Note O — § XXVIII. Herbs and Medicinal Plants. (Plantes Potagères et Médicinales.)

The mode of extracting the juice of plants by means of water has more or less inconvenience. All those juices which have a principle that is very volatile and easy to evaporate, lose infinitely, even in warm water; much more so therefore, when the heat of the water is raised to a higher degree, and when the plants have been left for a long time in digestion.

Aromatic vegetables are infused, when the object is to preserve the aroma, and not impart to the water the extractive principle which the plant contains. Therefore, tea and coffee are made by infusion. But all the theories ancient and modern, and all the new apparatus employed to seize and hold fast the aroma of the coffee are still very deficient.

Ebullition which is often times resorted to in order to extract the aroma of plants by means of distillation, in spite of all the apparatus made use of for keeping the same closed up, most frequently destroys the nature of the productions.

Not only are the principles extracted by the water injured by this first operation, but they scarcely retain any strength after the evaporation which it is usual to make them undergo, in order to form essences of them. The extract therefore, exhibits nothing but the appearance of the soluble and nutritive principles of vegetable and animal substances; since fire, which is necessary to form an essence by means of evaporation, destroys the aroma and almost all the properties of the substance which contains it.