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196 DENTAL MEDICINE.
continually increasing doses are administered, the arsenic accumu-
lates, and poisonous symptoms quickly appear ; hence, it is rec-
ommended to begin a course of arsenic with large doses, and the
quantity given regularly reduced. When arsenious acid is ad-
ministered, the bowels should be well evacuated by a purgative,
given previously, and the arsenic taken directly after a meal, but
never upon an empty stomach, on account of gastric irritation.
Its use should be omitted for a day or two every two or three
weeks, and a mild aperient employed, in order to prevent the ac-
cumulation of the arsenic in the system. A few drops of laud-
anum added to the arsenical preparation will prevent nausea and
vomiting. All arsenical preparations should be administered with
the greatest regularity, at stated times.
During the employment of arsenic, the eyes of the patient
should be examined daily, and if the eyelids and conjunctiva be-
also, when
come inflamed, the remedy should be discontinued ;
the urine, from being pale and copious, becomes scanty, acid and
high-colored, the arsenic should be suspended.
Poisonous symptoms have been caused by half a grain of arsen-
ious acid, and fatal effects have followed the administration of two
grains, although much larger quantities have been taken with im-
punity ; very large quantities often cause emesis, which removes
the substance frdm the stomach, and thus prevents fatal effects.
When the idiosyncrasies of the patient are unknown, it is better
to use small doses before beginning with large doses. The
quantity of arsenic required to produce a fatal effect varies ac-
cording to the susceptibilities of the patient and the state of the
stomach. Much, however, depends on the idiosyncrasies of the
individual, which differ greatly in different persons. When large
quantities are taken, the effects are sometimes manifested on the
cerebro-spinal system, death following, from narcotism, in a
short time.
The amount of arsenious acid which may be safely introduced
into the stomach should never be equaled in an application to the
pulp of a tooth. One-twentieth of a grain may be a safe dose
medicinally, but a much less quantity is sufficient for devitalizing
the pulps of teeth.