INTRODUCTION 29 



green, nitric acid and picric acid a yellow colour. The 

 blue (indigo, ultramarine, or Prussian blue) or black (soot) 

 pigments of vermin powders are rarely detectable, because 

 of the small quantity of the poison ingested. 



CHEMICAL ANALYSIS. 



Some details as to chemical toxicology are reserved to a 

 later treatment in this volume. At this place, however, 

 a few points of value to the clinician and chemist may be 

 indicated. The analyst is at the mercy of the pathologist, 

 who has it in his hands to render an analysis decisive, for 

 or against, or to nullify the value of a laborious search. 



The foUotving suggestions are therefore made : 



1. General details of the symptoms should be given, and 

 particular note of the drugs administered in treatment. In 

 a stomach the analyst may find a trace of an active drug, 

 such as strychnine. Without knowledge of the treatment, 

 he is confronted with the problem, Is this a residue of an 

 original poisonous dose, or is it an unabsorbed fraction 

 of a legitimate medicinal dose ? With nothing before him 

 save a jar of contents, and a card desiring an analysis, it is 

 impossible to answer this question. 



This particular case is not uncommon. In other in- 

 stances, both lead and morphine have similarly been found, 

 their presence being the result of legitimate medicinal 

 dosage. 



2. In the majority of cases the best material for research 

 is contents of the stomach or intestines, not from the 

 scientific, but from the practical point of view. In poison- 

 ing there is almost invariably a large overdose, and the 

 unabsorbed excess can be separated and detected with 

 facility from contents. In spite of the consensus of text- 

 book opinion, our repeated experience, both in practice and 

 experimental work, is that alkaloids cannot be satisfactorily 

 separated from liver, kidney, or even urine. The case is 

 different with metals and such poisons as cyanides, where 



