184 On the Classification of Poisons, [Sept. 



ever render its degree of perfection progressive with the ad- 

 vancement of science. In the next place, the classes are in 

 xnanv particulars ill-defined, and indistinctly, if not erroneously, 

 divided. How questionable, for instance, are the boundaries 

 which separate corrosive from acrid poisons ? even the respect- 

 ive species of each class are, in many instances, less allied to 

 each other than the great divisions to which they are subordi- 

 nate. As an exemplification of this fact we have only to com- 

 pare the physiological actions of arsenic and corrosive sublimate; 

 the former of these substances 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 comes in 

 contact. In the same manner, if we examine the individual 

 actions of the different species composing the class of " Acrid " 

 poisons, we shall find the same want of uniformity ; thus the 

 spurge-flax, and the jatropa 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 more 

 absolute in its definition, and more uniform in its physiological 

 affinities, and therefore less objectionable, than the d.i visions to 

 which we have just alluded; but the propriety of the term 

 " Narcotico- Acrid " may be very reasonably questioned ; even 

 Orfila expresses his doubts upon the subject, " because the 

 narcotic or sedative effects only follow the previous excitement.'' 

 Some of the poisons, under this last mentioned class, are 

 rapidly absorbed, and act, through the medium of the circulation, 

 on the nervous system, without producing any local inflamma- 

 tion ; whilst others, again, 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 adduced, are 

 sufficient to demonstrate the imperfection of the classification 

 under consideration, and which would render it wholly unavail- 

 able to the pathologist who must adopt his treatment according 

 to the physiological action of each poison. The author has 

 accordingly, in his " Pharmacologia,'' ventured to propose an 

 arrangement, in conformity with such views ; and the following 

 sketch of it may perhaps form a useful introduction to the gene- 

 ral observations which it will be hereafter necessary to offer upon 

 the " modus operandi " of poisons. 



