A dispensatory, or commentary on the pharmacopoeias of Great Britain (and the United States) comprising the natural history, description, chemistry, pharmacy, actions, uses, and doses of the articles of the materia medica / [Sir Robert Christison].

  • Robert Christison
Date:
1848
Catalogue details

Licence: Public Domain Mark

Credit: A dispensatory, or commentary on the pharmacopoeias of Great Britain (and the United States) comprising the natural history, description, chemistry, pharmacy, actions, uses, and doses of the articles of the materia medica / [Sir Robert Christison]. Source: Wellcome Collection.

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    GeneraL Directions, Edin. Distilled wa- ters may be -prepared from fresh, and generally also from dried vegetables. In the latter case only half the weight of material should be used. They may also be prepared for the most part by agitating the volatile oils of plants with water and filtering the solution. But distilled waters obtained in this way have seldom so fine a flavour as those obtained from plants them- selves. any vegetable matter add half an ounce of rectified spirit. ’ DisTILLED waTERs consist of the volatile oils of odoriferous vegetables dis- solved in water. ‘They are generally obtained by distilling water from crude vegetable substances; but they may be often conveniently made by agitating water with the volatile oil obtained previously, and kept in store for the pur- pose, or by distilling the water and oil together. Fine distilled waters may be made by simple agitation of volatile oils with water, provided the oils be recent, and skilfully prepared. But if the oils have been long kept, they be- come in part oxidated by absorption of oxygen from the air; and it is found that distilled waters of rich fragrancy cannot be prepared from volatile oils of this kind. [In the case of most of the aromatic waters, the United States Pharmacopeia directs the impregnation of the water by the appropriate volatile oil, aided by trituration with carbonate of magnesia; the medicated fluid to be then filtered. The use of the magnesia is merely to enable the ope- rator to produce such a state of extreme division of the oil, as will enable the water to act with more efficiency upon it. Other powders act in the same manner, as that of prepared chalk, &c.] Hence, for the most part, the crude vegetable substances themselves are preferred, when they can be had. Many of these substances lose their volatile oil and fragrance when dried, and must consequently be used in the fresh state. But in some instances—most of which are specified by the Pharmacopwias—the oil is retained, notwithstand- ing desiccation, so that the dried plant is available for the purpose of the dis- tiller. Many vegetables which lose their fragrance when dried, retain it in perfection for years, when preserved by being beat into a pulp with salt, and may be used in this state for making excellent distilled waters. Even rose- water may be thus made of fine quality. Heat may often be applied directly to the vessel; but in this way empy- reuma is apt to be occasioned, especially in large operations, in consequence of the solid matters remaining fixed at the bottom. ‘T'o avoid this, it is usual to apply the heat, in limited operations, through the medium of a solution of hydrochlorate of lime, which raises a temperattre between 212° and 270°, according to its strength,—or by means of an oil-bath with a thermometer to regulate the temperature; and on the great scale, it is applied best of all by means of steam admitted under pressure into a space surrounding the still.— Another cause of the empyreumatic taint of some distilled waters is the forma- tion of a species of mucilaginous substance at the expense of the volatile oil (Brendecke). ‘This substance, which forms chiefly when the distillation is pushed teo fast, or too far, and is seen encrusting globules of volatile oil un- dissolved in the water, is apt to deposit itself on the side of the still, above the boiling materials ; where it is afterwards decomposed by the heat. This - fact explains the well-known observation, that the finest distilled waters are obtained by gentle distillation, and by abstaining from complete exhaustion of the materials. A still greater improvement is to prepare them with the vacuum-still, in the same way as is now often practised in making extracts.— Liebig’s refrigeratory (p. vii.) is here again the best contrivance for condensing the vapour. The material which supplies the volatile oil is in general simply mixed with the water in a state of fine division; and this is probably the best mode
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