132. ADDITIONAL NOTES. 



known only by the effect, which it produces ; 

 and, these things being considered, it seems to 

 be not contrary to what analogy would lead us 

 to expect, that in like manner as the electric 

 force, generated by chemical decomposition at 

 one end of a metallic wire, directs the needle of a 

 telegraph, or causes the explosion of gunpowder, 

 at the other extremity, so a substance, such as 

 the hydrocyanic acid, which powerfully affects 

 the vital properties of the part to which it is 

 applied, should be capable, through the medium 

 of the nerves, of disturbing, and even of arrest- 

 ing, the functions of the brain. 



I would not, however, be understood as affirm- 

 ing that the facts which I have now stated, or 

 the suggestions which I have offered, are to be 

 regarded as conclusive. Further observations 

 may be required before the question is finally 

 determined. In the meanwhile, in this as in 

 numerous other instances, (which occur not much 

 less frequently in the strict pursuits of science 

 than in the common affairs of life,) some indi- 

 viduals will be inclined to one opinion, and 

 others to another, accordingly as one or another 

 order of facts may more especially have engaged 

 their attention. 



As connected with this subject, I may take the 

 opportunity of noticing a circumstance which 

 came under my observation as long ago as the 

 year 1809, and which seems to show that the 

 influence of certain poisons admits of being pro- 

 pagated to distant parts by the mere continuity 



