Part 3 (1/2)
_Symptoms._-The effects of poisoning by oxalic acid are peculiar. When the dose is large (half an ounce or more) and the solution concentrated, it proves very rapidly fatal. It produces a hot burning sensation in the fauces and sophagus in the act of swallowing, severe burning pain in the stomach, and in most instances immediate vomiting. The vomited matters are strongly acid, of a dirty green or black color, and consist of the contents of the stomach with altered mucus and blood. The remaining symptoms are a sense of constriction or suffocation, lividity of the countenance, great prostration of strength, feeble pulse, cold clammy perspirations, and convulsions, which speedily terminate in death. When a smaller quant.i.ty has been taken, much diluted, its corrosive properties are weakened or destroyed, but the nervous symptoms, as cramps and numbness, may be well marked.
In cases of recovery the mouth may remain sore for some time, the tongue swollen, the abdomen tender, the stomach very irritable, and there may be troublesome diarrha. In two instances there has been loss of voice for several days, owing to the action of the poison on the nervous system. Twitching of the muscles of the face and extremities has also been observed.
_Post-mortem Appearances._-The mucous membrane of the fauces, sophagus, and stomach is generally white and brittle, but often colored with the brown mucous matter discharged. The stomach often contains a black fluid, like coffee-grounds, consisting princ.i.p.ally of altered blood; and its sub-mucous coats are vascular and dark colored.
The stomach though seldom perforated, may yet be so softened as to be with difficulty removed entire, and sometimes this is not possible. This softening may be due to the post-mortem action of the poison; but its effects during life in softening and bleaching the mucous membrane are sufficiently marked. Occasionally the stomach is black and gangrenous looking. If death has occurred quickly, the small intestines are seldom much affected; but where the symptoms have been protracted there are usually signs of congestion and inflammation.
_Treatment._-Chalk, whiting, or magnesia, suspended in water, or in some demulcent fluid, must be administered immediately; and if necessary, vomiting should be excited by tickling the fauces, or administering emetics of sulphate of zinc and ipecacuan, followed by large quant.i.ties of emollient drinks. The antidote, to be effective, must be given as soon as possible, the plaster of the apartment, or any form of mortar being used in the absence of the remedies just mentioned.
Alkalies (soda, potash, or their carbonates) are not only useless, but they form salts with oxalic acid, which are as injurious as the acid itself. When there are symptoms of collapse, stimulants are to be freely employed.
From the tendency to softening, the stomach-pump should not be used.
_Tests._-Crystals of oxalic acid are met with as four-sided prisms, colorless, without odor permanent in the air, and very acid; this last character distinguis.h.i.+ng them from crystals of sulphate of magnesia and sulphate of zinc. The crystals, when heated, melt, and are dissipated without combustion, and leaving no residue. This character is important as a means of distinguis.h.i.+ng oxalic acid from other similar crystals.
They are soluble in from eight to twelve parts of cold water. This acid may be thus recognised in solution:
1. _Nitrate of silver_ throws down, with oxalic acid, an abundant white precipitate (oxalate of silver), which is soluble in nitric acid. The oxalate of silver, when dried and heated on platinum foil, detonates, and is dissipated in a white vapor.
2. _Sulphate of calcium_ causes a white precipitate with oxalic acid (oxalate of calcium) which is soluble in nitric or hydrochloric, but not in any vegetable acid.
The solution containing the acid should be concentrated before testing, if it be not present in considerable quant.i.ty.
Lime water and all soluble lime salts throw down precipitates with oxalic acid; but as these are liable to be mistaken for a precipitate with sulphuric acid, it is better to use sulphate of calcium which is slightly soluble, as the test agent. A good deal of the test solution must be used, and the precipitate takes time to settle.
3. _Sulphate of copper_ gives a faint bluish precipitate with oxalic acid (oxalate of copper), which is not redissolved by a few drops of hydrochloric acid.
These tests will not act if the solution contain nitric acid in excess, in which case the liquid must be evaporated to crystallization, and the crystals washed and redissolved in water.
These tests for oxalic acid should never be applied without previously separating it from all organic matter. This is best done by first of all acidulating the suspected fluid with acetic acid, and then adding acetate of lead, which combines with the oxalic acid to form a white insoluble salt, which may ordinarily be removed by filtration or subsidence. This filtrate, after being well washed, is to be diffused in water, and into this a current of sulphuretted hydrogen gas is to be pa.s.sed for some considerable time. This will throw down the lead as sulphide, leaving the oxalic acid in the fluid; any organic matter will also be carried down. Filtration will separate the solids from the liquid containing the acid, which may now be evaporated until crystals are formed, which may be tested in the usual way.
ACETIC ACID.-Although this acid, in its concentrated state, is highly corrosive, yet it is very seldom brought under the notice of the toxicologist.
In the case of a young woman reported by Orfila, death quickly occurred after several attacks of convulsions. At the subsequent post-mortem examination, the integuments of the dependent parts of the body were found very livid; the tongue and sophagus were of a dirty brown color, the latter being intersected by a fine net-work of capillary vessels; and the interior of the stomach was interspersed with black elevations caused by the presence of coagulated blood in the sub-mucous areolar tissue. The mucous membrane was entire.
As regards the _treatment_, it is only necessary to administer draughts containing magnesia or its carbonate, followed by mucilaginous or demulcent drinks.
TARTARIC ACID, though not a corrosive, may be here placed along with the other vegetable acids. Strange as it may seem, tartaric acid has destroyed life in at least one instance in this country; an ounce having been given in mistake for an aperient salt. The deceased swallowed the whole at once, and immediately called out that he had been poisoned. He complained of intense pain in the throat and stomach, as if he had swallowed oil of vitriol, or was on fire. Soda and magnesia were administered without avail; and after death, at the end of nine days'
suffering, the stomach and intestines were found much inflamed.
CHAPTER VIII.
THE CAUSTIC ALKALIES AND THEIR CARBONATES; POTASH, SODA, AMMONIA.
The second division of the cla.s.s of Corrosives has now to be considered.
It contains the Caustic Alkalies, and some of their Salts. Poisoning by any of these agents is rare.