ECONOMIC BOTANY. 121 



4. Caoutchouc has become, since the invention of the pro- 

 cess of vulcanizing (impregnating with sulphur) a very im- 

 portant article, and is now used for a great variety of pur- 

 poses. It occurs in the form of granules in the milky juice 

 of many plants, as Siphonia (Spurge family), in Brazil ; Urce- 

 ola (Dogbane family), in East India ; Vahea (Dogbane family), 

 in Madagascar. Caoutchouc is a "non-conductor" of elec- 

 tricity, insoluble in water, not attacked by acids at ordinary 

 temperatures, swells up in alcohol, oil of turpentine, carbon 

 bisulphide, ether and benzine. Ebonite is harder, containing 

 more sulphur. Gutta percha is not so widely distributed as 

 Caoutchouc. It occurs in the milky juice of plants only of 

 the family SapotaceBe. Most of it is furnished by Isonandra 

 gvMa, a tree of India and the Sandwich Islands. It is not so 

 elastic as Caoutchouc, but much like the latter, though more 

 complex in composition. Gutta percha is used in immense 

 quantities to cover submarine cables. 



5. Opium is the dried milky juice from the sliced pods of 

 the White Poppy (Papaver somiiiferuTn). The plant is culti- 

 vated extensively in Egypt, Asia Minor, Persia and India. 

 Opium contains several alkaloids, the most important being 

 morphine, papaverine, and narcotine. The inspissated juice from 

 the leaves of several species of the genus Aloe (Iris family), 

 especially A. vulgaris and A. socotrina, constitute the drug 

 Aloes, used in medicine and dyeing. The plants grow in 

 Africa; they have thick fleshy leaves and tall flowering 

 spikes. Palm oil is expressed from the fruits of Eleeis guine- 

 ensis (Palm family) a small tree growing in Africa, the West 

 Indies and Brazil. It is extensively used in the manufacture 

 of candles and soap, and in lubricating machinery. The na- 

 tives of the countries where this Palm grows use the oil for 

 food. The Olive, Olea europsea, a small evergreen tree of the 

 Ash family, cultivated extensively in the Mediterranean re- 

 gion, produces dark violet or black drupes from which Olive 

 oil is obtained. Another important oil is expressed from flax- 

 seed, usually called Linseed oil. It is a drying oil, used in 

 the manufacture of printers' ink, varnishes, soaps, etc. 



L 



