§ 17. At some future time, with a more intimate knowledge of the way in which each poison acts upon the various forms of animal and vegetable life, it may be possible to give a truly scientific and philosophical classification of poisons--one based neither upon symptoms, upon local effects, nor upon chemical structure, but upon a collation and comparison of all the properties of a poison, whether chemical, physical, or physiological. No perfect systematic arrangement is at present attainable: we are either compelled to omit all classification, or else to arrange poisons with a view to practical utility merely. From the latter point of view, an arrangement simply according to the most prominent symptoms is a good one, and, without doubt, an assistance to the medical man summoned in haste to a case of real or suspected poisoning. Indeed, under such circumstances, a scheme somewhat similar to the following, probably occurs to every one versed in toxicology:-- A. POISONS CAUSING DEATH IMMEDIATELY, OR IN A FEW MINUTES. There are but few poisons which destroy life in a few minutes. Omitting the strong mineral acids, carbon monoxide, carbon dioxide, with the irrespirable gases,--_Prussic acid_, _the cyanides_, _oxalic acid_, and occasionally _strychnine_, are the chief poisons coming under this head. B. IRRITANT POISONS (symptoms mainly pain, vomiting, and purging). _Arsenic_, _antimony_, _phosphorus_, _cantharides_, _savin_, _ergot_, _digitalis_, _colchicum_, _zinc_, _mercury_, _lead_, _copper_, _silver_, _iron_, _baryta_, _chrome_, _yew_, _laburnum_, _and putrid animal substances._ C. IRRITANT AND NARCOTIC POISONS (symptoms those of an irritant nature, with the addition of more or less pronounced cerebral indications). To this class more especially belong _oxalic acid_ and _the oxalates_, with several poisons belonging to the purely narcotic class, but which produce occasionally irritant effects. D. POISONS MORE ESPECIALLY AFFECTING THE NERVOUS SYSTEM. 1. NARCOTICS (chief symptom insensibility, which may be preceded by more or less cerebral excitement): _Opium_, _Chloral_, _Chloroform_. 2. DELIRIANTS (delirium for the most part a prominent symptom): _Belladonna_, _hyoscyamus_, _stramonium_, _with others of the Solanaceæ_, to which may be added--_poisonous fungi_, _Indian hemp_, _lolium temulentum_, _œnanthe crocata_, and _camphor_. 3. CONVULSIVES.--Almost every poison has been known to produce convulsive effects, but the only true convulsive poisons are the _alkaloids of the strychnos class_. 4. COMPLEX NERVOUS PHENOMENA: _Aconite_, _digitalis_, _hemlock_, _calabar bean_, _tobacco_, _lobelia inflata_, and _curara_. * * * * * § 18. KOBERT’S CLASSIFICATION.--The latest authority on poisons--Kobert--has classified poisons according to the following scheme:-- I. POISONS WHICH CAUSE COARSE ANATOMICAL CHANGES OF THE ORGANS. A. Those which specially irritate the part to which they are applied.