted into "/. 



Chlorrjleic Acid (C M H, I1 C\. 1 O t ) in produced by the action of chlorine 

 n|Kiu oleic acid. It is liquid at ordinary temperatures, has a brown 

 tint and sp. gr. 1-082 at 46 Fahr. Its hulling point is 374 Fahr. 



Hromoltic acid (C M H M Br,O,) much resembles chloroleic acid. Its 

 sp. gr. is 1-272 ; boiling point 392 Fahr. 



ElnidicAcid bears the same relation to oleic acid that elaidin does to 

 olein ; it may in fact simply be considered as a solid modification of 

 oleic acid. It is produced, or rather induced, by the presence of a 

 small quantity of peroxide of nitrogen. The oleic acid operated upon 

 neither changes its composition nor its atomic weight ; a small quantity 

 is however acted upon, as traces of an oily body and of ammonia are 

 generated, and it is not improbable that these communicate molecular 

 ni' it inn to the particles of the oleic acid. 



Elaidic acid melts at about 113 Fahr. It is soluble in ether or 

 alcohol, ^and by spontaneous evaporation is deposited in beautiful 

 pearly scales resembling benzoic acid. It is volatile, and may be 

 distilled with but little alteration. Maintained at 150 Fahr. for some 



