Volume 5

The elements of materia medica. Comprehending the natural history, preparation, properties, composition, effects and uses of medicines / [Jonathan Pereira].

  • Pereira, Jonathan, 1804-1853.
Date:
1839-1840
Catalogue details

Licence: Public Domain Mark

Credit: The elements of materia medica. Comprehending the natural history, preparation, properties, composition, effects and uses of medicines / [Jonathan Pereira]. Source: Wellcome Collection.

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    cannot be referred to the latter. We therefore ascribe them to their specific impressions on the nerves of the part to which they are applied. The effects of the substances composing this group are very quickly produced, and soon disappear. Consequently these remedies are adapted to urgent and acute cases, when the danger is imminent, and an immediate ~ effect desired: for the same reason they require to be frequently repeated in order to keep up their effects. From their exciting opera- tion they are indicated in cases of debility and sinking of the vital powers. ‘Thus they are employed in syncope, low fevers, cholera, &c. On account of their specific influence over the nervous system they are — administered in various spasmodic or convulsive diseases, especially in hysteria, and also in epilepsy and chorea. | J. The sixth group contains camphor, the roots of serpentary, con- trajerva, and valerian, the oil of cajuputi, &c. It corresponds with that division of volatile excitants called by Vogt, etherio-oleosa ; it is a less perfect group than any of those already mentioned. ‘To a certain extent it agrees in its effects with the last mentioned: thus it specifically stimulates the nervous system, increases the activity of the vascular system, and produces diaphoresis. Its effects, however, are much less powerful, are not so speedily produced, nor are they so fleeting. Some of the substances of this group (for example, serpentary and contrajerva) are serviceable in low nervous fevers; others are used in spasmodic diseases, as valerian in epilepsy. g. The seventh and last group is the spirituosa of Vogt. It compre- hends those substances already mentioned under the head of cerebro- Spinants, as inebriating; namely, alcohol, wine, and ether. Their effects and uses will be fully described in a subsequent part of this work. Active principles.—Volatile oil and resin are the most common con- stituents of the foregoing groups. 1. Volatile oil (oleum volatile, vel athereum, seu essentiale).—V olatile oil is found in both the inorganised and organised kingdoms of nature : it is most common in vegetables. Petroleum and naphtha are examples of volatile oil in the mineral kingdom. Among animal substances castoreum ma be referred to as containing it. It is found in various parts of vegetables — as in the cortical parts of their stems, in cinnamon and cassia; in their rhizomes, as in ginger and Acorus Calamus; in the root, as in valerian and horse-radish ; in the leaves, as in buchu, Ladbiate, and Myrtacee; in buds, as in the bulbs of garlic and onions; in fruits, as the orange and Umbellifere; and sometimes, though very rarely, in the seeds, as in the nutmeg. From these different parts it is occasionally obtained by pres- sure, but more commonly by distillation. The volatile oils may be solid or liquid at ordinary temperatures ; when solid they are crystalline. They may be lighter or heavier than water; their sp. gr. varying from 0°627 to 1:094 (Gmelin). They may be coloured or colourless ; if the former, the tint is various in different oils. All the essential oils have a strong odour, and a hot acrid taste. They are easily volatilised by heat; are combustible, in consequence of .the large quantity of carbon and hydrogen which they contain; and are decomposed by chlorine, iodine, bromine, and the acids. Some of them (as the oil of turpentine) combine with hydrochloric acid. They are very ~