420 OLEACE^. 



C^^H^'O^, from olive oil; and Heintz and Kriig (1857) further proved 

 that Tripalmitin is the chief of the solid constituents of olive oil. They 

 also met with an acid melting at 7l'''4 C, which they regarded as 

 AracJdc Acid (p. 187). As to stearic acid, Heintz and Krug did not 

 fully succeed in evidencing its presence in olive oil. 



Lastly, Benecke discovered in olive oil a small quantity of Choks' 

 teHn, C"^'H"*^0. It may be removed by means of glacial acetic acid or 

 alcohol, which dissolve but very little of the oil. 



Commerce — Various sorts of olive oil are distinguished in the 

 English market, as Florence, Gallipoli, Gioja, Spanish (Malaga and 

 Seville), Sicily, Myteline, Corfu and Mogador. 



Olive oil was imported into the United Kingdom in the year 1872 

 to the value of £1,193,064. Nearly half the quantity was shipped from 

 Italy, one-fifth from Spain^ and the remainder from other Mediterranean 

 countries. 



The average annual production in Italy is estimated at ahout 3 

 millions of hectolitres {66 million gallons), but the quantity exported 

 docs not reach half that amount. 



The statistics of the French Government indicate the annual pro- 

 duction of olive oil in France to be not more than 250,000 hectolitres, 

 equivalent in value to 30 millions of francs (£1,200,000).^ 



Uses — The uses of olive oil in medicine and its immense consump- 

 tion in the warmer parts of Europe as an article of food, are too well 

 known to require more than a passing allusion. 



Adulteration— Olive Oil is the subject of various fraudulent 

 admixtures with less costly oils, the means of detecting which has 

 engaged much attention. Of the various methods by which chemists 

 have endeavoured to ascertain the purity of olive oil, the foUowmg are 

 the more noteworthy : — 



a. Drying' oils (such as the oils of poppy and walnut) way be 

 distinguished by their not being converted into solid crystallizable 

 elaidin by hyponitric acid or concentrated solution of nitrate ot 

 protoxide of mercury. Olive oil which contains any considerable 

 proportion of one of these oils, no longer solidifies if exposed for a 

 moment to one of the above-mentioned reagents. This test however 

 IS not of sufficient delicacy for small amounts of drying oils. 



b. Olive oil being one of the lighter oils, the specific gravity 

 may to some degree indicate admixture with a heavier oil. i 

 make use of this fact, Gobley and other chemists have inventeQ 

 an instrument called an elaiometer, for taking the specific gravity 

 of oils, 



c. Observation of the Cohesion-figure.— This test, proposed l)y 

 Tomhnson in 1SG4,2 depends on the forces of cohesion, adhesion, 

 and diffusion. Thus, if a drop of any oil hanging from the end oi '^ 

 glass rod is gently deposited upon the surftxce of chemically ciea 

 water, contained in a clean glass, a contest takes place between m 



J^ry International, xi. 108. -In the work 



400,000 hectolitres are calculated or 



of r.„+r "'• ,""'• ^"»-— ill the work year 1SG6. , „„„ iO') with 



of Coutance, quoted p. 417, note 7, nearly ^ ^ p/,„^. Journ, y. (1864) 38/. 49... 



fig area. 



