In the pure state, there can exist no difficulty in identifying it; its specific gravity, and its action on vegetable matter, will, without any other tests, be quite sufficient to fulfil our object. If heated with metallic mercury, it will disengage sulphurous acid gas; and if united with lime, a sulphate of lime will be produced, which the chemist may easily recognise by dissolving a portion in distilled water, and assaying the solution by muriate of baryta, which will produce with the sulphate a precipitate, insoluble in nitric acid. By the last mentioned tests we shall be enabled to detect the presence of sulphuric acid, in whatever state of complication it may happen to exist with alimentary matter.
Nitric Acid.
This acid, when pure, assumes the form of a limpid fluid, emitting white fumes of a suffocating odour; its taste is highly acid, and corrosive; and it is at once distinguished from all other acids, by its tinging the skin indelibly yellow. When of the specific gravity 1·5 it contains 74·895 per cent of dry acid, (whose ultimate elements are one proportional of nitrogen, and five of oxygen) the complement 25·105 parts, is water.[[322]] It is decomposed with violent action by all combustibles, and when mixed with volatile oils it causes their inflammation.
From the facility with which this acid undergoes decomposition, it is rarely found in commerce in a colourless condition; indeed the action of light is sufficient to impart a tawny tinge to it; when this change has proceeded to such an extent as to render the acid orange coloured, it is called Nitrous acid, or, in the language of the arts, aqua fortis, although in a chemical point of view, such a nomenclature is incorrect, for it is nothing more than nitric acid, holding nitrous acid gas loosely combined.
Symptoms of Poisoning by Nitric Acid.
This acid has been so frequently swallowed in France, for the purpose of committing suicide, that it has enabled the pathologists of that country to afford a very satisfactory account of its operation, and effects. To M. Tartra we are particularly indebted for a very full and interesting investigation of the subject, and we shall avail ourselves upon the present occasion, of the many facts and observations with which his treatise[[323]] abounds. In describing the symptoms occasioned by the ingestion of this acid, M. Tartra establishes four different gradations, viz. 1. When the death is speedy, for it is never sudden, it commonly takes place from the primary effects in about twenty-four hours, varying from six to forty-eight hours. 2. When it proves fatal from its secondary effects, at different intervals, from fifteen days to several years. 3. When death does not take place, but the recovery is imperfect. 4. When a perfect cure is sooner or later obtained. The first case is illustrated by the following example, which will serve to convey a very just idea of the progress and intensity of the symptoms. “A man, driven by distress to commit suicide, under the greatest agitation of mind, and upon an empty stomach, swallowed, at a draught, two ounces of concentrated nitric acid. Instantly he was seized with the most excruciating pains and agitation, and could not lie in bed, but rolled himself upon the floor. Vomiting came on, accompanied by a general sensation of coldness, especially in the extremities. Every time he vomited, the matter effervesced upon the pavement. A solution of soap and oil was administered to him, and in two hours he was brought to the hospital, often having vomited, and stopped on the road to drink. On his arrival, he had emollient drinks, especially linseed tea, in great abundance. He was in continual agitation, and his countenance was greatly altered. He now vomited every instant a blackish glairy matter; he opened his mouth easily, and his tongue was white, with a tinge of yellow; he complained of acute pains in his mouth, along the œsophagus, and in his stomach. His belly, slightly tense, could not bear the slightest pressure, without great torment. The surface of the body was cold; the pulse small and frequent; he had hiccup, and the respiration was laborious.
His symptoms increased. He uttered sighs and lamentations; his limbs became icy; a cold sweat covered his whole body; his pulse was scarcely perceptible; the pain was constant; still he could rise and make continual but useless efforts to quench his thirst, and satisfy his urgent desire to void urine, and go to stool. He continued in this state during the night; the matters vomited became more clear, and of a yellow colour. He at last made a few drops of urine. The shocking appearance of his body already resembled that of a corpse, but he retained his senses, and was speaking when he expired, nineteen hours after swallowing the acid.” The burning heat and pains which are commonly the immediate effects of the ingestion of this acid are very variable in their intensity and duration, and M. Tartra observes that, in general, they are not in proportion to the quantity or strength of the acid swallowed. It often happens that persons who have taken only a small dose, are seized with the most excruciating and dreadful pains, and some of those who have swallowed a great quantity, two or three ounces for example, have had scarcely any suffering, but remained very tranquil. In the first case, the patients either recover, or survive a long time; in the second, speedy death is almost always the consequence; thus a young man of twenty died in twenty hours, without any agitation or signs of acute pains. On opening the body, the highest degree of disorganization appeared, perforations of the stomach, and great effusion of its contents into the abdomen. The second variety of the progress and termination of poisoning by nitric acid, exhibits, at first, the same phenomena as the preceding; but less alarming symptoms succeed by degrees; after some months, the inner membrane of the alimentary canal detaches itself in portions, the patient falls into a marasmus, and dies. We are here presented with a case of consecutive poisoning, see page [147].
The third termination is in imperfect recovery. A slow and progressive amendment ensures the safety of the patient; but there still remains some complaint; obscure pains in the throat, and especially in the epigastric region; habitual constipation, occasional vomiting, and increased sensibility of the stomach, so that it can only support light nourishment and bland liquors; in short, they continue invalids during the rest of their lives; they are subject to repeated and even habitual indispositions, and sometimes to pain and insupportable heat of the stomach; but they are able to follow their occupations, and long survive their poisoning.
The total disappearance of the symptoms produced by swallowing nitric acid; or complete and absolute recovery without leaving any consequences, is the last variety of termination.