but sometimes
it is only deoxidized air with an excess of carbonic acid gas.

_Symptoms._--If poison concentrated, death may ensue at once; if gas
diluted, or exposure only short, insensibility, lividity, hurried
respiration, weak pulse, dilated pupils, elevation of temperature to
104 deg., tonic convulsions not unlike those of tetanus.

_Treatment._--Fresh air, oxygen, with artificial respiration.
Stimulants, hypodermic of strychnine, and alternate hot and cold douche.

=Irritant Gases= are--(1) Nitrous acid gas; (2) sulphurous acid gas; (3)
hydrochloric acid gas; (4) chlorine; (5) bromine; (6) ammonia. They have
the common property of causing irritation and inflammation of the eyes,
throat, and air-passages, and may cause spasm of the glottis,
bronchitis, and pneumonia.

=Sulphurous Acid Gas.=--One of the products of combustion of common
coal.

=Hydrochloric Acid Gas.=--Irrespirable when concentrated, and very
irritating when diluted. Very destructive to vegetable life.

=Chlorine.=--Used in bleaching, and as a disinfectant. Greenish-yellow
colour, suffocating odour. In poisoning, inhalation of sulphuretted
hydrogen gives relief.

XXVIII.--VEGETABLE IRRITANTS

The chief vegetable purgatives are aloes, colocynth, gamboge, jalap,
scammony, seeds of castor-oil plant, croton-oil, elaterium, the
hellebores, and colchicum. All these have, either alone or combined,
proved fatal. The active principle in aloes is aloin; of jalap, jalapin;
of white hellebore, veratria; and of colchicum, colchicin. Morrison's
pills contain aloes and colocynth; aloes is also the chief ingredient in
Holloway's pills.

_Symptoms._--Vomiting, purging, tenesmus, etc., followed by cold sweats,
collapse, or convulsions.

_Post-Mortem Appearances._--Inflammation of alimentary canal;
ulceration, softening, and submucous effusion of dark blood.

_Treatment._--Diluents, opium, stimulants, abdominal fomentations, etc.

Certain of these irritant poisons exert a marked influence on the
central nervous system, as the following:

=Laburnum= (_Cytisis Laburnum_).--All parts of the plant are poisonous;
the seeds, which are contained in pods, are often eaten by children.
Contains the alkaloid _cytisine_, which is also contained in arnica. It
has a bitter taste, and is powerfully toxic. Symptoms are purging,
vomiting, restlessness, followed by drowsiness, insensibility, and
convulsive twitchings. Death due to respiratory paralysis. Most of