ESSENCES ALBUMEN. 171 



The cruciferous plants we have described, such as horse-radish, mus- 

 tard, water-cress, &c., owe their pungency to their acrid volatile oil. 

 These are termed siliquose condiments. So also with the aliaceous 

 condiments we have mentioned, such as garlic, onion, leeks, &c. ; like- 

 wise the spices, as the nutmeg, cinnamon, cloves, peppers, allspice. 

 The leaves of the peach, laurel, and many others, contain this oil. 

 The volatile oils are much adulterated, as sold from the shops, with 

 resinous substances, fixed, and inferior oils and alcohol. The two 

 first are detected by distillation, and the last by agitating the oil in 

 water, when it becomes milky. 



Essences are prepared from the volatile oils by dissolving 1 part of 

 them in 8 of spirits of wine. It is not known that the effects of these 

 oils, as combined with the above substances, serve any other pur- 

 pose than the gratification of taste ; yet it is but reasonable to con- 

 clude that they do. They are thrown out of the system, after absorp- 

 tion, in the secretories, possessed of all these peculiar qualities. 

 They are evidently stimulating ; and it may be their chief office thus 

 to promote the action of the fluids and solids, and quicken their 

 action. They may produce heat by being burned in the lungs. It 

 cannot be doubted that they exert an important influence in the ani- 

 mal functions. 



Albuminous substances. These, with fibrine and caseine, are de- 

 nominated proteinaceous aliments, or the albuminous principle. Pro- 

 teine is composed, per centum, of carbon 55.44, hydrogen 6.95, nitro- 

 gen 16.05, oxygen 21.56, in 100 parrs. It exists in organic bodies with 

 sulphur, phosphorus, potash, soda, common salt, &c. The compounds 

 of protiene form the elements of nutrition ; and these are produced by 

 vegetables alone, though the power of converting one modification of 

 protiene into another is possessed by animals. In this point of view, 

 says Liebig, the vegetable forms of proteine ; vegetable fibrine, albu- 

 men and caseine become signally important as the only source of pro- 

 teine for animal life, and consequently, of nutrition, or the growth in 

 mass of the animal body." These vegetable proteinaceous principles, 

 though, as we have before said, identical with those of animais, are 

 distinguished as vegetable fibrine, albumen, caseine and pure gluten. ^ 

 How beautiful and admirably simple," says this author, appear 

 the processes of nutrition and the formation of the organs of animals 

 in which vitality chiefly resides ! Those vegetable principles, which 

 in animals are used to form blood, contain the chief constituents of 

 blood, fibrine and albumen, ready formed. All plants, besides, con- 

 tain a quantity of iron, which reappears in the coloring matter of the 

 blood. Vegetables produce, in their organism, the blood of all animals ; 

 for the carnivora, in consuming the blood and flesh of the graminivora, 

 consume, strictly speaking, only the vegetable principles which have 

 served for the nutrition of the latter. 



