_Corrosive_ from _Acrid_ poisons? the respective species, even, of each class are, in many cases, less allied to each other, than are the great divisions to which they are subordinate. As an exemplification of this fact we have only to compare the physiological actions of _Arsenic_ and _Corrosive Sublimate_, both of which are arranged under the class of Corrosive Poisons. The former of these substances undoubtedly occasions death by being absorbed, and thus acting as a vital agent; the latter, by its local action, as a caustic on the textures with which it immediately comes into contact. In the same manner, if we examine the individual actions of the different species composing the class of “_Acrid_ Poisons,” we shall discover the same want of uniformity; thus, the _Spurge Flax_, and the _Iatropa Curcas_, act by occasioning a local inflammation, while the _Hellebore_, being rapidly absorbed, exerts a fatal action on the nervous system, and produces only a very slight inflammation. The class of Narcotic Poisons is certainly more absolute in its definition, and more uniform in its physiological affinities, and therefore less objectionable than the divisions to which we have just alluded; but the propriety of the class “_Narcotico-Acrid_” is by no means equally unexceptionable; indeed Orfila himself questions it, “because the narcotic or sedative effects only follow the previous excitement.” Some of the poisons of this division also are rapidly absorbed, and act, through the medium of the circulation, on the nervous system, without producing any local inflammation; while others, on the contrary, merely act upon the extremities of the nerves, with which they come in contact, and, without being absorbed, occasion death by a species of sympathetic action. These few objections, and many more might be urged, are sufficient to demonstrate the imperfection of the classification under consideration, and which must render it wholly unavailable to the physician in the treatment of cases of poisoning, who must derive his plan of cure from the physiological action of the substance against which he has to contend; thus, for instance, _Arsenic_ and _Corrosive Sublimate_ are both corrosive poisons, but so materially do they differ from each other in their physiological actions that, when swallowed, they will require for the preservation of the individual, a very different system of treatment. For such reasons I have ventured to propose a new arrangement of Poisons, which may furnish the practitioner with a general theorem for the administration of Antidotes. A SYNOPTICAL TABLE OF POISONS, NEWLY ARRANGED ACCORDING TO THE DIFFERENT PRIMARY OPERATIONS, BY WHICH THEY PRODUCE THEIR EFFECTS, With a view to furnish a General Theorem for the administration of Antidotes.