The London dispensatory, containing: I, the elements of pharmacy; II, the botanical description ... and medicinal properties, of the substances of the materia medica; III, the pharmaceutical preparations and compositions of the pharmacopoeias of the London, Edinburgh, and Dublin Colleges of Physicians / By Anthony Todd Thomson.

  • Thomson, Anthony Todd, 1778-1849.
Date:
1830
Catalogue details

Licence: Public Domain Mark

Credit: The London dispensatory, containing: I, the elements of pharmacy; II, the botanical description ... and medicinal properties, of the substances of the materia medica; III, the pharmaceutical preparations and compositions of the pharmacopoeias of the London, Edinburgh, and Dublin Colleges of Physicians / By Anthony Todd Thomson. Source: Wellcome Collection.

    34/1096 (page 14)
    IJ. REPULSION. Reputsron is that force which separates the particles of bodies from one another, and consequently counteracts or modi- fies the attractions by which they are combined and preserved together in masses. It is supposed to depend on the operation of one or more of the three following powers: Caloric, Light, Electricity. a. CALORIC. The cause of the sensation of heat is denominated Caloric. Philosophers are not completely agreed whether it is a pro-~ perty only of bodies, such as a vibration of their particles, * or a peculiar substance; but the latter opinion is the one more generally adopted. Under this opinion, caloric is regarded as a very subtile, elastic fluid, which penetrates more or less all bodies, passing readily from one to another, and is every where diffused. Its particles are supposed mutually to repel each other; and bodies into which it enters in any sensible quantity are increased in bulk, and undergo other changes of form, while their density is diminished. It is radiated in the same manner as light, and in this state forms a part of the solar ray.” ‘The rays are re- frangible, and capable of reflection, and of polarization, like those of light. It has no ascertainable gravity; and neither the addition nor the abstraction of it alters sensibly the weight of bodies.* It exists in two different states: in a free state, in which it is merely loosely mingled, as it were, with other bodies ; and, in a latent state, or one of intimate combination. Regarding it as matter, the sources whence it may be ob- tained, the laws which regulate its motion and distribution, and its effects, require to be noticed. Sources of Caloric. The known sources of caloric are the sun, combustion, per- cussion, friction, and mixture. a. ‘The sun is an apparent source of caloric; but the direct action of the sun’s rays upon bodies seldom produces a tem- perature exceeding 160°. When these, however, are concen- trated by means of a concave mirror, or a lens; or when means are taken to prevent the communicated heat from being car- ried off by the surrounding bodies, a much higher temperature can be produced. ‘This source of caloric is not resorted to for pharmaceutical purposes. 6. Combustion is a source of caloric highly interesting on account of its utility. When a combustible is heated to a certain degree, it be- lia ne ce ' The idea of caloric being motion or vibration originated with Lord Bacon. ® Philosophical Trans. 1807. 3 Jb. 1799. p. 179.