ANTIMONY.
Properties of the metal—Alloys—Compounds—Chlorides, sulphides,
oxides, hydride. Tartar emetic—solubility, composition, uses
and occurrence—commercial, veterinary, medicinal. Doses
and preparations—fatal dose, fatal period. Physiological
effects—Antidotes—Separations and tests—(1) Reinsch’s—Presence of
antimony; purity of the copper employed, how to be secured; different
stains resulting from presence of arsenic, antimony, mercury, bismuth,
tin, silver, gold, platinum, palladium, sulphur compounds—(2) Dr.
Maclagan’s test in Pritchard’s trial—(3) Marsh’s test—Remarks
on Pritchard’s trial—On Smethurst’s trial—Dr. Taylor and Mr.
Herapath—Arsenic in bismuth—Antimony in grey powder.
ANTIMONY.
THE metal antimony (symbol Sb, from its classical name _Stibium_)
is heavier than arsenic (sp. gr. 6·8), less easily tarnished, more
difficult to pulverize, and not nearly so volatile. It forms somewhat
brittle masses, with a fern-like crystalline appearance on the surface.
When broken the interior shows radiating (rhombohedral) crystals of a
bluish-white, strongly metallic lustre (arsenicum is greyish, bismuth
is pinkish, white), yielding a grey or black powder. Melting point,
425° C. Heated with the blowpipe on charcoal it gives white fumes of
oxide, _without odour_ (arsenic gives a garlic odour). The metal is
insoluble in water and dilute acids, but soluble in _aqua regia_ to
form antimonious chloride; also soluble in sulphide of potassium or
sodium. Hot concent. sulphuric acid converts it into sulphate. Nitric
acid turns it into a white powder consisting chiefly of _metantimonic
acid_, HSbO_{3}, of which a small quantity dissolves.[188] The
powdered metal burns in chlorine, forming Sb Cl_{3}, or Sb Cl_{5}.
Metallic antimony is obtained as a “mirror” in Marsh’s test: the
distinctions between it and arsenic have been already given (p. 389).
The following is the percentage of metallic antimony in different
alloys. English type metal, 20 to 25; German ditto, 15; Britannia
metal, 10 to 16; pewter, 7; Argentine, 14½; Ashbury metal, 19½; white
or anti-friction metal for engine-bearings, 10; Babbit’s metal, for
similar purposes, 13; alloy for ships’ nails, 17 (Ure’s Dictionary, I.,
169; Roscoe and Schorlemmer’s Chemistry, 1880, ii., 2, p. 307). There
is also antimony in brass, metallic mirrors, bell-metal, &c. (Blyth).
_Antimony black_, used for giving a steel-like lustre to plaster casts,
is finely divided Sb, precipitated from the chloride by zinc.
Metallic antimony is not poisonous unless partially oxidized.
Commercial samples usually contain a little arsenic, which enters into
the salts.
_Antimonious chloride_, Sb Cl_{3}, when pure, forms colourless
glistening deliquescent crystals. A solution in hydrochloric acid
constitutes the commercial “butter of antimony” used for giving a dark
bronzing to brass. It is a thick, powerfully acid liquid, coloured
brown by the presence of iron, fuming in air, very corrosive, and
of an irritating odour, distilling over at about 200° C. (_pure_ Sb
Cl_{3} boils at 223° C.), decomposed by water into a white magma of
_oxychloride_, Sb O Cl, “powder of Algaroth” (tartar emetic is not
decomposed by water). It is a violent corrosive poison, blackening and
destroying the surfaces like oil of vitriol. For cases, _see_ Woodman
and Tidy, p. 130.
_Antimonic chloride_, Sb Cl_{5}, is rarely met with. It resembles Sb
Cl_{3}, but is liquid.
_Antimonious sulphide_, Sb_{2} S_{3}, is found native as “stibnite,”
“speiss-glas,” “grey antimony,” or “antimony glance,” sp. gr. 4·63, in
lead-grey striated prisms, fibrous or massive, of a strong metallic
lustre, fusing readily to a dark-brown glass —“vitrum antimonii”),
giving before the blowpipe white fumes, and an odour of sulphur
dioxide —“brimstone”). It is the principal ore, the source of all the
preparations, and is itself used in fireworks. When powdered it is
black, and in this state was used by the Roman ladies under the name of
“stibium,” by the Orientals as “Kohl,” for darkening the eyelids. It
is soluble in hot hydrochloric acid to form SbCl_{3}. The precipitated
sulphide is orange, and will be noticed under the tests. Sb_{2} S_{3}
would not be poisonous until oxidized.
_Antimonious oxide_, Sb_{2} O_{3}, obtained by burning Sb in air, is a
white powder, turned yellow on heating, soluble in hydrochloric acid to
form Sb Cl_{3}, and in cream of tartar (acid potass. tartrate) to form
_tartar emetic_. Unlike As_{2} O_{3}, it does not easily volatilize in
crystals. It is occasionally found native.
_Antimonic oxide_, Sb_{2} O_{5}, is a pale yellow powder. There is also
an intermediate oxide, Sb_{2} O_{4}.
_Antimonious and antimonic acids_ are hydrates of the above oxides.
They exist in several modifications, and form metallic salts, one of
which, sodium pyrantimonate, Na_{2} H_{2} Sb_{2} O_{7}, 6 H_{2} O, is
the only known insoluble salt of sodium, and hence available as a test.
_Antimonious hydride_, Stibine, or “antimoniuretted hydrogen,” Sb
H_{3}, has never been obtained pure. In admixture with hydrogen,
as given by Marsh’s test, it is a colourless gas, almost or quite
_inodorous_ (distinction from As H_{3} which smells like garlic),
decomposed by heat into hydrogen and a “mirror” of Sb. Its poisonous
properties have been doubted, but it is probably more dangerous than
As H_{3}, on account of the absence of the warning odour. It burns
with a bluish-green flame, giving white clouds of Sb_{2} O_{3}, and a
spot of Sb, duller and greyer than As, when a cold porcelain surface
is depressed into the flame. Passed into silver nitrate solution, the
Sb is precipitated along with metallic silver as _silver antimonide_,
Ag_{3} Sb, whereas arsenic under the same circumstances would remain in
solution as As_{2} O_{3}.
TARTAR EMETIC.
_Potassio-antimonyl tartrate_, _tartrate of antimony and potash_,
“_antimonium tartarizatum_,” “_tartarized antimony_,” “_stibiated
tartar_,” symbol K (Sb O) C_{4} H_{4} O_{6}, ½ H_{2} O, occurs in
colourless rhombic octahedral crystals, transparent at first, but
becoming opaque by efflorescence, or as a white powder, inodorous, and
with a strong metallic taste. The aqueous solution is faintly acid to
test-paper, and becomes mouldy on keeping. When evaporated on a glass
slide, it leaves a crystalline residue of _tetrahedra_, cubes and
branching forms. (_See_ figure in Guy and Ferrier’s For. Med., p. 469.)
Heated on platinum, tartar emetic blackens and swells up with an odour
of burnt sugar (due to the tartaric acid), gives a bluish-green tint
to the flame, and quickly fuses and makes a hole in the platinum, from
the formation of a fusible alloy. Heated in a closed tube, it gives
charcoal, potass. carbonate, and metallic antimony, which does not
sublime at a moderate temperature, is inodorous, and may be separated
in metallic globules by washing (differences from arsenic; _see_ p.
389). Sulph. hydrogen of course gives the orange-red sulphide.
_Solubility._—Tartar emetic is almost insoluble in alcohol, and still
less soluble in ether, chloroform, &c. Spirits and water, such as
are mixed for drinking, dissolve nearly as much as cold water, and
more if warm. The solubility in cold water is given very variously in
the text-books, from 1 part in 21·8 —“20 grains per fluid ounce,”
British Pharmacopœia), 1 in 20 (Garrod and Blyth), 1 in 15 (Brande’s
and Gmelin’s Chemistry), to 1 in 14 (Graham and Taylor). To clear up
this difficulty I prepared for Dr. Bernays in 1879 a very pure sample
of the salt: he found that 100 cubic centimetres of water at 58° F.
dissolved 6·67 grammes, equal to _one part in fifteen_. The solubility
rises rapidly with the temperature, till it reaches _one part in two_
at the boiling point. The discrepancies are accounted for by the facts
that, (1), the textbooks do not mention the temperature; (2), the salt
readily effloresces in air, losing water and becoming less soluble;
(3), impurities are often present.
_Composition._—Commercial tartar emetic is generally very pure. It
sometimes contains a trace of sand and dirt, occasionally an excess of
cream of tartar (potass. hydrogen tartrate) from careless preparation,
but I have never found arsenic. The theoretical percentage of Sb is
36·53: in good commercial samples Bernays found 36·03 to 36·32 per
cent.; in an over-dried specimen, 37·4 per cent. One sample contained
23 per cent. of cream of tartar and only 28·13 of Sb; another, 10 per
cent. tartar and 32·7 of Sb.
USES AND OCCURRENCE.
The alloys and pyrotechnic uses have been already mentioned. The impure
fused sulphide (vitrum antimonii) is employed to give a yellow tint to
glass and porcelain. The oxides are used in glazing earthenware, and
in glass and china painting. The following are antimonial pigments:
“Antimony cinnabar,” and “crocus,” or “saffron of antimony,” are
oxysulphides: “Naples,” “Cassell,” and “antimony yellows,” are chiefly
antimoniates of lead. Small quantities of antimony occur in iron ores,
ferruginous waters, the coal formation, and in river sand (Roscoe).
In _veterinary practice_, large doses of antimonials are given to
animals, as much as 90 grains of tartar emetic being often administered
to a horse in his gruel three times a day. Other preparations are used
(_see_ Blyth’s Pract. Chem. 1879, p. 404). They are supposed to cause
fattening.
_Medicinally_ it is employed in typhus, _delirium tremens_, small
doses in croup and the broncho-pneumonia of children, as a general
expectorant in asthma and bronchitis, in whooping-cough, by some
recommended also in scaly skin affections. In acute inflammations
and pneumonia, it has lost favour, as too depressing (Farquharson’s
Therapeutics). In times before chloroform, tartar emetic was even used
to lower the muscular tension previous to reducing dislocations.
DOSES AND PREPARATIONS.
_Pulvis antimonialis_, 3 to 10 grains. This is the Pharmacopœial
equivalent of “James’s Powder,” a secret remedy once highly popular. It
contains one part of Sb_{2} O_{3} to two of phosphate of lime.
_Vinum antimoniale_, antimonial wine, is a solution of 10 grains of
tartar emetic to each ounce of sherry: dose, 5 minims to 1 fluid drachm.
_Antimonii oxidum_, Sb_{2} O_{3}, is often very impure. It may
contain, (1), higher oxides of Sb, when it is not completely soluble
on boiling with water and cream of tartar; (2), carbonate of lime,
when it effervesces with acids and contains less Sb; (3), traces of
arsenic, when it gives a garlic odour before the blowpipe on charcoal.
Percentage of Sb, 83·56: dose, 1 to 4 grains.
_Antimonium sulphuratum_, or _oxysulphuretum_, is precipitated Sb_{2}
S_{3} with a small amount of Sb_{2} O_{3}. It contains about 62 to
65 per cent. Sb (pure Sb_{2} S_{3} has 70·2 per cent.). Dose, 1 to 5
grains, but rarely prescribed, except in “compound calomel pill,” _pil.
hydrarg. subchlorid. co._, which contains 20 per cent. of Sb_{2} S_{3}.
_Antimonii chloridi liquor_, a solution of Sb Cl_{3} in hydrochloric
acid, is sometimes used as a caustic, never internally.
_Antimonium tartaratum_, tartar emetic: dose, as a diaphoretic, 1/16
to ⅙ grain; as a depressant, ⅙ to 1 grain; as an emetic, 1 to 2 grains
(to 3 grains, Farquharson). It should never be used as an emetic in
suspected poisoning, as its presence would confuse the investigation.
_Unguentum antimonii tartarati_, antimonial ointment, contains 20 per
cent. of tartar emetic.
The following proprietary pills contain tartar emetic in the annexed
proportion per pill weighing about 3 grains:—_Dr. J. Johnson’s_, 0·04
grain; _Mitchell’s_, 0·05 grain: _Dixon’s_, 0·06 grain (Blyth).
It has been stated that the liqueur _absinthe_ owes its deleterious
effects to antimony. I have tested several specimens, but never found
antimony, though traces of lead or copper were occasionally present.
_Fatal dose._—About this, nothing can be exactly stated. The smallest
was, in a child, ¾ grain; in an adult, 2 grains; but in this instance
there were circumstances which favoured the fatal operation (Taylor,
Med. Jur. i., 310).
If vomiting and purging happen, the poison is for the most part
expelled: except for the effects of exhaustion, there may then be
hardly a limit to the amount which may pass in and pass out. Taylor
records recoveries from 120 grains, 200 grains, and even _half an
ounce_ of tartar emetic. In pneumonia it has been given in repeated
doses of 2 grains without ill effects. It must be remembered that, in
the hands of the poisoner, its perverted use is, not to kill, but to so
weaken the vital powers that a small and not suspicious dose of some
other poison may complete the death.
_Fatal period._—Shortest, seven hours in an adult female (Wormley);
eight hours in a boy after 10 grains tartar emetic (Lancet, 1846, p.
460). Usually much longer: four days after 40 grains (Orfila, i., 480);
up to one year from after effects (Guy and Ferrier).
PHYSIOLOGICAL EFFECTS.
The unpleasant metallic taste, the heat in the throat, and burning in
the stomach, have been described in the previously reported trials,
and in other cases. Afterwards there is nausea, severe vomiting,
profuse watery purging, often convulsions which are sometimes tetanic
in character; the skin is generally cold and clammy with perspiration;
there is collapse from exhaustion, and occasionally delirium and
insensibility. Death may happen either during the convulsions, or
during the collapse. The heat and constriction in the throat is not
invariably present.
After death there is generally found inflammation of the stomach and
intestines, especially the cæcum: the brain is sometimes congested,
the throat rarely affected. The stomach-contents are usually tinged
with blood, as with most irritant poisons.
In smaller doses it acts at first as a sedative on the brain; the
action of the heart becomes slower, weaker, and finally irregular,
the pulse is soft, the breathing slower; there is an increased
bronchial secretion, and general muscular relaxation. As an emetic
it is sluggish and depressing, and is often followed by diarrhœa. It
powerfully promotes perspiration, and is therefore used in influenza,
&c. Poisonous doses may cause paralysis, prostration, degeneration of
the liver and other organs (_see_ Taylor’s remark about the geese at
Strasburg, p. 464), inflammation and even ulceration of the intestines
(Farquharson and others).
ANTIDOTES.
Sometimes vomiting does not occur: in this case it should be promoted
by tickling the throat, and by draughts of warm water. _Tannin_
precipitates compounds of antimonious oxide (Sb_{2} O_{3}), but not
those of antimonic oxide (Sb_{2} O_{5}): as the former are the ones
almost invariably used, astringent preparations, such as strong
tea, coffee, decoction of oak bark, galls, tincture of catechu or
kino, should be given. Tannin, or tannic acid, is commonly kept by
photographers. Failing this, sodium carbonate (washing soda), in not
too strong solution, may do good. Opium to allay the irritation, and
brandy to overcome the depression, should then be tried.
SEPARATION AND TESTS.
During life, antimony may be found in the urine and fæces: after death,
if its administration has been long continued, it will be found in all
parts of the body, but especially in the _liver and spleen_. If the
doses have been discontinued some time before death, none may be left
in the stomach and intestines.
The enquiry divides itself into three parts: 1st, the _presence_ of
antimony; 2nd, the preparation used; 3rd, the quantity.
I. PRESENCE OF ANTIMONY.
Marsh’s and Reinsch’s tests have been mentioned under arsenic. It,
however, will be necessary to add a few observations on their special
use for Sb.
A fractional part, say one-fourth, of the suspected matter, after
mincing or pounding, is digested with hot distilled water containing
5 per cent. of _pure_ hydrochloric, and a little tartaric, acids,
well shaken or stirred in a covered or closed vessel, and after some
hours filtered. To a portion of the filtrate is added a little more
hydrochloric and a little sulphuric acid (to reduce the higher oxides
of As and Sb), and the whole is boiled for ten minutes. A portion of
the filtrate is now subjected to
_Reinsch’s Test._—First it is absolutely necessary to have _pure
copper_; so pure, in fact, that a quantity, _larger than would be used
in testing_, will not, _if totally dissolved up_, yield any As or Sb to
another piece of copper boiled in the solution.
Dr. Taylor’s mistake in the case of Smethurst, more fully treated of
hereafter, was a very natural one. The trace of arsenic in his copper
would not have affected the conclusion in ordinary cases: but it would
be better not to test at all than to use materials which are not
_proved beforehand_ to be free from the poison we are seeking. Pure
“electrotype” copper can now be purchased; or it can be made pure by
either of the following methods.
(_a_) “Pure” commercial sulphate of copper is boiled with a slight
excess of chlorine water, then treated with dilute ammonia till a
slight permanent precipitate forms: after standing twelve hours it is
filtered (the precipitate containing iron and arsenic), acidulated with
_pure_ sulphuric acid, and subjected to the current from two Daniell
cells, the terminals being two plates of hard wax well coated with
purified graphite: the coating must communicate with the copperwire
from the battery, and the wire must not dip into the solution. The
distance between the terminals should be so regulated that the copper
may be deposited _slowly_ and in a tough layer on the negative pole:
the thin plate so obtained may afterwards be easily detached, hammered
or rolled, and cut into suitable pieces: it is absolutely free from
arsenic.
(_b_) Pure crystallized chloride of copper is mixed with pure carbonate
of soda in excess, the mixture dried with constant stirring, heated to
near redness, powdered, mixed with an equal volume of lamp-black, and
introduced into a “plumbago” crucible lined with a paste of purified
graphite and oil. The crucible is covered, and gradually heated in
a Fletcher’s or Griffin’s gas furnace (not with coal or coke), and
finally kept at a very high temperature till the copper is reduced.
The fumes contain chlorides of copper, sodium, &c., and are poisonous.
The copper, after separation from the slag, may be cast, hammered, or
rolled, and is free from As or Sb.
I suggest these processes more for manufacturers than for chemists, but
expense and trouble should really be subordinate considerations where
life is concerned.
Now for the application. Two flasks containing pure diluted (25 per
cent.) hydrochloric acid are placed on a sandbath, and nearly closed
by small glass funnels. About a square inch of pure copper, cleaned by
sand-paper, is placed in each: to one is added the suspected liquid,
to the other an equal bulk of 5 per cent. hydrochloric acid. Both are
boiled, with occasional inspection. If the following are present, the
copper will be darkened:—
_Arsenic._—Stain _steel-grey_: dried and heated in closed tube it
gives _easily_ a sublimate of octahedral crystals of As_{2} O_{3}.
(_See_ Arsenic, _ante_.)
_Antimony._—Stain black, or in small quantity, _violet_: in the closed
tube it gives with difficulty an _amorphous_ white sublimate of Sb_{2}
O_{3}, soluble in H Cl, and then precipitated _orange_ by H_{2} S.
_Mercury._—Stain silvery: in closed tube gives a sublimate of
_metallic globules_, made more visible by rubbing them together with a
splinter of wood.
_Bismuth_, _tin_, _silver_, _gold_, _platinum_, _palladium_, &c., give
black, grey or silvery deposits, but no _sublimate_ in the tube. _Gold_
gives a stain which is _yellow_ on burnishing, and yields no sublimate.
_Sulphur compounds_ in the organic matter may give a dull stain, which
may even yield a kind of sublimate in the tube, but this sublimate will
not conform to the tests for As or Sb.
If there is much As or Sb, the deposit sometimes peels off if boiled
too long.
The process used by Prof. Maclagan in the Pritchard trial is also a
good means of verification. Boil the stained foil in a solution of
caustic potash, exposing it occasionally to the air (or boil with
a weak, slightly alkaline solution of potass, permanganate, and
filter—Odling). The Sb will be oxidized and dissolved. Add HCl and
pass H_{2} S: an orange precipitate of Sb_{2} S_{3} will prove the
presence of antimony.
If Sb has been found, remove the first piece of copper, and boil with
another piece, and so on till the Sb is all removed. The coated slips,
the sublimate, the Sb_{2} S_{3}, and the copper in the second flask
which has still remained bright, should be sealed up to be shown in
court.
The previous treatment with sulphurous acid prevents any interference
by oxidizing agents such as chlorate of potash, nitrates, iodine, &c.
_Marsh’s Test_ is more delicate, but more liable to error, than
Reinsch’s.
Two methods of applying Marsh’s test to antimony may be used.
A. By Edmund Davy’s process with sodium amalgam (_see_ Arsenic, p.
388), only As H_{3} passes off, the Sb remaining behind. Hence, when
the arsenic has finished coming over, if the remaining solution be
acidulated with _pure_ sulphuric acid,[189] _pure_ zinc put in, and
one or two drops of _pure_ platinic chloride added to facilitate the
evolution of hydrogen, the antimony will then come over as Sb H_{3}.
B. Or the original substance may be placed in the flask, treated at
once with the zinc and dilute acid, and the As H_{3} and Sb H_{3}
passed together into silver nitrate solution, and separated by
filtration as directed under arsenic. _See_ p. 389, also as to the
distinctions between the stains of Sb and As. To these add, that
metallic spots of both As and Sb are soluble in yellow ammonium
sulphide: the solutions on evaporation to dryness on the water-bath
give:
(_a_). With _arsenic_ a _yellow_ stain, soluble in ammonia, insoluble
in hydrochloric acid;
(_b_). With _antimony_ an _orange_ stain, insoluble in ammonia, soluble
in hydrochloric acid.
_Metallic antimony_ can be precipitated as a black powder from its
solutions by acidulating with hydrochloric acid and treating with
a slip of pure tin, which does not precipitate arsenic. Zinc or
electrolysis also precipitate Sb, along with copper and many other
metals. Hence this method is not available in mixtures.
_Sulphuretted hydrogen_ gives with antimonial solutions slightly
acidulated an orange-red precipitate of sulphide, insoluble in ammonia
or ammonium carbonate, soluble in ammonium sulphide, soluble in hot
strong hydrochloric acid by conversion into antimonious chloride, and
sulphuretted hydrogen: the former then gives a white precipitate with
water, the latter gives the characteristic odour and blackens lead
paper.
The reactions with sodium hydrate and sodium carbonate, are not so
clear or decisive. Potass. ferrocyanide gives no precipitate. Tannin
and tincture of galls give a yellowish white precipitate. Before the
blowpipe with sodium carbonate on charcoal, solid Sb compounds give a
grey brittle globule of the metal and a white incrustation. But there
is rarely sufficient for such a test to be of use in toxicological
work, there is also a risk of loss, and other metals give a similar
reaction.
_N.B._—_Among other substances, sulphide of antimony is frequently
added to caoutchouc in the process of vulcanising india-rubber: in all
toxicological experiments involving tests for antimony (and arsenic),
great danger of a mistake is thus attendant on the use of ordinary
vulcanised india-rubber tubing. Black unvulcanised tubing should alone
be employed._
II. PREPARATION USED.
The insoluble compounds would act very slowly as poisons and would
require very large doses, hence would be found in the solid form in the
stomach, and could be identified by appearance, by the microscope, and
by the tests, after washing and settling down.
To ascertain whether antimony was _in solution_, the liquid contents of
the stomach, after dilution with water if necessary, should be allowed
to settle, the nearly clear top layer decanted and filtered, and the
filtrate examined. The soluble compounds are:—
1. _Tartar emetic._ Solution _slightly acid_, taste metallic. On
evaporation on a glass slide _tetrahedral crystals_ are obtained. If
the solution is moderately strong, it gives a white precipitate with a
little hydrochloric acid, soluble in excess: with water it gives _no
precipitate_. Stomach generally inflamed but not corroded.
2. _Antimonious chloride_, Sb Cl_{3}. Solution _strongly acid_,
effervescing and giving a white precipitate with sodium carbonate.
Taste corrosive and powerfully metallic. On evaporation, no tetrahedra.
No precipitate with hydrochloric acid: with water a white precipitate,
re-dissolved by tartaric acid.[190] By analysis a large quantity of
_chlorine_ will be found. The stomach is corroded and often blackened
or charred.
3. _Antimonates_, _antimonites_, _sulphantimonites_, and _-ates_
(such as “Schlippe’s salt”), are rare and improbable. Antimonates
are _alkaline_, give a white precipitate with acids, and a white
crystalline one with sodium salts. Schlippe’s salt is strongly
alkaline, and gives with hydrochloric acid an orange-red precipitate of
sulphide.
III. QUANTITY.
To ascertain the amount of Sb is absolutely necessary. Marsh’s test is
not available, since a large part of the antimony is thrown down on the
zinc and remains in the generating flask. It has been proposed to wash
this off and weigh it, but other metals and impurities are present,
so that this is not practicable. Reinsch’s test has been applied
quantitatively by weighing the copper before and after the test: the
difference of weight was supposed to be the As or Sb. But the copper
may dissolve or oxidise, sulphur and other things deposit on it; so
that this method is not correct.
If antimony only is present, acidulate with hydrochloric acid, pass
sulph. hydrogen in excess, warm, filter, wash the orange hydrated
antimonious sulphide into a porcelain capsule, remove most of the
water, dry on the water bath, finally at 200°C. and weigh. 100 grains
of Sb_{2} S_{3} correspond to 85·88 of Sb_{2} O_{3}, to 196·47 of
tartar emetic, to 71·76 of Sb, to 134·41 of Sb Cl_{3}.
But in the stomach any other metal may be present, hence a process of
separation must be used. It is not generally necessary to destroy the
organic matter: if this be desired, Fresenius and v. Babo’s process,
of heating with H Cl and potass. chlorate (previously proved pure) may
be used without much danger of loss, as Sb Cl_{3} is not so volatile
as As Cl_{3}. Otherwise the solution made by pure hydrochloric and
a little tartaric acids is treated with sulphuretted hydrogen. The
precipitated sulphide may be of uncertain, though suspicious colour.
After collection on a filter and washing, it should be extracted with
dilute ammon. carbonate solution (10 per cent.): _arsenic_ only will
dissolve and will be reprecipitated as sulphide on adding an acid. The
remainder on the filter must be treated with freshly prepared ammon.
sulphide: _antimony_ and _tin_ will dissolve. If any black residue
remains on the filter, it will consist of _mercury_, _lead_, _bismuth_,
or _copper_: it should be treated with hot 25 per cent. nitric acid,
when all will dissolve except _mercuric sulphide_. We shall then have
three portions:—
1st. The _mercuric sulphide_. Wash, dry, and weigh. Then heat in
a sealed tube with dry sodium carbonate, collect the sublimate of
metallic mercury, weigh it, and preserve in a sealed tube.
2nd. The nitric acid solution containing _lead_, _bismuth_, and
_copper_. Evaporate nearly to dryness, dilute, add dilute sulphuric
acid, and a little alcohol, after standing collect and weigh the
precipitated sulphate of _lead_. Precipitate the _bismuth_ by ammon.
carbonate in excess, and the _copper_ from the filtrate by zinc or by
sulph. hydrogen. (_See_ Fresenius’ Quant. Anal. p. 411).
3rd. The ammon. sulphide solution of the _antimony_ and _tin_.
Evaporate to dryness, dissolve in hot strong hydrochloric acid, dilute,
divide into two equal portions: in _one_ throw down both metals by a
rod of _zinc_: in the other throw down only Sb by a slip of _tin_. Wash
off both precipitates, dry and weigh. The first is antimony and tin
together, the second is antimony alone (Gay Lussac). The difference is
the tin.
Usually only _some_ of these metals will be present. _Tin_ has derived
more importance lately since Hehner has proved its almost constant
presence in canned provisions.
As to the delicacy of the precipitation of antimony by zinc or
galvanism, Mohr (Toxicologie, 1876) states that a solution containing
·00005 gramme of Sb in one cub. centimetre gives a distinct reaction in
fifteen minutes. Such a solution gives with H_{2}S only a colouration,
and after a long time a faint precipitate. 1/30000 part gives with zinc
a clear reaction in one half-hour: with H_{2} S, only a colour, no
precipitate, in twelve hours. 1/40000, doubtful: 1/50000, imperceptible
with zinc: of course, nothing with H_{2} S. The reaction is only
decisive if other metals are excluded.
From the solution of Sb Cl_{3}, or tartar emetic in H Cl, _gallic acid_
throws down Sb, and not As or tin. The precipitate after washing and
drying contains 40·85 per cent. of Sb. (Chem. News, XXIV. 207, 251.)
To sum up, the decisive characters of antimony are:—
1. An orange red precip. by H_{2} S in slightly acid solutions.
2. The insolubility of this precip. in ammon. carbonate.
3. Its solubility in ammonium sulphide.
4. Its solubility in hot H Cl, with evolution of H_{2} S, and formation
of a solution of Sb Cl_{3}, which is precipitated by water and cleared
up again by tartaric acid.
REMARKS.
DR. PRITCHARD’S CASE.
In connection with the supposed administration of tartar emetic on a
piece of cheese, in Dr. Pritchard’s trial (_see_ Mr. Clark’s review
of McCleod’s evidence, p. 438), the following considerations are of
interest.
1. An exceedingly small (weighed) quantity of dry powdered tartar
emetic was sprinkled on the surface of a little piece of cheese:
although the amount of tartar emetic used was far less than that
required to induce vomiting, &c., the powder was found to be plainly
visible, and the appearance of the cheese so treated would certainly
have excited suspicion in the mind of any ordinarily observant
person. Hence it is impossible that enough tartar emetic to produce
the recorded effects should have been sprinkled externally on the
very small amounts of cheese described —“not larger than a bean”—M.
McCleod: “size of a good large pea”—M. Patterson).[191]
2. With reference to the Lord Justice Clerk’s observation, p. 439,
_note_, tartar emetic is _not_ easily dissolved, a cold saturated
aqueous solution containing only 5 per cent. of the salt (according to
the B. P., 20 grains dissolve without residue in 1 ounce of water). A
piece of cheese, the size of a bean, would weigh about ⅛ ounce. I have
found by experiment that 1 ounce cheese took up by soaking not more
than ¼ ounce water, which, from the above, could contain in solution
5 grains of tartar emetic. Hence a piece of cheese, the size of a bean,
= ¼ × ⅛ = 1/32 ounce water = ⅝ grain of tartar emetic. This amount
could not cause the symptoms described.
3. If put on in powder the poisonous salt could only be concealed
by being rubbed over with butter or oil: if soaked in a solution of
tartar emetic, the cheese, in order to avert suspicion, must be wiped
or dried—operations practically impossible at the table with so many
present.
Two possibilities remain: (_a_) Cheese is often eaten with salt. Dr.
Pritchard may have had a little salt-cellar by his side, professedly
for his own use, containing tartar emetic, either alone or mixed with
salt. He may have placed a spoonful of this on the plate with the
cheese: the latter may have been either dipped into the salt or got
into it accidentally. No question was asked at the trial about such
a likely fact, which would account for one person suffering, and not
another, according as they got the salt or not. The strong taste of
salt would avert suspicion from that of tartar emetic. (_b_) McCleod
said that it was “new cheese—they had it in the house—it was soft—it
tasted hot like pepper.” It is possible, but not easy, by warming and
pounding in a mortar, to mix cheese with a considerable amount of a
powder: it would then look _soft_ and rather unnatural, but might, as
“new cheese,” escape suspicion. This theory is less probable than the
other.
_Tapioca._—Mr. Clark’s remark, p. 438, “Now the suggestion of the
Crown is that the prisoner put antimony in this tapioca, so nicely
adjusted as to produce sickness leading to death, but not so as to
produce death itself,” is inconclusive, as it requires a considerable
amount to produce _death_. A large quantity of tartar emetic could be
mixed with tapioca without suspicion, and would not betray itself by
any peculiar appearance on cooking. The same remark applies to the
sago in Winslow’s case.
_Egg-flip._—“The amount of antimony introduced on the sugar into the
egg-flip must have been a very powerful dose, because Patterson took
only a teaspoonful and lay vomiting and suffering all night.” The total
amount was a tumblerful (= 10 fluid ounces). Mrs. Pritchard took a
wine-glassful (= 2 fluid ounces); was sick very soon and all night.
Mary Patterson took a teaspoonful, was sick immediately, and vomited
frequently throughout the night. Her dose must have been at least 1
grain. This would make 60 grains in the whole. Such a quantity of
tartar emetic would be about a teaspoonful, and obviously could not
be introduced on two lumps of loaf sugar, as the following experiment
shows:—Two rather large pieces of loaf sugar weighing together 204
grains were gently shaken with powdered tartar emetic, and the loose
part shaken off. The lumps now looked rather powdery, but nothing very
noticeable. The amount of tartar emetic they had taken up was nearly
3 grains (2·96), not nearly a teaspoonful, though amply sufficient to
cause vomiting. It is not the _porosity_, but the roughness of surface,
that enables a powder to adhere to the sugar. The tartar emetic might
have been slipped into the egg-flip, out of the hand, at the same time
that the sugar was added, the mixture being afterwards stirred up.
DR. SMETHURST’S CASE.
DR. TAYLOR AND MR. HERAPATH.
In his evidence before the committing magistrates, on the 20th of May,
Dr. Taylor said:—
“I found no arsenic or antimony in any of the bottles delivered to me
by Inspector McIntyre on the 5th and 7th of May, except one, and the
homœopathic medicine: that one was bottle 21.[192] When I received this
bottle it was about half full of thin, watery-looking mixture, and
I tested it. It had a cooling, pleasant saline taste, not repugnant,
no smell. I detected nothing wrong with the taste. I evaporated some
in a glass, and examined it by the microscope, and then found it was
not tartar emetic, as I thought. I then applied the tests for arsenic,
and every test I tried was destroyed, and failed to show the existence
of arsenic, owing, as I supposed, to there being in it, and my tests
convinced me that there was, something very peculiar about it that I
had not met before. I tried Reinsch’s process, but I found that it
dissolved the copper-gauze as soon as I put it into the liquid. I then
determined to extract this noxious agent, and continued to put in
copper-gauze until it no longer possessed the power to dissolve it.
I then put in a piece of copper, which at once received the arsenic.
I was able to decide by these tests that the mixture was chlorate of
potash. I found there was of chlorate of potash 7 grains to the ounce,
or 1 and 6/10ths per cent., and there was a grain of arsenic to every
ounce. I found that the taste of the liquid in this bottle was such
that no one would be likely to suspect that it contained arsenic,
more particularly as the quantity of arsenic was so small that the
liquid could be mixed with any kind of food and swallowed without the
person being aware of it.[193] In the bottles brought to me by Dr.
Berry[194] I found arsenic—_that was white arsenic_. I could not give
an opinion on that in the evacuation (No. 2), as that was mixed with
blood and mucus. In No. 1 there was biliary matter without any metallic
substance.”
Subsequently to the conviction of Smethurst, Mr. Herapath wrote the
letter to the _Times_, on the 27th of August, before referred to in the
Lord Chief Baron’s communication to the Home Secretary, in which, after
a wordy and personal attack on Dr. Taylor, with special reference to
his having used for twenty years untested copper, he said:—
“But was the arsenic said to have been found in bottle 21 really in
the copper used to prove its presence? Could the copper wire-gauze
dissolved by 7 grains of chlorate of potash and its associated
hydrochloric acid deposit one grain of arsenic? In the face of all
England, I say it could not. The 100th part of a grain of arsenic in
that quantity of copper would render it so brittle that it could not
be drawn into wire at all, much less into fine wire fit for gauze. The
fact is the whole set of operations were a bungle. Reinsch’s process
is inapplicable where nitrates or chlorates are present. Taylor must
have known this: it was well known then that chlorates, nitrates,
arsenates, and other oxidizing agents, interfered with Reinsch’s
process. When Taylor found the copper dissolved—he knew that one of
these oxidizing agents was present—he ought then to have either used
Marsh’s test instead of Reinsch’s, or should have prepared the solution
by sulphurous acid first. The method he did use was as dangerous as
could be.”
Whether Mr. Herapath communicated this opinion to the friends of
Smethurst before the trial, as he ought to have done, does not appear.
At any rate he was not called for the defence, and his opinion was
apparently only made public after the conviction. It stands, therefore,
like all the other communications laid before the Home Secretary,
untested by cross-examination. How far was he correct?
Taylor does not state how much of the liquid in bottle 21 he took
for analysis. Assuming that he took 1 ounce, 7 grains of chlorate
would dissolve, _at the most_, 22 grains of copper. If this yielded
1 grain of arsenic, the copper must have contained 4½ per cent. of
that poison—an impossible quantity. Less than ½ per cent. of arsenic
renders copper brittle. So far Herapath was right.[195]
(2.) If Taylor was right that what he got was _white arsenic,
that could not have come from the copper, which can only contain
arsenicum—metallic arsenic_. Therefore if Taylor’s analysis was not
altogether wrong, _in bottle 21 there really was arsenic, and the
prisoner was proved to have had the materials for poisoning in his
possession_.
Taylor’s procedure in dissolving up piece after piece of copper, which
had not been previously proved, by the same process, not to contain
arsenic, was highly blameable, and his assertion that he had previously
tried his tests and found them pure, was not strictly true. Altogether,
his tests both for arsenic and antimony were not reliable.
* * * * *
ADDENDA.
The “bismuth” frequently referred to in the report of Smethurst’s
trial is the Bismuthi Subnitras, B. P., also known by the various
names of “Bismuthum Album,” “White Bismuth,” “Trisnitrate of Bismuth,”
“Subnitrate of Bismuth,” “Magistery of Bismuth,” “Pearl White,” &c.
This compound is a basic nitrate of bismuth, Bi N 0_{4}, H_{2} 0: it is
insoluble in water, and is a heavy, white, minutely-crystalline powder,
much used in medicine, and also as a cosmetic. The name “bismuth” is
misleading as applied to this drug, which is _not_ bismuth, but a
_salt_ of that metal.
Ordinary subnitrate of bismuth frequently contains various
adulterations and impurities. The most usual adulterants are carbonate
of lead, carbonate of lime and phosphate of lime (Royle’s Materia
Medica, 1876): among the impurities which have been found are ammonia
(Piper, Pharm. Journ., Ap. 21, 1877), arsenic, lead, iron, chlorine,
and sodium salts. Some specimens of bismuth subnitrate analysed by
Herapath contained 1 grain of arsenic in 1000: others contained as
much as 1 grain in 433. Taylor, also, found arsenic in three samples
out of five examined by him. Riche (J. Pharm. et Chim., 5, 384)
states that the majority of commercial samples of bismuth subnitrate
contain lead and arsenic, the former to the extent of ·03-·04 per
cent. (as sulphate), and the latter (as arsenious acid) to ·002-·01
per cent., while Chas. Ekin (Pharm Journ., 3, III., 381) remarks that
this preparation of bismuth is often very impure, containing much
subchloride, copper, and occasionally lead. On the other hand, three
specimens of subnitrate of bismuth, analysed by Bernays, contained no
arsenic, lead, or carbonic acid, while the percentage of bismuth oxide
present closely approximated to the theoretical amount. Moreover, in
the Practitioner, Mar. 1871, p. 191, the results of the examination of
six samples of bismuth subnitrate are given, the only impurities found
being traces of chlorine and sulphuric acid: there was no arsenic.
_Hence it is evident that subnitrate of bismuth does not always contain
arsenic: and the quantity of this impurity, when present, is so minute
as (having regard to the small doses in which the drug is usually
prescribed in medicine) to be insufficient to produce the graver
symptoms of arsenical poisoning._[196]
The presence of arsenic in bismuth subnitrate may easily be detected by
Marsh’s test.
Subnitrate of bismuth nearly always contains arsenic and other
impurities, when it has been prepared from commercial bismuth. The
British Pharmacopœia, therefore; very properly directs that _purified_
bismuth (Bismuthum Purificatum, B. P.) should be used in the
preparation of this drug: the B. P. method of purifying the metal is
as follows. 10 ounces of bismuth and 1 ounce of nitrate of potash are
fused together in a crucible, heated and stirred, until the salt has
solidified into a slag over the metal: the salt is now removed, another
ounce of nitrate of potash is added, and the remainder of the process
is repeated. The fused bismuth is now poured into a mould, and allowed
to cool.
Herapath states that the arsenic is not all removed by this process,
and he proposes to boil the nitrate in solution of a caustic alkali,
which removes the arsenic and converts the bismuth into oxide, from
which the salts can be prepared (Royle).
From the purified metal subnitrate of bismuth can be prepared by the
following process, which is that given in the British Pharmacopœia.
2 ounces of purified bismuth are gradually added to a mixture of 4
fluid ounces nitric acid with three ounces distilled water: when
effervescence has ceased, heat is applied for a few minutes, and
the solution is decanted from any insoluble residue. The liquid is
concentrated by evaporation to 2 fluid ounces, and poured into half a
gallon of distilled water. The precipitate formed (Bi N 0_{4}, H_{2}
0) is well washed by decantation, filtered, and finally dried at a
temperature not exceeding 150° F.
In the event of the bismuth used not having been thoroughly purified,
and being therefore still likely to contain a trace of arsenic, a
modification of the above process, recommended by R. Schneider (Journ.
Prakt. Chem., 1879, 418), may be employed. It consists in _heating_
the acid before the bismuth is added, and continuing the heating until
the metal is dissolved. If arsenic be present, the solution will
contain in suspension a white precipitate of _bismuth arsenate_, which
is nearly insoluble in nitric acid, and can be removed by filtration
through asbestos, before the solution is diluted. Cold nitric acid
would convert any arsenic present into _bismuth arsenite_, which is
readily soluble in nitric acid, and could not, therefore, be separated
by filtration.
“_Grey powder_” is Hydrargyrum cum Creta, B. P., and consists of one
part of metallic mercury in a very finely divided state, mixed with
two parts of chalk. It is made by rubbing mercury and prepared chalk
together until metallic globules are no longer visible. The mercury
in this preparation always becomes in course of time more or less
oxidised, the amount of oxide formed varying according to the length of
time the mixture has been kept, and the extent of its exposure to the
air.
Iron, silica, and phosphoric acid, might be present in very small
quantities as impurities, in many samples of grey powder: caustic
lime could not possibly occur, unless the specimen had been subjected
to a red heat, which would drive off the mercury and so spoil the
preparation. Antimony and arsenic would rarely be met with as
impurities in grey powder, and if present, would only be in very minute
quantities.