Tartra has furnished us with the following interesting account of the dissection of those who have died of the primary effects of nitric acid. The external appearance of the body presents no alteration; every part is sound and natural, and possesses, in a certain degree, the firmness and freshness of life. The epidermis of the margins of the lips has commonly an orange colour, more or less deep. It seems burnt and easily separates. Sometimes yellow spots are discovered on the hands and other parts of the body, caused by the contact of the acid. A yellow fluid, in some cases very abundant, flows from the mouth and nostrils, and the belly is considerably distended with air. The alimentary canal is remarkably affected. All the internal membrane of the mouth is burnt, and has sometimes a white colour, but is more commonly yellow; it is separate in some places, and adheres in others. The teeth are often loose, and have a very marked yellow colour at their crown. The mucous membrane of the pharynx exhibits the same change, or is in a state of inflammation of a dirty red colour. The whole extent of the œsophagus is lined with a dense mass of a fine yellow colour, dry on its surface, unctuous and greasy to the touch, and which seems to be formed both of the mucous membrane, altered in a particular manner, and of the albumen contained in the viscid fluid which exudes from the membrane of the œsophagus, solidified by the nitric acid. This lining adheres in very few points, and is easily detected from the other membranes of the œsophagus, which are brown and blood-shot. When the stomach is not perforated, it has commonly a considerable size; externally, its membranes are slightly and partially inflamed, but very much towards the pylorus and beginning of the duodenum. Its colour is faded, livid, of a yellowish green, with large gangrenous spots. It adheres every where to the neighbouring parts, the diaphragm, liver, spleen, and transverse arch of the colon, by means of a concrete lymphatic exudation; its sides, which are thin and yellow in some places, and thick and black in others, exhibit net-work of dilated blood-vessels filled with black coagulated blood. Often there are several points of the stomach dissolved, and ready to burst with the slightest touch; it contains a great quantity of gas, which has a peculiar smell, resembling that of bitter almonds; it also very commonly contains a great quantity of yellow matter, of a pultaceous consistence; the substance of the stomach is generally swelled in some places, and deeply marked with black, without being dissolved; this effect is most remarkable at the great end, into which the acid seems to fall by its weight; the rugæ of the stomach are very brown, and are reduced to a mucilaginous consistence. The other parts of the alimentary canal exhibit the same organic lesions, although the phenomena have less intensity in proportion as the part is more distant from the stomach.
In those cases where the stomach is found perforated, its bulk is very small; the holes commonly occur in the large and small extremities; their form is circular, and their edges thin, and as if dissolved. The urinary bladder contains no urine, although the patient have not discharged any.
The appearances upon dissection of those who die of the secondary effects are entirely different from those above described. It would be difficult to find an example of greater emaciation, more advanced consumption, or more disgusting form. Nothing is equal to the degree of withering, and decrepitude of the whole organs; their colour is faded; the internal cavities do not contain the usual serum; the cellular and muscular systems are almost annihilated; the bones become dry, as in persons of advanced age, and break with extraordinary facility; but these changes are general and secondary, and depend upon local organic derangement of the alimentary tube. The stomach and whole intestinal canal are contracted to an extremely small size; the intestines are not larger than the little finger, sometimes not exceeding a thick writing quill; their coats are very thick, their cavity almost obliterated, and containing only a little mucosity. The stomach, which often resembles a portion of a small intestine, appears sound externally, and only presents some adhesions to the neighbouring viscera; internally, the most remarkable change is the contraction of the pylorus, the passage through which will scarcely admit a probe; and the membranes of the stomach itself are so thickened and compacted around it, that they have lost all their natural suppleness. On the internal surface, there are irregular spots, or rather smooth and red places, which seem to be covered with a regenerated mucous membrane, less villous than that which had been destroyed by the action of the acid; these cicatrices are particularly large and numerous in the great end of the stomach, and around the circumference of the pylorus.
Chemical processes by which the presence of Nitric Acid may be discovered.
If the acid be in any quantity, and without mixture, there cannot exist any difficulty in demonstrating its presence. If added to copper filings, there will be a copious disengagement of orange-coloured fumes, and a nitrate of copper of a blue colour will remain, as the product. If it be saturated with potass, we shall at once obtain by due evaporation the well known substance, nitre; this salt will announce its nature by deflagrating with charcoal or sulphur. This latter test is the one we must employ for the detection of nitric acid, when mixed with vinegar, and other liquids. Where the acid has combined with the animal matters with which it may have come into contact, they must be boiled for an hour in a solution of pure potass, when the solution will assume a reddish appearance; this must be filtered, and evaporated in a capsule of porcelain, when the mass so obtained will leave a residuum of nitrate of potass.
Dr. Marcet, in a paper just published in the Philosophical Transactions,[[324]] on the composition of sea water, employed a new mode of assaying the solution for nitric acid, and for which he acknowledges himself indebted to Dr. Wollaston. Having concentrated the bittern in a glass vessel, until it began to deposit solid matter, he added sulphuric acid and gold leaf, and boiled the mixture; the gold leaf was not in the least acted upon, nor was any smell of nitric acid perceived; but on adding the smallest quantity of nitre to the same mixture, the gold was dissolved, and the smell of aqua regia instantly perceived. The rationale of the experiment is obvious, gold, although insoluble in muriatic acid, is instantly dissolved on the addition of nitric acid, in consequence of the developement of chlorine.
Spirit of Salt. Muriatic Acid.
The liquid acid, of which we are about to treat, is a solution of muriatic acid gas in water; when of the specific gravity 1·16, according to Davy, it contains 32·32 per cent. of the gas, which recent experiments have proved to be a compound of Chlorine (oxy-muriatic acid) and hydrogen, in equal volumes. It has accordingly received a name expressive of its composition, and is called Hydro-chloric acid. Its odour is strong and peculiar; when exposed to the air it emits white fumes; its taste is intensely sour and caustic; it is, however, the weakest of the three mineral acids, and no remarkable elevation of temperature is produced by dilution. It readily combines with potass, soda, &c. and furnishes a class of salts which may be easily recognised by their characters.
Symptoms of Poisoning by Muriatic Acid.
As the effects of muriatic acid do not differ from those which have been described, as the consequences of poisoning by the other mineral acids, it will be unnecessary to enumerate them. Orfila, however, remarks, that the patients who have swallowed a certain quantity of it, emit, in the first moments of the accident, a thick smoke of a white colour, and very pungent smell.