Some have supposed that Nitrate of Silver cures Epilepsy by diminishing an irritable condition of the stomach. But it is observed by Dr. Pereira that the existence of this irritability in all cases of Epilepsy is a mere assumption. The solution of this salt exerts, according to its strength, an astringent or caustic action on all mucous surfaces, and thus improves their condition when they are relaxed, inflamed, irritable, or ulcerated. The occasional benefit which follows the administration of the preparations of Silver in Gastrodynia may be referred to an action of this kind. The action of Arsenic in some intermittent varieties of this painful affection has already been mentioned, and is explained in another way. Caustic substances probably act locally in these cases; but Arsenious preparations exert an Antiperiodic influence in the blood generally. Tetanus is by far the most incurable of these convulsive disorders. Arsenic and other medicines of this order have been recommended in the treatment; but although some cases appear to be partly connected in their first origin with a certain condition of the blood, this disease is very little under the influence of blood medicines, or indeed of any medicines at all. ORD. VIII. ANTISQUAMICS. Skin diseases are both caused and cured in a variety of ways. Some are produced by external influences. They may be brought on by mere irritation, as certain kinds of Eczema and Herpes, and are then to be treated with soothing unguents or cool lotions. Or they may even be connected with some external organization, of a vegetable or animal kind, as Porrigo and Favus are traceable to a parasitic fungus, and Scabies is accompanied by the development of a species of Acarus. Others are due to some wrong in the digestive process, or to a plethoric condition of the system. Urticaria is an example of the former, Acne of the latter. They may generally be treated most effectually by the exhibition of salines and rhubarb. A third class of skin diseases are due to the existence in the blood of certain poisons or peculiar morbid conditions. The eruption may constitute one only among many symptoms of the action of this poison, or it may be the chief or only symptom. The former is the case in Syphilis and the Eruptive fevers. It is with the latter kind that we are now concerned. There are two modes by which we may get rid of the poison that causes the eruption--Elimination and Counteraction. The first may sometimes be effected by the use of Purgatives, Sudorifics, or Diuretics. But I have classed in this last order of Catalytic blood-medicines some remedies that have proved useful in counteracting the causes of these diseases. The eruptive disorders alluded to are all connected together both in their symptoms and treatment; but because the squamous diseases, Lepra and Psoriasis, are the most characteristically under the influence of these remedies, the latter have been named Antisquamics.