o cause death. A poison may not be
detected in the body, owing to defective methods, smallness of the dose
required to cause death, or to its ejection by vomiting or its
elimination by the excretions.

5. _Conduct of Suspected Persons._--A prisoner may be proved to have
purchased poison, to have made a study of the properties and effects of
poison, to have concocted medicines or prepared food for the deceased,
to have made himself the sole attendant of the deceased, to have placed
obstacles in the way of obtaining proper medical assistance, or to have
removed substances which might have been examined.

V.--SYMPTOMS AND POST-MORTEM APPEARANCES OF DIFFERENT CLASSES OF POISONS

Whilst recognizing the fact that toxic agents cannot be accurately
classified, the following grouping may for descriptive purposes be
admitted with the view of saving needless repetition:

1. =Corrosives.=--Characterized by their destructive action on tissues
with which they come in contact. The principal inorganic corrosives are
the mineral acids, the caustic alkalies, and their carbonates; the
organic are carbolic acid, strong solutions of oxalic acid, and acetic
acid.

_Symptoms._--Burning pain in mouth, throat, and gullet, strong acid,
metallic or alkaline taste; retching and vomiting, the discharged
matters containing shreds of mucus, blood, and the lining membrane of
the passages. Inside of mouth corroded. There are also dysphagia,
thirst, dyspnoea, small and frequent pulse, anxious expression, shock.
Death may result from shock, destruction of the parts--_e.g._,
perforation of stomach or duodenum, suffocation; or some weeks
subsequently death may be due to cicatricial contraction of the gullet,
stomach, or pylorus.

_Post-Mortem Appearances._--Those of corrosion, with corrugation from
strong contraction of muscular fibres, and followed by inflammation and
its consequences. The mouth, gullet, and stomach, and in some cases the
intestines, may be white, yellow, or brown, shrivelled and corroded. The
corrosions may be small, or may extend over a very large surface.
Sometimes considerable portions of the lining membrane of the gullet or
stomach may be discharged by vomiting or by stool. Beyond the corroded
parts the textures are acutely inflamed. The stomach is filled with a
yellow, brown, or black gelatinous liquid or black blood, and may in
rare cases be perforated.

2. =Irritants.=--These are substances which inflame parts to w