Mr. Wharton Jones, in his Astley Cooper Prize Essay, states that he has found the effects of medicinal solutions on the capillaries in the web of a frog's foot to be very various. For even a solution of Sulphate of Copper has been known to cause dilatation, and one of Atropia to produce constriction; though the former is an astringent; and the latter a paralyzer. So that the vessels are not nearly so much under the influence of such agencies as Dr. Billing would seem to imagine. In these experiments the solutions were concentrated, and applied directly. But in the cases in point we might have two or three grains of Iodide of Potassium, one-tenth of a grain of Arsenite of Potash, or one-twentieth of a grain of Bichloride of Mercury, diluted down by about twenty pounds of blood, and extended through many miles of capillary tubes! And if simple contraction of the capillaries were required, surely Astringents, which are known to effect this, should be the most useful of all these medicines. But we do not find it to be so. Further, this idea must include a virtual denial of the causation of blood disorders by special morbid agencies. Such are the grounds upon which is founded a denial of the existence of specific medicines--_i.e._ of remedies which are of particular or special use in one or more disorders. Is it reasonable to deny that Mercury is of particular use in Syphilis? that Iodide of Potassium exerts a special influence over secondary forms of the same malady? that Iodine and Potash are each peculiarly adapted to scrofulous cases? or that Colchicum will often stop a fit of the Gout when other medicines have failed to relieve it? If we cannot deny it, we must admit such actions to be in some degree specific. To adopt this term is to a certain extent to confess our ignorance, and for this reason many have objected to it; but this we cannot avoid. The word is, however, decidedly objectionable, when it is misapplied to express the idea of some particular medicine being the only one that can be used in a certain disorder. For this is an exaggeration of the truth that may lead to very serious error. Before now proceeding to the proof of the minor propositions of Catalytics taken collectively, I must enumerate the chief remedies which I intend to include in the eight separate orders into which this division of blood-medicines has been divided. _Ord. 1. Antiphlogistics._ Antimonials; Mercurials; Alkalies; Salines.