Metallic arsenic is inert, and is not used in medicine,
Obtained principally as a secondary product in the roasting of cobalt ores. It is not a true acid, but an anhydride, or acid deprived of its water. All the preparations of arsenic are derived from white arsenic.
Arsenic in concentrated form applied to the tissues causes inflammation, followed by ulceration and sloughing. It has therefore been used as an escha-rotic, but its action is very painful and is attended with danger, as arsenic is readily absorbed from broken skin, ulcers, and mucous membrane, unless there is enough inflammation to throw it off; it being understood that when an inflammatory process is going on, the absorptive capacity of that part is checked.
In the stomach in medicinal doses arsenic does not combine with the albuminons contents of the organ, but remains unchanged and acts directly on the mucous membrane, stimulating the nerves and vessels, causing a sense of heat and hunger, and promoting the gastric functions.
Arsenic enters all organs and tissues, increases tissue changes and the vital activity of the whole system. It does not combine with the tissues, and is excreted chiefly by the urine, and also by the skin, liver, and intestines. Arsenic is therefore, in medicinal doses, a stomachic and general tonic, increasing the appetite and improving digestion and general nutrition.
It stimulates the secretions, peristaltic action, the brain, heart, and respiratory centre.
In giving arsenic, the first signs which indicate overdosing are: a slight puffiness about the eyelids, without redness, and noticeable first in the early morning, disappearing later; an itching of the eyelids; tingling or itching of the fingers, abdominal pain or soreness. Increasing symptoms of over-dosing are: a metallic taste, nausea, vomiting, diarrhoea, and sometimes dysenteric stools, with tenesmus; an irritable and feeble heart action; palpitations and oppressed breathing; eczema and other skin eruptions; trembling and stiffness of the joints; and albuminuria.
In acute arsenical poisoning two effects are produced upon the tissues:
1. The epithelium of mucous membranes is desquamated, especially in the alimentary canal.
2. The blood-vessels in the splanchnic area are widely dilated.
These two conditions give rise to clear watery stools - "rice water stools," - which are characteristic of arsenical poisoning and Asiatic cholera.
In acute poisoning the symptoms are of two varieties, gastro-intestinal and cerebral. The former is much more common, and is marked by a burning pain at the epigastrium, radiating over the abdomen; violent and uncontrollable vomiting of matter, first mucous, then bilious, and finally serous; intense thirst and dryness of the mouth and throat; stools bloody and offensive, sometimes involuntary; strangury; sometimes bloody urine, or suppression; great restlessness and agitation; dyspnoea; a rapid, weak, intermittent pulse; cold breath; shrunken face; cold and clammy skin, and final collapse, consciousness being retained until death occurs. In the cerebral form there is sudden and deep insensibility, ending in death, without intestinal symptoms. Occasionally there is a combination of both sets of symptoms; also they may vary according to the form and dose in which the poison has been taken. The time in which they come on is usually from half an hour to an hour after taking the poison, and death has occurred in a few hours, but the average length of time is about twenty-five hours. It often happens that recovery is made from the first effects, with death from exhaustion or secondary causes many days, or even weeks, after.
The signs to be watched for in the administration of arsenic are:
1. Puffiness about the eyes in the early morning.
2. Constriction of the throat.
3. Gastric disturbances - indigestion, pain, nausea, etc.
4. Pigmentation of the skin.
5. "Rice water stools."
The arsenic should be discontinued for a short time, but may be resumed unless the symptoms were alarming.
The fatal dose for an adult may be put at from 2 to 4 grains.
In treating poisoning by arsenic, if vomiting has not already been caused by the poison, emetics should be given: a tablespoonful of mustard in a glass of warm water, followed by large quantities of mucilaginous and albuminous drinks, such as flaxseed tea, milk, with white of egg, etc. The antidotes, hydrated sesquiox-ide of iron and hydrated magnesia, have been described under iron and may be given in water, a tablespoonful at a time, every few minutes while necessary. Castor-oil should be given to clear the bowels. If the poison has been taken in solution, the antidotes will precipitate it in an insoluble form, but no confidence can be placed in them if the powder has been taken, as rat-poison (often used in suicidal cases). The early and complete removal of the poison by emetics and purgatives is then the only real hope. The urine must be watched, as suppression may occur, and, while the patient lives, a daily specimen saved for examination.
Arsenic is not accumulative, and is an irritant, not a corrosive, poison. After death the stomach and intestines are found to be deeply reddened and inflamed, but not ulcerated. The post-mortem appearances, as well as many of the symptoms, resemble those of cholera very strongly. Chronic poisoning is caused by the inhalation of arsenical fumes, by the use of wall-papers and clothing dyed with materials containing arsenic, and by eating adulterated candy and other articles of food.