VEGETABLE OILS. 147 



tutes for fat. Castor Oil, from the seeds of Ricinus coinmunis, differs 

 from other fixed oils in its composition. 



315. Decandolle gives the following table to show the quantity of 

 oils got from seeds: 



Hazel-nut 60 per cent, in weight. 



Garden Cress ...57 



Olive 50 _ 



Walnut 50 



Poppy 48 



Almond 46 



Euphorbia Lath- 



yris 41 



Colza 39 



White Mustard ..36 per cent, in weight. 



Tobacco 34 



Plum 33 



Woad 30 



Hemp 25 



Flax 22 



Sunflower 15 



Buckwheat 14 



Grapes 12 



316. Tegeiabie Wax is a peculiar fatty matter sometimes found in 

 the stem and fruit of plants. It is procured from several species of 

 Palms, as Ceroxylon andicola, and Corypha cerifera, and from the 

 fruit of Myrica cerifera or candle-berry myrtle, and Myrica cordifolia. 

 Waxy matter also occurs on the exterior of fruits, giving rise to the 

 bloom of grapes, plums, &c., on the outer surface of the bracts of Musa 

 paradisiaca, and on the leaves of many species of Encephalartos. In 

 Cork there exists a fatty body which, when acted upon by nitric acid, 

 yields suberic acid. Chlorophylle, or the green colouring matter of 

 leaves, is allied to wax in its nature, being soluble in ether and alcohol, 

 but insoluble in water. 



317. Volatile or Essential Oils occur in the stem, leaves, flowers, 

 and fruit of many odoriferous plants, and are procured by distillation 

 along with water. They are called essences, and contain the concen- 

 trated odour of the plant. They usually exist ready-formed, but 

 occasionally they are formed by a kind of fermentation, as oil of bitter 

 almonds, and oil of mustard. Some of them consist of carbon and 

 hydrogen only, as oil of turpentine, procured from various species of 

 Pinus and Abies; oil of juniper, from Juniperus communis; oil of 

 Savin, from Juniperus Sabina; oil of lemons and oranges, from the 

 rind of the fruit; and oil of neroli, from orange flowers. A second 

 series contain oxygen in addition, as oil of cinnamon, from Cinnamo- 

 mum zeylanicum; otto or attar of roses, from various species of 

 Eose, especially Rosa centifolia; oil of peppermint, from Mentha 

 viridis; oil of caraway, from Carum carui; oil of cloves, from Caryo- 

 phyllus aromaticus. Oils of this kind are procured from many Labiate, 

 as species of Lavandula, Origanum, Rosmarinus, Thymus; and from 

 the fruit of Umbellifera3, as species of Anethum, Fceniculum, Corian- 

 drurn, Cuminum, Petroselinum, Pimpinella ; and from some Compositae, 

 as species of Anthemis, Pyrethrum, and Artemisia. A third series have 

 also sulphur in their composition, and have a peculiar pungent, often 

 alliaceous smell, with an acrid burning taste, as oil of garlic, and of 

 onion, procured from the bulbs of Alhum sativum and Cepa; oil of 



