ARSENIC.
The element (arsenicum)—The oxide (white
arsenic)—Arsenicum—Arsenicum trioxide. Forms of: (1)
Crystalline—(2) Amorphous—Solubility. Uses and occurrences: (1)
Steeping wheat—(2) Preservation of skins—(3) Antiseptics—(4)
Glass making—(5) Fur in boilers—(6) Candles—(7) Preservation of
wood—(8) Sheep washes—(9) Scheele’s green and emerald green as
pigments in sweets (case of Franklin and Randall), wall papers, toys,
&c.—(10) Medicinal—(11) For horses—(12) Tooth-stopping—(13)
Aniline dyes—(14) Fireworks—(15) Rat and fly poisons (case of
Maria Gage)—(16) For cleansing metals—(17) Arsenic eaters—(18)
Cosmetics—(19) For bronzing metals—(20) Beer brewed from
glucose—(21) American paper collars—(22) Speculum metal—(23)
Inhalation for asthma and bronchitis—(24) Mineral waters. Sulphides
of Arsenic: (1) Orpiment (case of M. A. Burdock)—(2) Realgar.
Arsenic acid—The arsenates—Arsenic trichloride—Arseniuretted
hydrogen—Methods of extraction—Tests—Modifications of old
processes suggested—Marsh’s test, distinction of results in arsenic
and antimony—Reinsch’s test—Doses—Antidotes—Physiological
effects—Remarks—Did L’Angelier commit suicide?
THE name “arsenic” is applied to two things: in chemistry it means the
element As; in popular usage it signifies the oxide As_{2}O_{3}. In
our report, the element will be called _arsenicum_, the oxide simply
“arsenic” or “white arsenic.”
ARSENICUM,
Symbol As, is an element of steely metallic lustre, tarnishing to dull
dark grey, met with in crystalline (rhombohedral) fragments, so brittle
that they can be easily reduced to a dark grey powder, insoluble
in water, but slowly absorbing oxygen and dissolving, insoluble in
pure hydrochloric and in vegetal acids, and in alcohol, soluble (by
oxidation) in strong sulphuric and in nitric acid, in chlorine, in
solution of bleaching powder. Tasteless, and inodorous until heated,
when it sublimes, without melting, at 110° C. (Guy), and gives a
strong _odour of garlic_. Sp. gr. 5·8. The characters of the metal are
utilized in Marsh’s and other tests, hereafter described. Heated in
air, it oxidizes to white fumes of As_{2}O_{3}. It is employed chiefly
to harden lead in making _shot_, in the proportion of 0·3 per cent. The
use of these in cleaning bottles, &c., may contribute a trace of As:
the presence of a larger amount of _lead_ would in this case indicate
the source. Common Britannia metal, used for teapots, spoons, &c.,
often contains As. It occurs also in many minerals.
When oxidized it is poisonous, but _pure arsenicum_ passes through
the body of animals unaltered (Wagner’s Chem. Technology, trans, by
Crookes, 1872, p. 86). The vapour is very poisonous.
Arsenicum has two oxides, the trioxide and the pentoxide.
ARSENICUM TRIOXIDE.
_Synonyms._—Arsenious oxide, arsenious acid, arsenious anhydride;
popularly, “arsenic,” “flour of arsenic,” or “white arsenic:” in mining
districts it is sometimes called “mercury:” Latin, acidum arseniosum.
_Chemical formula_ As_{2}O_{3}, or two atoms (150 parts by weight) of
arsenicum, to three atoms (48 parts by weight) of oxygen.
_Forms._—(1.) _Crystalline_. By sublimation and slow condensation on
moderately heated surfaces, also by deposition from solution, we obtain
regular _octahedra_, often so modified as to appear like equilateral
triangular or hexagonal plates, or even elongated into triangular
prisms, but never in the form of regular _tetrahedra_ such as tartar
emetic yields. For figures, see Guy and Ferrier’s Forens. Med., 1881,
pp. 440 and 670. The crystals are transparent and highly refracting.
Sp. gr. 3·69. Volatilizes without melting, except under increased
pressure.
(2.) _Amorphous_ or _vitreous_. Suddenly cooled, As_{2}O_{3} condenses
as clear transparent drops, finally cohering into a glassy mass, sp.
gr. 3·74. When kept, this becomes opaque, perhaps owing to a change
into the crystalline variety, constituting the “porcellanous” form
found in commerce. If the lumps be broken, layers of still transparent
As_{2}O_{3} will be seen.
The _solubility_ depends on the variety, temperature, length of time
it is digested, fineness of powder, &c. So that exact figures cannot
be given, as hardly two authorities agree. It is certain, however,
that the amorphous form is less soluble than the crystalline.[131]
The accepted statement is that given by Taylor (Med. Juris. 1, 250):
that digested with cold water, from 1/500 to 1/1000 dissolves, equal
from one half to one grain per fluid ounce; if boiled for an hour and
allowed to cool, an average of twelve grains per fluid ounce remains
in solution; if boiled for a shorter time, less is dissolved. See also
Woodman and Tidy’s Forens. Med., 1877, pp. 133, 134. Organic matter
is said to decrease its solubility; I have not found that it does so
to any notable extent. Dr. Blondlot (Med. Times and Gazette, Feb. 11,
1860) states that fats, such as bacon, diminish the solubility; this
must be by coating the particles and preventing contact with water.
Powdered white arsenic in all cases refuses for a long time to become
moistened by water, floating on the top, and collecting in little lumps
as if greasy: the appearance is so peculiar as to have led sometimes
to its detection. Commercial powdered white arsenic is generally the
opaque form pulverized, but it may be crystalline.
As_{2}O_{3} is very soluble in potash and soda and their carbonates,
forming _arsenites_. It is less soluble in ammonia. In hydrochloric
acid it dissolves easily, forming _chloride of arsenic_. It is less
soluble (1 in 2,000) in alcohol than in water. One part dissolves in
200,000 of chloroform. It is insoluble in pure ether. It is heavy to
feel, _tasteless_, very faintly acid to test paper, and so feeble
in affinity that its soluble salts are strongly alkaline, and are
decomposed by all acids with separation of As_{2}O_{3}. The powder and
its vapour are inodorous, but when heated with charcoal or organic
matter it is reduced to arsenicum, with its odour of garlic.
_Uses and Occurrence._—1. As a preservative against insects and fungi,
for steeping seed-wheat. Many accidents have resulted. Birds poisoned
by it and afterwards eaten by man have occasioned severe symptoms. From
1830 to 1840 in France 235 accusations of arsenic poisoning occurred,
of which 110 were against agricultural persons, proving that the use of
the drug in farming gives dangerous facilities for crime. Sulphate of
copper, or, better, a mixture of sulphate of soda and lime, are more
effectual as preservatives, and the latter mixture is not poisonous.
(Lancet, 1849, Jan. 20.)
2. For preserving skins and furs (arsenical soap). This use has also
caused serious results in the operators. Stuffed birds, &c., kept
in living rooms may prejudicially affect the inmates by giving off
arsenical dust.
3. As an antiseptic it is injected in solution through the vessels of
subjects for dissection. Of course in this case the body would show
signs of the anatomical examination it had undergone. In the trial
of Professor Webster for the murder of Dr. Parkman, at Boston, U.S.,
March, 1850, the _absence_ of arsenic and other preservative substances
in the corpse proved that it had not been a subject for dissection.
4. In glass making and the production of opaque white enamels. Here
most of the vapour passes up the chimney and is diffused.
5. Some of the patent preparations for preventing “fur” in boilers have
contained alkaline arsenites.
6. Formerly wicks of candles were steeped in arsenic solution to
prevent a long “snuff” forming. Moreover, it was incorporated with the
candle itself to improve its appearance. The result was a constant
diffusion of arsenic vapour in the room. Tapers were also coloured with
emerald green (copper aceto-arsenite), which likewise gave rise to
arsenical fumes. These objectionable practices have been fortunately
given up, owing to the strong representations of scientific men.
7. Wood is sometimes preserved by a solution of arsenic, and then
tarred. This use would be practically free from danger, except to the
operatives.
8. An alkaline arsenite is used for washing sheep to destroy vermin.
The workmen sometimes suffer. (Lancet, 1857, p. 281.) Streams have
been poisoned, the solution has been drunk in mistake (Ibid, 1856, p.
447), and lastly, the sheep themselves have been killed (Taylor’s Med.
Juris., i. 272). Carbolic acid would probably answer better.
9. Cupric arsenite (Scheele’s green) and aceto-arsenite (Schweinfurth
or emerald green) are used as pigments. In one case, where a baker’s
shelves had been painted with this colour, emerald green was found
adhering to the bottoms of the loaves (Med. Times and Gaz., 1854,
p. 326). Blancmange (_R._ v. _Franklin & Randall_, Northampton,
1848[132]), ornaments on cakes (Lancet, 1849, Feb. 17th), sweets,
dresses, and artificial flowers (Husemann, Jahresbericht, 1872, p.
480), lamp-shades, insides of pasteboard cigar-holders, toys,[133]
wrappings for chocolate, &c., wafers, water and oil colours, and wall
papers have all been coloured with emerald green. Whenever such things
have been swallowed, _the green colour is seen in the vomit_. Boxes of
paints should never be given to young children. Cakes of emerald green
and of other poisonous colours have often been sucked or eaten with
fatal result; they are the more tempting as they are generally made
up with honey or glycerine. Bright green wall papers have gone out of
fashion, still many of the dull colours have emerald green in their
composition. Such papers certainly give off arsenical dust, even if
they do not evolve arseniuretted hydrogen or other arsenical gas, and
the symptoms they produce have been well authenticated. In a new house
the papers should always be tested. Messrs. Woollams, of Marylebone
Lane, were, I believe, the first to disuse arsenical pigments in
paper-hangings.
These arsenites of copper give, with a little ammonia, a blue solution
(due to the copper), in which a crystal of silver nitrate becomes
covered with a yellow coating of silver arsenite. The As can also be
easily found by the other tests.
Dr. Raseden of Mersberg finds that arsenical papers cause rheumatic
pains, neuralgia, cough, lassitude, and emaciation (Lancet, 1849,
April 7th). They also cause skin eruptions. These effects disappear
when the patients are removed. In Germany the use of these pigments
is prohibited; it should be so in England. Unfortunately no other
permanent green colour is so bright in tint.
The copper arsenites are insoluble in water, but soluble in acids,
hence are dissolved by the gastric juice, and then absorbed.
10. In medicine, arsenic is used for skin diseases, ague, and as a
tonic; externally for cancer and lupus. _Liquor arsenicalis_ B.P.,
Fowler’s solution, or “ague drops,” is composed of arsenic 80 grains,
potass, carbonate 80 grains, water 1 pint, flavoured with lavender. It
is a solution of potassium arsenite. _Liquor arsenici hydrochloricus_
is arsenic dissolved in hydrochloric acid, giving arsenic trichloride,
of the same strength as liquor arsenicalis. Among unofficial
preparations are “_Donovan’s Solution of Arsenic_,” containing
mercuric and arsenious iodides; strength 0·69 grain _arsenicum_ per
fluid ounce: “_Davidson’s Cancer Remedy_” equal parts of arsenic and
hemlock (Dr. Paris): “_Cancer Paste_,” containing 8 per cent. of
arsenic, with cinnabar and dragon’s blood: “_Hydrophobia Pill_,” 1/16
to 1/12 grain arsenic, with 1 grain pepper, an absurd remedy much
used in the East Indies. (Blyth’s Pract. Chem., 1879, p. 376.) The
pharmacopœial preparations of arsenic acid will be described under
_arsenic pentoxide_.
11. It is given by grooms to horses, to render their coats sleek, and
improve their wind, under the name of “condition balls or powders”
(strength 2½ to 5 per cent. of arsenic), also for worms, and as a tonic.
12. For destroying the nerves of decayed teeth, about 1/25 grain
is placed in the cavity. In the Lancet a case is recorded in which
inflammation and caries of the jaw followed this practice, which is a
very dangerous one.
13. In the manufacture of some aniline dyes, and in the reduction of
indigo, arsenic is often used. Dyed stockings, &c., have caused skin
irritation, supposed to be due to arsenic, but more probably owing to
the dye itself.
14. Firework preparations commonly contain some compound of As, and
therefore give poisonous vapours. “Bengal light” consists of 24 of
potass. nitrate, 7 of sulphur, and 2 of realgar (arsenic disulphide).
See also Blyth, Prac. Chem., p. 379.
15. _Rat Poisons_:—No. 1. Arsenic 6 per cent., made into a paste,
with equal parts of flour and suet, variously coloured and scented.
No. 2. Equal parts of arsenic and carbonate of barium (itself
poisonous), coloured with rose pink, and scented with oils of anise and
rhodium.[134]
_Fly Poisons._—“Fly powder,” a grey mixture of As and As_{2} O_{3}.
“Fly water,” a solution of arsenious acid, or arsenite of soda or
potash, of varying strength, sweetened with sugar, treacle, or honey.
(Med. Times and Gazette, Sept. 13th, 1851.) Some also contain orpiment
(arsenic trisulphide).
16. For cleansing metals, arsenite of soda has been used on account
of its strong alkalinity. It is an absurd preparation to use for this
purpose, as washing soda or potash would act better. In December,
1857, 340 children were poisoned by water from a boiler that had been
“cleaned” by this compound (Taylor on Poisons, 2nd ed., p. 378). In
1863, a man died from drinking beer out of a pot which had been thus
cleansed (Taylor, Med. Juris., 1, 273).
17. The well-known “arsenic eating” of Styria has been ridiculed as
impossible, but has yet been authenticated on further examination. A
Styrian wood-cutter was seen by a medical man to eat a piece of arsenic
weighing 4½ grains, and next day another 5½ grains, yet remaining in
his usual health. It is also eaten by the natives of Ceylon (Med. Times
and Gaz. 1862, p. 454, and 1866, p. 375). Workmen in arsenic factories
often become habituated to its influence. See a paper by Roscoe, Mem.
of Lit. and Phil. Soc. of Manchester, 1860. I myself can testify to
this fact. A student in the College of Science, Dublin, was accustomed
to take out of the arsenic bottle little lumps about 3 or 4 grains each
and eat them, without apparent ill effect.
18. As a cosmetic, applied externally, it would probably be useless.
Unless the skin were abraded, or it remained very long in contact,
no absorption, and hence no poisonous effect, would result, but any
scratch or wound would be dangerous. (See Christison’s Evidence, case
of Madeline Smith, p. 320.) And if in protracted contact with the skin,
it will cause symptoms. (Memoirs of Lond. Med. Soc., ii., 397, Amer. J.
of Med. Science, July, 1851.)
19. A solution of chloride of arsenic has been employed for “bronzing”
metals. The fumes would be highly pernicious.
20. Ritter, of Rouen, states that glucose or starch-sugar frequently
contains arsenic, derived from the sulphuric acid employed in its
manufacture being made from arsenical pyrites. He finds that by this
means the arsenic is introduced into _beer_ brewed with glucose, into
confectionery, syrups, liqueurs, &c. (Reimann’s Färber Zeitung, No. 3,
1878.)
21. It is said that certain paper collars and cuffs which are
extensively made in America have proved poisonous from containing a
considerable proportion of arsenic. (Les Mondes, Nov. 11th, 1880.)[135]
22. _Speculum Metal_, for telescope mirrors, is an alloy of copper,
tin, and 3 per cent. of arsenic.
23. In America, a paper soaked in a solution of arsenic and other drugs
is burnt, and the smoke inhaled for asthma and bronchitis. (Year Book
of Pharm., 1873, p. 345.)
24. Traces occur in mineral waters.
SULPHIDES OF ARSENIC.
_Orpiment_, As_{2} S_{3}, Auripigmentum, or King’s Yellow, trisulphide
of arsenic, obtained by precipitating a solution of arsenic with
sulphuretted hydrogen, is a yellow inodorous powder, insoluble in water
and in hydrochloric acid, but slowly oxidizing in air to arsenious
acid, and therefore poisonous. It is found native. By heat it melts
to a reddish liquid: if air be excluded, it volatilizes at about 700°
C., and condenses unchanged: if air be present, it is oxidized to
sulphur dioxide and arsenic trioxide, which condenses in the crystals
before-mentioned. It is soluble in alkalies and their carbonates,
and reprecipitated by hydrochloric acid. Commercial “King’s Yellow,”
formerly used as a pigment, but now replaced by Chromate of lead, is
a very poisonous mixture of As_{2} O_{3} and As_{2} S_{3}. It is
sometimes employed in printing indigo. A mixture of orpiment, water and
lime is used in the East as “Rasma” (see page 320) for a depilatory.
In a corpse, by putrefaction, the arsenic is frequently converted into
sulphide.
_Realgar_, the disulphide, As_{2} S_{2}, is red, exists as a mineral,
and is also made artificially for fireworks. It contains _about_ 75 per
cent. of arsenic, but varies. Formerly it was used as a pigment, and in
tanning to remove hair.
These sulphides have rarely been used for criminal purposes. _Orpiment_
was employed by Mary Ann Burdock, 1833.[136] Being insoluble, they
would only be absorbed after oxidation into As_{2} O_{3}. Ossikovszky
(J. Pract. Chem. 2, xxii., 323) finds that this change happens
rapidly in contact with organic bodies. But the opposite change, by
putrefaction and development of sulphuretted hydrogen, of As_{2} O_{3}
into As_{2} S_{3}, is far more likely and frequent.
ARSENIC ACID
is obtained by oxidizing As_{2} O_{3} by nitric acid. It is a white
deliquescent solid, inodorous, _very soluble in water_ to a syrupy
solution, which is corrosive, strongly acid and metallic in taste. By
heat it first gives the pentoxide, As_{2} O_{5}, then it breaks up into
As_{2} O_{3} and oxygen, finally completely volatilizing. It is said
to be less poisonous than As_{2} O_{3}. (Wöhler and Frehrichs, Ann.
Chem. Pharm., lxv., 335.)
The _arsenates_ are very like the phosphates. Like them they give
with acid molybdate solution a yellow, with magnesium sulphate a
white crystalline, precipitate. But with sulphuretted hydrogen, after
acidifying, they give _slowly_ a yellow precipitate of sulphide
of arsenic and sulphur; and with silver nitrate a _liver brown_
precipitate of silver arsenate.[137] Sulphurous acid reduces arsenic
acid to arsenious.
_Sodium arsenate_ is in the British Pharmacopœia, and is employed in
calico printing. A brominated solution of potassium arsenate (strength
= 1 per cent. As_{2} O_{3}) is used in Russia for epilepsy. “Pearson’s
solution” is 1 grain sodium arsenate to 1 oz. water. “Macquir’s neutral
arsenical salt” is a binarsenate of soda. “Papier Moure” consists of
paper soaked in solution of potassium arsenate (Tidy).
Fischer (Ber. deutsch. Chem. Gesellschaft, xiii., p. 1778) proposes
_ferrous chloride_ as better than sulphurous acid for reducing arsenic
acid to arsenious (see process for separation, post).
_Arsenic Trichloride_, As Cl_{3}, is a volatile, colourless liquid,
very pungent, and fuming in air. It has been discarded from medical
use on account of its dangerous properties. A case of poisoning by it
is mentioned in Taylor (Med. Juris. 1, p. 278). It is obtained in the
process for separation from the organs. Arsenic Triiodide, a dull red
crystalline solid, is used in ointments.
_Arseniuretted hydrogen_, As H_{3}, is a colourless gas of a garlic
odour, almost insoluble in water. It burns with a livid bluish-grey
flame, forming water and a white cloud of As_{2} O_{3}. By heating to
redness it is decomposed into hydrogen and a deposit of arsenicum (the
“mirror”). It is formed whenever hydrogen is evolved in contact with
arsenic compounds, hence has caused accidents in making hydrogen from
impure zinc. It is probably the most deadly compound of As, and proved
fatal to its investigator, Gehlen, and in several other cases.
EXTRACTION AND TESTS.
If arsenic has been given in the solid form, the greater part will
remain insoluble, and will be found either in lumps or powder in the
stomach, or as a white powder adhering to its lining. Any substance so
found should be washed with water and tested for arsenic. It is absurd
to say, as Dr. Letheby did in Ann Merritt’s case (_ante_, p. 366), that
the quantity was too small for examination: if a white powder can be
_seen_, it can be _tested_. In the contents, or in any fluid food, the
heaviness of powdered arsenic will cause it to readily separate as a
sediment. Soot or indigo, the legal admixtures, should also be sought.
Arsenic is not naturally present in the body (Sonnenschein,
Gerichtlich. Chemie, p. 122; and others). As it occurs in soils, in
cases of disinterment a portion of the earth surrounding the coffin
should be tested.[138]
When absorbed, it may pass into every part of the body, but more
especially into the liver and spleen. De Poncy and Livon have
supposed that it was capable of replacing phosphorus in the actual
brain substance (Comptes Rendus, 23, June 9th, 1879), and that it is
mainly localized in the _brain_. Another author finds it concentrated
in the _bones_. Prof. E. Ludwig of Vienna, in the case of a woman
who suffered from making artificial flowers coloured with magenta
containing arsenic, found arsenic in the liver, spleen, kidneys, and
stomach, but not in the bones or urine (Lond. Med. Record, Dec. 15th,
1877, p. 509). He found also that in human beings as well as dogs
poisoned with arsenic, in both acute and chronic cases, the liver
contained the largest amount, the kidneys sometimes a considerable
quantity, and the bones, brain and urine, only small traces (Jahresb.
für Thierchemie, 1879, 85). These results have been discussed by
Johnson and Chittenden (American Chem. Journal, 2, 332), who, in a
woman poisoned by arsenic, found, _a year and a half after burial_,
over 5 grains of As_{2} O_{3}, almost evenly distributed. The
conclusion to be drawn is, that, of the absorbed arsenic, the main
part will be in the liver, and the rest in varying proportions in
other tissues, so that as much as possible of the whole body should be
examined.
As the large quantity of organic matter is in the way of the tests, it
has been proposed to get rid of this by different processes. That of
Fresenius and V. Babo consists in oxidizing the substances by strong
hydrochloric acid and chlorate of potash. There is a great objection
to this, as loss is liable to occur from volatilization of arsenic
trichloride, unless it is done in a retort, which is practically
impossible on account of the bulk and frothing, and the danger of
explosion from the oxides of chlorine formed.
The following modification of an old process has been found by the
author to be satisfactory. It may be used also for antimony and
mercury. Weigh the whole, cut up finely, and grind the matters to
a pulp with water, reserving a weighed portion of about one third;
render strongly alkaline with potash or soda previously tested
for arsenic. Pass in a current of chlorine, _stopping before the
alkalinity is destroyed_. Boil the solution down to a low bulk, _not
to dryness_, till a portion taken out and treated with acetic acid
gives no chlorinous odour, showing that the hypochlorite has been
completely decomposed. Arsenic trichloride does not escape from
alkaline solutions, so there is no loss. Add sufficient _pure_ aqueous
sulphurous acid, to reduce the arsenic acid to arsenious. Now transfer
to a large retort provided with a tube-funnel and condenser, the
end dipping into water in a well-cooled tubulated receiver, itself
connected by a tube with a flask containing dilute potash solution.
Through the tube-funnel pour in pure concent. sulphuric acid in volume
about equal to the liquid, adding it gradually, as there is much heat
and effervescence. Mix well by shaking, and distil slowly from a sand
bath. In distilling a moderately strong solution of mixed arsenious
and antimonious chlorides in concent. hydrochloric acid, I have found
that the arsenic all comes over in the first third of the distillate,
and that after two-thirds have passed over, the antimony also begins
to distil. Hence, in the above process the distillation should not
be carried beyond half the volume of the liquid in the retort, when
all the arsenic, _in whatever form it originally existed_, will be
found as chloride in the receiver, except a little which may have
escaped into the potash. Test a portion of the potash solution by
Marsh’s or Reinsch’s process as hereafter described: if any arsenic
be present, add the remainder to the liquid in the receiver, taking
care that excess of free acid is left. Pass into the distillate washed
sulphuretted hydrogen in excess (or add a solution of the gas in
water), warm, cover, and allow to stand. (The excess of sulphuretted
hydrogen may afterwards be removed by warming and passing in carbonic
acid gas.) If any arsenic be present, a yellow precipitate of arsenious
sulphide, As_{2}S_{3}, will appear; if the precipitate be pale, it will
consist mainly of sulphur, formed by the action of the sulphuretted
hydrogen on the sulphurous acid which is present. Some organic matters
are also generally present. Collect the precipitate on a filter, wash
with sulphuretted hydrogen water, dissolve in a dilute solution of
ammonium carbonate, and again precipitate with hydrochloric acid. The
precipitated arsenious sulphide is now nearly pure: it may be collected
on a small filter, washed rapidly, again dissolved in ammonia, the
solution received in a porcelain dish, evaporated to a low bulk,
transferred to a weighed porcelain boat, and heated cautiously in
a current of carbon dioxide to a temperature not above 400° C.,
sufficient, in fact, just to melt the arsenious sulphide. [Sulphur
boils at 446° C., As_{2}S_{3} at 700° C.] Any remaining sulphur is thus
removed, and the arsenious sulphide may then be weighed. The weight
multiplied by 0·805 gives the amount of arsenic trioxide.
A less preferable way is to collect the arsenious sulphide on a weighed
filter, to dry, and dissolve out any sulphur by carbon disulphide. Yet
another method is to oxidize by nitric acid, evaporate, precipitate
the arsenic acid by a mixture of ammonic chloride, magnesic sulphate,
and strong ammonia —“magnesia mixture”) as ammonio-magnesic arsenate,
and weigh, either as that salt, or, after ignition, as pyroarsenate
of magnesia. The former, dried at 100° C., contains 39·57, the latter
48·29 per cent. of As. Lastly, if the sulphide, oxidized by nitric
acid, be alkalized with ammonia, and warmed to 70° or 80° C. with a
solution of ammonium molybdate in nitric acid, as used for the ordinary
determination of phosphates (see Fresenius, Qual. Anal., p. 54), a
yellow precipitate of _arsenomolybdate of ammonia_ appears, which can
be weighed: it contains 3·3 per cent. of As (Bull. Soc. Chem., Jan.
7th, 1877).
But where such importance may hang on quantities, the use of weighed
filters for such small amounts is simply courting error. When the
As_{2}S_{3} has been weighed in the porcelain boat, calculate it
into As_{2}O_{3}, or into As (it contains 61 per per cent. of As),
then cover it with a mixture of pure potassic cyanide and sodium
carbonate, place it in a piece of combustion tubing drawn out at the
end into a long thin point, pass washed dry carbon dioxide over it,
and heat cautiously till all the water is expelled. Finally raise the
temperature to full redness, and pass a _slow_ continuous current
of the gas, keeping the narrow part of the tube cool with moistened
blotting paper. The sulphide will be reduced to As, which will deposit
in a metallic coating on the narrow portion. Seal this part, and
preserve it as evidence.
It is obvious that the residue in the retort may be tested for other
metals.
The presence of arsenic ascertained, and the quantity known, it would
seem as if nothing more was necessary. Still, it is useful to confirm
results by the other tests. The reserved portion may now be divided and
used as follows:—
MARSH’S TEST.
If hydrogen be evolved in presence of arsenical compounds, it combines
with the element to form “arseniuretted hydrogen,” or _arsine_,
AsH_{3}, a colourless gas of alliaceous odour, extremely poisonous,
giving, when passed into silver nitrate solution, a precipitate of
silver and a solution of As_{2}O_{3}; decomposed at a red heat into
As and hydrogen, and burning with a livid flame into As_{2}O_{3} and
water. The flame yields, when a cold surface, such as a porcelain
crucible-lid or dish, is depressed into it, a steel-grey lustrous stain
or ring of metallic arsenic.
To evolve the hydrogen, Marsh originally used zinc and sulphuric acid.
As it is so difficult to obtain zinc pure, magnesium has been proposed.
But the evolution is then too rapid. Moreover, the reputed “pure”
acids of commerce are scarcely ever free from a trace of arsenic. This
difficulty affects equally the galvanic method. Hence it is better to
employ _sodium amalgam_ (Edmund Davy, Chem. News, xxxiii., 58, and
ditto, 94). One part of sodium, scraped free from oxide, is melted
under solid paraffin, and gradually added to ten parts of mercury
(previously purified by nitric acid) with constant stirring, the
paraffin poured off, and the amalgam cleaned by washing with pure dry
benzine. The result is a solid crystalline alloy.
A few fragments of this alloy are placed with water in a flask provided
with a thistle funnel, and with a delivery tube dipping into a 4 per
cent. solution of silver nitrate. The horizontal part of the delivery
tube is heated to just below redness by a lamp, meanwhile being
supported to prevent its bending. If, after about an hour, no As ring
appears in the tube, and if the silver nitrate, after precipitation
of the silver by hydrochloric acid and filtration, gives no arsenious
sulphide on addition of sulphuretted hydrogen, the amalgam is pure.
Now add to the flask the suspected liquid, put in more amalgam, and
continue the heating of the tube and passing of the hydrogen till
no further evolution of As occurs. The portion of tube containing
the deposit of As may be cut off, weighed, the As dissolved off
by aqua regia, and the tube washed, dried, and weighed again. The
silver nitrate solution contains the remainder of the As dissolved
as As_{2}O_{3}: after removal of the silver by hydrochloric acid and
filtration, the arsenious acid solution may be divided, a portion
titrated by iodine (see Blyth’s Pract. Chem., p. 392), and the rest
tested qualitatively by sulphuretted hydrogen, ammonio-silver nitrate,
and ammonio-cupric sulphate (see these tests, _post_).
If the original liquid be rendered strongly alkaline before adding
the amalgam, no antimony will pass off with the arsenic. But from
_acid_ liquids, arsenic and antimony pass off together. They both give
metallic rings in the tube, and stains on a cold surface. The chief
distinctions between them are as follows:—
1. _Arsenic._—More volatile, hence deposited further from the flame;
bounded by a “hair brown” fringe of suboxide; heated in a current of
sulphuretted hydrogen gives _yellow_ As_{2}S_{3}, unchanged by passing
dry hydrochloric acid gas: heated in air, it gives easily a sublimate
of As_{2}O_{3} in glistening octahedral crystals. It is soluble at once
in chloride of lime solution.
2. _Antimony._—Less volatile, hence forming close to the flame; no
brown fringe; heated in a current of sulphuretted hydrogen, gives
_orange or black_ Sb_{2}S_{3}, volatilized by passing dry hydrochloric
acid; heated in air, it gives a white oxide, volatile with great
difficulty, and not generally crystalline. It is insoluble in chloride
of lime solution.
By the above process, Edmund Davy has detected one-millionth of a grain
of As; 1/1000 grain gives a very decided effect in a few minutes. It
is applicable not only to As_{2}O_{3}, but to all other arsenical
compounds in powder, whether soluble or insoluble. Organic matter
interferes very little.
It must be observed that hydrogen alone may give a slight reduction and
precipitate in solutions of silver nitrate.
To prepare pure sulphuric acid and pure zinc, see Selmi, Chem. Soc.
Journal, May, 1881, p. 311.
REINSCH’S TEST.
If a fragment of pure copper be boiled with _pure_ hydrochloric acid
for ten minutes, no discolouration occurs. If now a solution containing
arsenic be added, the copper turns black or grey, from formation of an
alloy of copper and arsenicum. On drying the copper, and heating it
in a small glass tube closed at one end, the arsenicum is oxidized,
with production of crystals of As_{2} O_{3}. Organic matter does not
interfere. _Antimony_, sulphides, and some metals produce a similar
grey deposit, but do not yield a _crystalline_ sublimate. _Mercury_
also precipitates on the copper, but the sublimate consists of metallic
globules.
Any compound of arsenicum, mixed with dried potassium cyanide and
carbonate of soda, introduced into a piece of hard glass tubing drawn
to a point, and heated in a slow stream of dry carbon dioxide, gives
a deposit, in the narrow portion, of the whole of its arsenic in the
metallic form (Fresenius).
As_{2} O_{3} heated in a tube with dry potassium or sodium acetate
gives _cacodyl-oxide_ (Bunsen) of an exceedingly offensive alliaceous
odour.
In solution, arsenious acid gives:—
1. _With ammonio-silver nitrate_ (prepared by adding silver nitrate to
dilute ammonia till a precipitate just forms) a _yellow_ precipitate of
silver arsenite, soluble in ammonia and in nitric acid.
2. _With ammonio-cupric sulphate_ (prepared by similarly treating
cupric sulphate), a _bright green_ precipitate of cupric arsenite.
3. With _sulphuretted hydrogen_ a yellow colour (the intensity of this
has been proposed as a method of estimating small quantities of arsenic
by comparison _à la_ Nessler), but no precipitate till hydrochloric or
other acid be added, when _yellow arsenious sulphide_ falls. This is a
most delicate test, as arsenious sulphide is only soluble to the extent
of one part in one million of water (Fresenius, Quant. Anal. p. 137),
and not much more soluble in acids. The precipitate may be weighed, or
treated as already mentioned (pp. 386-7). Tin and cadmium solutions
also give yellow sulphides, but they are insoluble in ammonia, and do
not yield the other tests.
4. Stannous chloride (protochloride of tin) gives a brown deposit of
metallic arsenic. With acids containing traces of arsenic it gives a
brown colour.
DOSES.
1. _Medicinal_ (British Pharmacopœia).—Acidum arseniosum (As_{2}
O_{3}), 1/60 to 1/12 grain in solution. Liquor arsenicalis (solution of
potassium arsenite), 2 to 8 minims. Liquor arsenicalis hydrochloricus
(solution of chloride of arsenic), 2 to 8 minims. Sodæ arsenias (sodium
arsenate), 1/16 to ⅛ grain. Liquor sodæ arseniatis (solution of the
preceding), 5 to 10 minims. Ferri arsenias (ferric arsenate), 1/16 to ½
grain.
2. _Poisonous._—Smallest recorded: _one grain_, (Lancet, Dec. 16th,
1837), _two grains_, (Provincial Journal, 1848, p. 347); average
smallest, 2½ grains. Recoveries have been described after enormous
doses, up to 1½ ounce, taken solid and therefore not dissolved,
rejected by vomiting or purging, or prevented from irritant action by
abundance of food (see a case in the Lancet, Jan. 13th, 1849, when 1oz.
was taken with recovery).[139]
Idiosyncrasy may cause smaller doses to be dangerous; on the other
hand, habit may cause tolerance of the poison, as already mentioned
with regard to arsenic eaters. Nitre is said to increase the poisonous
action (Med. Times, 1844, p. 216). Antimony by its prostrating action
would have the same effect.
PHYSIOLOGICAL EFFECTS.
The symptoms usually commence in ½ to 1 hour after administration
(Taylor), but vary with dose, form, &c. They have also been _immediate_
(case of Lofthouse, York, 1835); in ten minutes (Guy and Ferrier); in ¼
hour (Taylor); in 5, 7, 8, and 10 hours (Med. Gaz. xlvii. 722); in 23
hours (Med. Times, Oct. 21, 1848); in _four days_ (Woodman and Tidy,
Forens. Med. p. 134).
As to the character of the symptoms, _irritation of the stomach and
intestines_ is the main feature. Burning pain, vomiting and purging,
cramps and occasionally tetanus (Orfila, i., 449) occur. Rarely there
is insensibility and no pain. Great thirst, constriction of the throat,
headache, and finally exhaustion are common. Sometimes epilepsy
or paralysis has been caused. The truth is, that every variety of
constitutional disturbance may be caused by the violent irritation of
the alimentary canal, except that the intellect is rarely affected.
In many cases the effects closely resemble those of acute diarrhœa or
English Cholera. One anomalous case is on record when death occurred in
four hours after sound sleep, and _no inflammation_ of the stomach was
found (Lancet, xii., 194). For a detailed list of cases, see Guy and
Ferrier’s Forens. Med. p. 457.
_Fatal period._—Shortest, twenty minutes (Taylor); average, about
twenty-four hours. Death in three to eight hours is common. But the end
has been sometimes far more protracted, even to _two years_ (_Ibid._,
Med. Jur. i., 256).
The _vomit_ is usually yellowish (L’Angelier) from bile: occasionally
it is tinged with blood; rarely white. If the arsenic has been mixed
with soot or indigo, these will affect its colour.
_Post Mortem Appearances._—The lining membrane of the stomach and
intestines is almost always inflamed and reddened, rarely darker from
congestion. White patches, covered with mucus, should be examined
for solid arsenic. Perforation, ulceration, and gangrene are rare.
In bodies long buried, the arsenic is often converted into sulphide
by putrefaction, and then appears as a yellow coating. Occasionally
inflammatory appearances are found in the mouth, throat and other
organs. Congestion of the brain is uncommon.
Among the effects of _chronic_ poisoning by arsenic may be noted
inflammation of the eyelids (conjunctivitis), skin eruptions,
irritability of the stomach, jaundice, and local paralysis (for cases
see Taylor’s Med. Jur., i. 252).
TREATMENT AND ANTIDOTES.
Vomiting should be encouraged by emetics or tickling the throat; the
stomach pump being used if judicious. To obviate the irritation,
demulcents such as arrowroot, mucilage, &c., are useful. Albumen
(white of egg) has proved serviceable (Lancet, Jan. 13th, 1849). To
render the arsenic insoluble, magnesia or chalk may be given. But the
best chemical antidote is hydrated ferric oxide, freshly prepared
by precipitating ferric chloride or tinct. ferri sesquichlor. with
carbonate of soda (washing soda), or by similarly precipitating ferrous
sulphate (copperas), and then shaking the mixture with air till it
turns red, or by the following formula:—
Tinct. ferr. perchlor. 1 oz.
Sod. bicarb. 1 oz.
Tepid water, a teacupful.
(Hoglan, Year Book of Pharm. 1881, p. 211).
M. Lucas of Beauvais has stated, that in nine cases of arsenical
poisoning, calcined magnesia arrested the symptoms and eventually
removed the effects (J. Chim. Medi. 1850).
REMARKS.
Arsenic has been given in pessaries by the vagina, in ointment for skin
diseases and by “cancer doctors,” also inhaled as vapour for asthma,
in each case with dangerous result.
The frequent occurrence of this poison in common articles of use gives
an opportunity to the defence which has led to analyses of multitudes
of articles—wall-papers, clothing, cooking vessels, &c. It may be
positively affirmed that if white arsenic _in the solid state_ be found
in the stomach, it could not have come from any of these sources. The
trace that could be derived from wall-papers would be infinitesimal.
The tests for arsenic are almost inconveniently delicate, so that
the slightest impurity of the reagents will make it appear to be
present. Reichardt (Archiv. der Pharm., xiv. 1-23), states that 1/1000
milligramme of As_{2}O_{3} evolved as arseniuretted hydrogen will
precipitate silver nitrate, and that by this means he has found it in
the urine of patients suffering from arsenical wall-papers. The effect
of such papers is certainly pernicious, though it may be mentioned that
in Silesia mortar is made with arsenical sand, and people living in
houses thus built do not suffer (Lancet, 1849, April 7th). On the whole
it may be concluded that in a trial, _traces_ of arsenic will not be
sufficient, a tangible quantity found and _weighed_ will be the only
sufficient evidence of poisoning by the mouth.
To illustrate the value of a knowledge of chemistry to a medical man in
such cases the following may be quoted. A child of ten was supposed to
have eaten a quantity of meal mixed with arsenic for rats. An emetic of
sulphate of zinc was given: the first vomit gave with ammon. sulphate
of copper a bright green, with ammon. nitrate of silver, a yellow
precipitate, thus establishing that the poison was arsenic. Emetics and
diluents were continued, then albumen was given. Some hydrated ferric
oxide was hurriedly made from common green vitriol (ferrous sulphate)
and ammonia: the washed precipitate was administered in successive
teaspoonfuls. Recovery on the third day. In the vomit 10 grains of
white arsenic were found. (Lancet, 1849, p. 311.)
The following is a curious form of attempted poisoning. A person lately
presented this prescription in Paris: “Decoct. barley, 8 oz.; hydroch.
acid, 1 drachm; _arsenious acid, 10 grains_.” The signature of a
physician was appended, but, on suspicion being aroused, was found to
be a forgery.
In Ann Merritt’s case, Dr. Letheby stated that arsenic had been taken
not more than two or three hours (afterwards he said four) before
death, because he found undigested gruel in the stomach, containing
arsenic _in solution_, and because the intestines contained very little
arsenic. This conclusion was considered by weighty authorities to be
rash, and probably wrong, because:—
1. He found 2 grains (a poisonous dose) in the liver. This could hardly
have got there within so short a time.
2. In a stomach irritated by arsenic or disease, food may remain
undigested for seven, eight, or more hours.
8. A previous dose of arsenic, adherent to the coats of the stomach,
might be dissolved by an influx of warm gruel.
4. The portion in the intestines might have been evacuated by purging.
5. The “pinkish liquid” described by the surgeon who performed
the _post-mortem_, pointed to admixture with blood, therefore to
inflammation of some standing, and certainly did not tally with Dr.
Letheby’s description of “gruel.”
With reference to the alleged administration of arsenic in cocoa in
Madeline Smith’s case, the following details will be illustrative.
100 grains of white arsenic were found to be a small teaspoonful,
not heaped. This quantity was mixed with two teaspoonfuls of Epps’s
cocoa. The colour was rendered lighter, but still looked natural. On
making up with boiling water and milk, as directed, a cup of cocoa
was obtained, in which neither appearance, taste, nor smell, betrayed
anything unusual. On standing the milk rapidly curdled, and the arsenic
deposited, but this would not be seen in an opaque cup. With arrowroot
or gruel a similar result was obtained.[140]
It has been stated that arsenic trioxide volatilizes with the vapour of
water. I have not found this to be the case to any appreciable extent,
but it does volatilize slowly at 100° C., and still more at 120°. About
½ gramme of As_{2} O_{3} lost, after six hours on the water-bath, 3 per
cent. of its weight; after six hours at 120° C. it lost six per cent.
When chlorides are present, as in the body, it is still more liable
to volatilization as arsenic trichloride. Hence matters containing
it cannot be boiled down or dried without danger of loss, unless
previously rendered alkaline.
R. Otto has stated that ordinary sulphuretted hydrogen may contain
arsenic from the sulphate of iron used. He proposes to prepare the
gas by the action of pure hydrochloric acid on pure calcium sulphide
obtained by roasting gypsum with charcoal (Ber. Chem. Ges. xii. 250). I
have tested water into which sulphuretted hydrogen has been repeatedly
passed, and have found no arsenic: if really present in the gas, the As
H_{3} is not absorbed in the liquid.