Thomson's Conspectus of the British pharmacopoeias.

  • Thomson, Anthony Todd, 1778-1849.
Date:
1852
Catalogue details

Licence: Public Domain Mark

Credit: Thomson's Conspectus of the British pharmacopoeias. Source: Wellcome Collection.

    18/248 (page 14)
    carbonic acid, loses its solubility, and forms a pellicle of carbo- nate of lime on the surface of the water, till the whole of the lime is abstracted. The Neutral Earthy Salts do not require any particu- lar care or management, except that they ought not to enter into extemporaneous prescriptions with substances which are likely to decompose them; or with those acids with which they form insoluble compounds; as, for example, chalk with sulphuric acid. METALS, AND THEIR SALTS. Metals, which are supposed to be simple substances, have, with a few exceptions, a greater specific gravity than any other class of bodies; they are dense, opaque, susceptible of a fine polish, tenacious; and are the best conductors of heat. They are more or less fusible, and may be volatilized by heat. In their metallic state they have affinities for each other, and also for oxygen, hydrogen, carbon, sulphur, phosphorus, chlorine, iodine, and bromine; and when united with oxygen, form acids, alkalies, and the earths. None of the metals, except tin, are employed in the metallic form as remedies in the practice of medicine; but for pharma- ceutical purposes it is of importance to obtain them in as pure a state as possible. Metals, united with simple substances, form compounds, which are named from the base; for example, chlorides, sulphurets, phosphurets, iodides, bromides, oxides. Metallic Salts are either simple combinations of the metals with oxygen, or combinations of their oxides with acids. Metals combine with various portions of oxygen, which are denoted and expressed by the colour of the oxides, as grey oxide of mercury, red oxide of mercury, 8fc. Oxides have not the lustre, opacity, tenacity, nor gravity of the metals; they are uninflammable, generally insipid, nearly insoluble in water, and have an earthy appearance. They require to be kept in stopped bottles, as some of them are reduced by hydrogen, which is more or less constantly floating in the atmosphere. The metallic salts, which, properly speaking, are oxides com- bined with the acids, are of a saline nature, generally soluble in water, and crystallizable. They are named from the acid, and the metal with the oxide of which it is combined, as sulphate of iron, nitrate of silver, fyc, meaning sulphate of the oxide of iron, 8fc. The active properties of metallic salts vary much, according to the degree of previous oxidizement of the metals they contain; thus the same acid, united with an imperfect oxide, will form an insipid, insoluble compound, while, with a more perfect oxide, the compound will be acrid, and soluble in water.