the symptoms bears to the last article of food or drink that was taken.
I believe that the effects of the common narcotics, in the cases where
they prove fatal, begin not later than an hour, or at the utmost two
hours, after they are taken; and in a great majority of instances they
begin in a much shorter time, namely, in fifteen or thirty minutes.
Hence if it can be proved that the nervous symptoms, under which a
person died, did not begin till several hours after he took food, drink
or medicine, it appears almost, if not absolutely certain, that a
narcotic poison cannot have been the cause of death. To some narcotic,
or rather narcotico-acrid poisons this rule certainly will not apply,
such as the poisonous fungi and spurred rye; which seldom begin to act
for several hours, sometimes for not less than a day and a half. Neither
will the rule apply to poisoning with the deleterious gases, as their
action has no connexion at all with eating or drinking. But these facts
do not form a material objection to the rule laid down; because the
circumstances under which cases of the kind occur are generally so
apparent, as at once to point out their real nature to a careful
inquirer.
In regard to apoplexy as the disease which resembles most closely the
effects of the narcotics, it was formerly stated that this disease is
apt to occur soon or immediately after taking a meal (p. 95).[1630] In
the greater number of such cases, however, where the meal has been the
exciting cause of the disease, the symptoms have begun _immediately_
after, or even during a meal. This is very rarely the case with the
symptoms of narcotic poisoning, and never happens in respect to those of
the commonest of the narcotics, opium: An interval of 10, 15, 20 or 30
minutes always occurs. The deleterious gases and hydrocyanic acid, with
its compounds, are the only familiar narcotic poisons which act more
swiftly.