Treatise on Poisons by Sir Robert Christison
3. In the last edition of this work I proposed for the detection of
1314 words | Chapter 76
hydrochloric acid in _compound organic mixtures_ a process, to which
Professor Orfila has since made an important addition,[312] and which
the investigations of that toxicologist, as well as my own, lead me to
suppose superior to any other yet suggested, although it is not entirely
free from objection. This process divides itself into two, according as
the subject of analysis is acid or neutral; but in the latter case its
indications are of dubious import.
a. If the matter to be examined be acid, boil it with water if
necessary, filter, and distil it with a gentle heat till the residue
acquire the consistence of a very thin syrup. Subject the distilled
liquor to the tests for diluted hydrochloric acid. It will seldom be
found there, however, because it is apt to be retained by the
co-existence of organic matter. If it be not found, add to the thin
extract in the retort a slight excess of a strong solution of tannin,
filter, and distil the filtered liquid by means of a hot bath of
solution of hydrochlorate of lime (consisting of two parts of
crystallized salt and one of water,)—taking care that the temperature of
the bath never exceeds 240°; and stop the distillation just before the
residuum becomes dry. Examine now the distilled liquor with the tests
for diluted hydrochloric acid.
Hydrochloric acid has a tendency to adhere with obstinacy to organic
matters, especially when these are abundant; and therefore Orfila
properly proposes to remove organic principles as far as possible by
precipitating them with solution of tannin. I have found, as he did,
that the acid may be obtained by distillation after this measure, when
it could not be obtained previously.—Orfila objects to the process
however that hydrochlorate of ammonia will pass over in the
distillation. But I have not found this to be the fact, when the
temperature did not rise above 240°; which in his experiments seem to
have been considerably exceeded.—A more important fallacy is, that
hydrochloric acid will be indicated by the process in a mixture which
contains both a neutral chloride, such as common salt, and sulphuric
acid. This fallacy can only be obviated by ascertaining that sulphuric
acid is not present.—But the most important fallacy of all is, that free
hydrochloric acid constitutes an essential part of the gastric juice,
and an ingredient of the secretions of the stomach in various states of
disordered digestion.[313] It is not easy to see how this fallacy can be
obviated, unless the acid be obtained in large quantity; nor am I
prepared to say what quantity would justify the conclusion, that the
acid had been derived from an external source. Dr. Prout once found
between four and five grains of pure acid in sixteen ounces of the fluid
of water-brash.[314] The quantity of hydrochloric acid is to be known by
drying, heating and weighing the chloride of silver thrown down in the
distilled fluid by nitrate of silver, and allowing 100 parts of
concentrated commercial acid for 145 of chloride.
b. When the mixture is neutral, hydrochloric acid can be no longer
detected in it without the aid of sulphuric acid to decompose the
chloride that has been formed. This should be added to the filtered
fluid obtained after organic matter has been separated by solution of
tannin. Hydrochloric acid will then distil over.—It is seldom however
that the discovery of the acid in this way will warrant the conclusion,
that it had ever existed free in the mixture whence it is obtained. For
it may have proceeded from chlorides contained in the subject of
analysis from the first, more especially chloride of sodium, which
exists in small quantity in all animal fluids and solids, and more
largely in many articles of food and drink. The only circumstance indeed
in which the detection of hydrochloric acid by decomposition with
sulphuric acid will yield any evidence,—and even then the evidence will
only be presumptive,—is when it is known that an earth or alkali was
given as an antidote, and when the alkali or earth which was used is
found in the suspected substance.
SECTION II.—_Of the Action and Symptoms produced by Hydrochloric Acid._
Hydrochloric acid has been found by Professor Orfila to exert the same
action as sulphuric and nitric acids; but it is a less powerful
corrosive and irritant.—In the gaseous state, it is a most destructive
poison to vegetables, as will be shown in the article on the Poisonous
Gases.
The symptoms it occasions in man are very like those produced by
sulphuric acid. As few cases however of poisoning with this substance
have yet been published, its effects are not so well known as those of
the other powerful acids; and it may therefore be right to mention the
leading particulars of some of the cases which are met with in
authors.—Mr. Quekett has related the case of a man, who, on arriving at
home one day, told the woman he lodged with that he had poisoned himself
with spirit of salt, but presented at the moment so little sign of
uneasiness, that she at first scarcely believed him. In a short time
however he suddenly became faint and fell down. On being removed to the
London Hospital, magnesia and milk were given, about three hours after
the acid had been taken; but no relief was experienced. He suffered
intense thirst, complained of excessive pain in the stomach and throat,
and expired in about fifteen hours.[315]—Mr. J. F. Crawfurd of Newcastle
has related a still more rapid case which was occasioned by two ounces
of an equal mixture of hydrochloric acid and “tincture of steel,”
probably the tincture of chloride of iron. Vomiting occurred soon
afterwards, but subsequently ceased; there was no complaint made either
of pain or heat anywhere, or of thirst; and questions were answered
intelligently. But the pulse was imperceptible, and the muscles of the
extremities contracted; and death took place in five hours and a
half.[316]—Orfila mentions that an hospital patient, affected with
inflammation of the brain after a fall on the head, having got by
mistake from his nurse 45 grammes, or two fluid ounces, of hydrochloric
acid, was attacked with acute pain in the stomach, efforts to vomit,
hiccup, extreme restlessness, a small pulse, a fiery red tongue,
blackness of the lips, and a burning skin; and next day he died in a
state of constant delirium, and covered with a cold clammy sweat.[317]
These cases present nearly the same violence and variety of action with
that which results from the two other acids.
SECTION III.—_Of the Morbid Appearances caused by Hydrochloric Acid._
The morbid appearances are on the whole similar to what are caused by
sulphuric acid. In Mr. Quekett’s case the stomach outwardly was
leaden-coloured and its vessels gorged with black blood; the intestinal
peritonæum injected and speckled with fibrinous effusion; the villous
coat of the stomach lined with yellow, curdled milk, and itself
irregularly black here and there, as if charred, and in some places
softened and corroded, so that a rent was made in handling it; the inner
membrane of the duodenum similarly affected, and also even the jejunum,
though more irregularly. The contents of the stomach were not acid, and
did not contain any chloride.—In Mr. Crawfurd’s case the villous coat
presented black elevated ridges, as if charred, and the furrows between
were scarlet-red; black granular extravasation had taken place at many
points into the submucous tissue; similar appearances were seen in the
duodenum and jejunum; and the lower part of the gullet looked as if it
had been cauterized.—In the case related by Orfila the gullet and
pharynx were red, and at one or two places excoriated; the stomach
inflamed externally, and its inner membrane spotted with gangrenous (?)
patches, and very brittle; the duodenum thickened, and the jejunum
perforated by a round worm.
Reading Tips
Use arrow keys to navigate
Press 'N' for next chapter
Press 'P' for previous chapter