IRRITANTS { Acid poisons--Sulphuric acid, &c. _Mineral_ { Alkaline poisons--Caustic soda, &c. { Non-metallic--Phosphorus, Iodine, &c. { Metallic--Arsenic, Antimony, &c. _Vegetable_--Savin, Elaterium, &c. _Animal_--Cantharides. NEUROTICS _Cerebral_--Opium, Hydrocyanic acid, Alcohol. _Spinal_--Strychnia, Nux vomica. _Cerebro-spinal_--Conium, Belladonna, Aconite. _Cerebro-cardiac_--Calabar bean, Digitalis. (Taylor.) The subjoined classification is based upon that adopted by the late Professor Sir Douglas Maclagan. Where the poison acts in such a manner as to place it in two or more groups, I have fully described it in one, merely drawing attention to it under the others: DIVISION I CHEMICAL { Acids. _Corrosive_, { Alkalies. { Caustic salts. _Vulnerant_, Glass, Needles. DIVISION II VITAL _Irritant_, Metalloid, Phosphorus, Iodine. “ Metallic, Arsenic, Antimony, Mercury, &c. “ Vegetable, Gamboge, Elaterium, Colchicum, Squill. “ Animal, Cantharides, Ptomaines. _Narcotic_, Somniferous, Opium. “ Deliriant, Hyoscyamus, Belladonna. “ Inebriant, Alcohol, Cocculus Indicus, Chloroform, Ether, Cannabis Indica. _Sedative_, Cardiac, Digitalis, Aconite, &c. “ Cerebral, Ether, Chloroform, Hydrocyanic acid. “ Neural, Conium, Aconite. _Excitomotory_, Strychnia, Ergot. _Irrespirable Gases_, Carbonic acid, Carbon monoxide, Coal gas, Chlorine. _Toxicohæmic or Septic_, Snake venom, Ptomaines, “Toxins.” =Action of Poisons.=--Amid the difficulties which surround this subject, three points appear to have been clearly made out: (1) That it is necessary for all poisons to enter the blood before their specific action can be produced. (2) That poisons possess an elective affinity for certain tissues and organs. Thus, arsenic, however introduced into the system, as a rule attacks the stomach; and this peculiarity of action closely allies it to the poisons of typhoid, scarlet fever, smallpox, &c., which appear to have, respectively, an elective affinity for the glands of the intestines, the throat, and the skin. (3) That the habitual use of a poison in medicinal doses does not ensure a perfect toleration on the part of the system with regard to the action of the poison, for sooner or later a complete cachexia is produced, showing that the poisonous effect of the drug is not arrested.