Salines have been shown by Mr. Gulliver to have the effect of keeping the blood-corpuscles apart from one another. This may partly explain their action; for in inflammatory blood the corpuscles display a peculiar and abnormal tendency to aggregate together in rows. Salines also are solvents of Fibrine. The immediate action of Mercury in checking inflammation is often very apparent in the case of Iritis. This medicine in some way diminishes the plasticity of the Fibrine of the blood; and probably promotes absorption by preventing in this way a further deposit of lymph. If the blood be analyzed after the continued use of Mercury, it is found to contain less Fibrine than in health. It has also a peculiar action of its own in the blood, for it sometimes produces various eruptions, particularly Eczema, as well as a state called Mercurial fever. Antimony has various and marked medicinal properties: in large doses Neurotic; in all cases Eliminative. But we are now concerned merely with an agency in the blood. It has certainly some action of this kind. When rubbed on the skin it produces a pustular eruption; and M. Lepelletier gives a case in which it did this when administered only internally. Magendie found that when given to dogs it produced engorgement, and often inflammation of the lungs. Antimony seems to exert a blood-influence over inflammation somewhat similar to that of Mercury; but it further adds to this a powerful sedative effect. Antimony generally arrests inflammation by reducing the pulse; but Mercury reduces the pulse by arresting inflammation. Thus do Antiphlogistics exert that operation in the blood which is essential to Catalytic medicines. The divisions of Hæmatics differ in this: Restoratives act by being in the blood; Catalytics by working in the blood. All we have to prove of the latter just now is to establish this part of their action. _Antisyphilitics_ have also this action. Mention has already been made of the hæmatic effects of Mercurials. The action of the compounds of Gold is similar, though these are not now often employed. But as far back as the commencement of the eighteenth century the administration of Gold in syphilis was strongly recommended by Dr. A. Pitcairn. He employed the pure metal in a fine state of division. He also made use of a mercurial which resembled our modern blue-pill, but must have been considerably less potent, for it was given in drachm doses. Iodide of Potassium may be said to combine the actions of Iodine and of Potash. This medicine is very active in causing the absorption of syphilitic nodes. Its use is sometimes followed by a slight cutaneous eruption. Sarsaparilla is supposed by many to exert an alterative action in the blood; but this is not very clear, nor is its utility often very decided.