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to voluntary muscles, prolonging the contraction ; but this effect
is done away with by the application of potassium salts.

THERAPEUTICS OF BARIUM SALTS.

These are not often given, but the chloride (dose, ^ to ^
gr., .006 to .03 gm.) has been used for mitral insufficiency
accompanied by irregularity of the heart, for haemorrhage,
and as a stimulant in atony of the bladder or intestine.
Formerly it was given in nervous diseases.] The waters of
Llangammarch wel)s contain 6.7 gr. [.40 gm.] to the [Imper-
ial] gallon [4545 c.c.] of barium chloride, and have been used
in cardiac cases. [The sulphide (not official) has been used as
a depilatory.

TOXICOLOGY.

Symptoms. Poisonous doses cause salivation, thirst, vomiting, purging,
difficulty of breathing, a slow pulse, and, from its action on the spinal cord,
paralysis of the limbs. The heart is arrested in systole.



1 62 INORGANIC MATERIA MEDICA,

Treatment. Poisoning should be treated by non-irritant emetics and
draughts of weak solution of sodium or magnesium sulphate, followed by
albuminous drinks, and diffusible stimulants. ]

IV. MAGNESIUM.



1. MAGNESII SULPHAS. [Magnesium Sulphate. MgSO 4 +H 2 O
=245.84. Synonym. Epsom Salt.

SOURCE. It is obtained from (l) Dolomite (native Calcium and Magne-
sium Carbonate) ; or (2) Magnesite (native Magnesium Carbonate), by the
action of Sulphuric Acid, (i) MgCO,+MgSO 4 +2H 2 SO 4 =CaSO 4 -|-MgSO 4
+2H 2 O or (2) MgCO g +H 2 SO 4 MgSO 4 +H 2 O-f-CO 2 . Treat with water,
filter and evaporate the filtrate to crystallization.

CHARACTERS. Small,] colorless, rhombic prisms or acicular crystals, very
like Zinc Sulphate, but moister, and of a bitter taste, whilst that of the Zinc
Salt is metallic. Solubility. In 1.5 parts of cold water.

INCOMPATIBLES. Alkaline carbonates, phosphoric acid, phosphates, lime
water, lead acetate and silver nitrate.

IMPURITIES. Lime and Iron.

[Magnesium Sulphate is contained in Infusum Sennae Compositum.]

Dose, % to i oz. ; 8. to 30. gm.

2. MAGNESII CARBONAS. [Magnesium Carbonate. (MgCO s ) 4 ,

Mg(OH) 2 +5 H 2 0=48 4 .62.

SOURCE. Mix strong, boiling aqueous solutions of Magnesium Sulphate
and Sodium Carbonate, and evaporate. 4MgSO 4 -f4Na 2 CO 3 -f-H 2 O:=(Mg
CO S ) 4 , Mg(OH) 2 4-4NajSO 4 +CO 2 . Digest with water, filter and dry.

CHARACTERS. Light, white friable masses, or a light white powder,
without odor, and having a slightly earthy taste. Solubility. Almost insolu-
ble in water.

IMPURITIES. Lime and sulphates.

Magnesium Carbonate is used to prepare Magnesia.

Dose, ]^ to 2 dr. ; i. to 8. gm.]

Preparations.

i. Magnesii Citras Effervescens. [Effervescent Magnesium
Citrate. Magnesium Carbonate, 10 ; Citric Acid, 46 ; Sodium Bicar-
bonate, 34; Sugar, 8 ; Alcohol and distilled water, a sufficient quantity.

CHARACTERS. A white, coarsely granular salt, without odor, and
having a mildly acidulous, refreshing taste, deliquescent. Solubility.
With copious effervescence, in 2 parts of water ; almost insoluble in
Alcohol.

Dose, ' 4 to i oz. ; 8. to 30. gm.



METALS OF THE ALKALINE EARTHS MAGNESIA. 163

2. Liquor Magnesii Citratis. Solution of Magnesium Citrate.
Dissolve Magnesium Carbonate, 15 ; in a solution of Citric Acid, 30;
add Syrup of Citric Acid, 60 ; then crystals of Potassium Bicarbonate,
25. Cork and wire immediately. It effervesces when uncorked.

Dose, 2 to 8 fl. oz. ; 60. to 240. c.c.]

3. MAGNESIA. Light Magnesia. MgO [=40.26.] Synonym. Cal-
cined Magnesia.

SOURCE. [By heating the official Magnesium Carbonate ; water and Car-
bon Dioxide are given off, and Magnesium Oxide remains behind. 4(MgCO 3 ),
Mg(OH ) 2 + 5 H 2 0= 5 MgO-f 4 C0 2 -f6H 2 0.

CHARACTERS. A white, very light and very fine powder, without odor,
and having an earthy, but not saline taste. Solubility. Almost insoluble in
water ; insoluble in Alcohol.

Light Magnesia is used to prepare Heavy Magnesia and is contained in
Massa Capaibae, Pulvis Rhei Compositus and Ferri Oxidum Hydratum cum
Magnesia.

Dose, 5 to 60 gr. ; .30 to 4.00 gm.]

4. MAGNESIA PONDEROSA. Heavy Magnesia. [MgO=4O.26.
SOURCE. From Magnesia by trituration for some time in the presence of

strong Alcohol, drying, and rubbing to powder.

CHARACTERS. A white, dense and very fine powder, which should cor-
respond to the tests for Magnesia, from which it differs in not readily uniting
with water to form a gelatinous hydrate. ]

Dose, 5 to 60 gr. ; [.30 to 4.00 gm.]

ACTION OF MAGNESIUM SALTS.

External. None.

Internal. Stomach and Intestines. Magnesia and magne-
sium carbonate are antacid, acting in many ways like the potas-
sium and sodium alkalies. Carbon [dioxide] is given off, if the
carbonate has been given, and is sedative to the stomach. They
are both decomposed by the gastric juice, magnesium chloride,
lactate and bicarbonate being formed. These salts, or the sul-
phate, if that has been taken, act in the intestine, as typical
saline purgatives. The sulphate is most powerful. The
mode of action of this group of purgatives has been discussed
on p. 93.

Blood and Urine. Like other alkaline remedies, these mag-
nesium salts increase the alkalinity of the blood, alkalize the
urine, help to keep uric acid in solution, and are diuretic. But



164 INORGANIC MATERIA MEDICA.

their action on the blood and urine is feebler than that of potas-
sium and sodium salts, for they are with difficulty absorbed.
Large doses injected into the blood of animals are toxic, killing
by their action on the heart.

THERAPEUTICS OF MAGNESIUM SALTS.

Internal. 'Stomach. Magnesia and the carbonate are mild
alkaline remedies, and may be used in the same class of cases as
other alkalies. They form insoluble compounds with mineral
acids, oxalic acid, and mercury, arsenic and copper salts. By
alkalizing the gastric contents they hinder the absorption of
alkaloids. They are, therefore, antidotes to all these substances ;
the objection to them is their bulk. Magnesia is to be preferred,
as the carbonate gives off carbon [dioxide] gas. They must be
freely given. The sulphate is an antidote to lead and barium
salts, forming insoluble sulphates.

Intestines. The magnesium salts are very common purga-
tives. Magnesia, the carbonate, and the citrate are excellent
for children. The sulphate is one of our best saline purgatives.
It is very largely used, especially for the varieties of constipation
that are associated with hepatic disorder, gout or excessive uric
acid. Its use is then spread over some time, and it may conve-
niently be taken as one of the mineral waters which contain it
and sodium sulphate {see p. 144). A concentrated solution,
causing as it does an increased secretion of intestinal fluid, is a
useful purge for dropsy or ascites. [It is useful with glycerin in
concentrated enema for thorough cleansing of the bowels before
surgical operations (glycerin, i oz. ; 30. c.c., in a saturated
solution of magnesium sulphate, in hot water 3 oz. ; 90. c.c.,
which is allowed to cool). It can also be used hypodermatically
in dose of 3 gr. ; .20 gm., which frequently will cause a watery
evacuation. In operations during which the abdomen is opened,
the subsequent intestinal paralysis can be prevented from causing
constipation by injecting into the small intestine through a cannula
one ounce; 30. c.c. of a saturated solution of magnesium sul-
phate. The wound in the bowel should be closed by a Lembert
stitch.]



THE SALTS OF LEAD. 165

Blood and kidneys. So little of these salts is absorbed that
they are only to be given for their alkaline effects on the blood
and urine in those cases of gout and uric acid gravel in which
potassium or sodium salts cannot be borne.

V. CERIUM.
6=139.9.

CERII OXALAS. [Cerium Oxalate. Ce.j(C 2 O 4 ) 3 +9 ^0=704.78.
Synonym. Cerous Oxalate.

SOURCE. The powdered mineral is heated with concentrated Sulphuric
Acid, ignited, then dissolved in dilute Nitric Acid and treated with Hydrogen
Sulphide to remove copper; the calcium salt is held in solution by a little Hy-
drochloric Acid, and the ce'rite metals are precipitated as oxalates by Oxalic
Acid. It is purified by calcination and solution, reduced to a cerous salt and
precipitated by Oxalic Acid.

CHARACTERS. A white granular powder, without odor or taste. Solu-
bility. Insoluble in water, Alcohol or Ether.]

IMPURITIES. Aluminum and lanthanum and didymium oxalates.

Dose, i to 8 gr. ; [.06 to .50 gm.]

THERAPEUTICS OF CERIUM OXALATE.

It is given empirically for vomiting, especially for that of
pregnancy, and occasionally with benefit. No physiological
action is known. [The dose above given is often exceeded ; 30
gr. (2. gm.) ; have been frequently given with good results,]

GROUP IV.

Plumbum, Argentum, Zincum, Cuprum, Bismuthum,
Aluminum.

The pharmacopceial Salts of these metals are powerful astringents.
Many of them have some Salts which are emetic, and others which, when
applied locally, are Caustic. Aluminum pharmacologically falls into this
group.

I. PLUMBUM.

Pb=2o6.4.

i. PLUMBI OXIDUM. [Lead Oxide. PbO=222.36.] Synonym.
Litharge.

SOURCE. Made by roasting Lead in air.



1 66 INORGANIC MATERIA MEDICA.

CHARACTERS. [A heavy, yellowish or reddish-yellow powder or minute
scales, without odor or taste. Solubility. Almost insoluble in water ; soluble
in Nitric and Acetic Acids.

IMPURITIES. Copper, iron and carbonates.

Lead Oxide is used to make Liquor Plumbi Subacetatis. ]

Preparations.

1. Emplastrum Plumbi. Lead Plaster. This is LEAD OLEATE,
and is sometimes called Diachylon Plaster. [Lead Oxide, 3200,
is boiled in water, and Olive Oil, 6000. When the mass has acquired
a whitish color and is perfectly homogeneous, it is well kneaded to
remove the Glycerin and divided into rolls of suitable size. ] 3 PbO-f-
3H 2 0-f2(C 3 H 6 (C 18 H 33 2 ) 3 )=3(Pb 2 (C 1 8H 33 2 ) 2 )+2(C 3 H.(OH) 3 ).

[Lead Oxide or its Plaster is contained in Emplastrum Ammoniac!
cum Hydrargyro, Ferri, Hydrargyri, Opii, Resinse, and Saponis.

2. Unguentum Diachylon. Diachylon Ointment. Lead Plas-
ter, 500; Olive Oil, 490 ; Oil of Lavender Flowers, lo. ]

2. PLUMBI ACETAS. Lead Acetate. Pb(C 2 H 3 O. ! ) 2 -f 3H 2 O[=
378.0.] Synonym. Sugar of Lead.

SOURCE. [Metallic Lead is dissolved, in the presence of air, in Acetic
Acid. PbO+2C 2 H 4 O 2 4-2H 2 O=Pb(C 2 H 3 O 2 ) 2 +3H 2 O. To obtain well-de-
fined crystals 'the solution must have a distinctly acid reaction.

CHARACTERS. Colorless, shining, transparent, monoclinic prisms or
plates, or heavy, white, crystalline masses, or granular crystals, having a faintly
acetous odor, and a sweetish, astringent, afterwards metallic taste. Efflores-
cent, and absorbing Carbon Dioxide, on exposure to the air. Solubility. In
1.8 parts of water.]

INCOMPATIBLES. Hard water, mineral acids and salts, alkalies, lime
water, potassium iodide, vegetable astringents, preparations of opium, and
albuminous liquids.

IMPURITY. Lead carbonate.

Dose, y z to 5 gr. ; [.03 to .30 gm.]

Preparations made from the Acetate in which Lead exists as the SUBACE-
TATE, Pb 2 0(C 2 H 3 2 ) 2 =5 4 6. 4 8.

[i. Liquor Plumbi Subacetatis. Solution of Lead Subacetate.
Synonym. Goulard's Extract. Lead Acetate, 170 ; and Lead Oxide,
loo ; are boiled together in distilled water, to make 1000. An aqueous
liquid containing approximately 25 per cent, of Lead Subacetate.

2. Liquor Plumbi Subacetatis Dilutus. Diluted Solution of
Lead Subacetate. Synonym. Lead Water. Liquor Plumbi Subaceta-
tis \ 30 ; distilled water to 1000.

3. Ceratum Plumbi Subacetatis. Cerate of Lead Subacetate.



THE SALTS OF LEAD. l6/

Synonym. Goulard's Cerate. Solution of Lead Subacetate, 200;
Camphor Cerate, 800.]

3. PLUMBI CARBONAS. [Lead Carbonate. A mixture of Car-
bonate and Hydrate. (PbCO 3 ),Pb(OH } 2 =772.82. Synonym. White Lead.

SOURCE. Expose Lead to the vapor of Acetic Acid and to air charged
with Carbon Dioxide. 6Pb+6HC 2 HjOj-f30 2 -f2CO 2 =(PbCO 3 ), Pb(OH),-f
2H 2 O+2Pb(C 2 H 3 O 2 ) 2 .

CHARACTERS. A heavy, white, opaque powder, or a pulverulent mass,
without odor or taste.

IMPURITY. Lime.

Preparation.

Unguentum Plumbi Carbonatis. Ointment of Lead Carbon-
ate. Lead Carbonate, 10 ; Benzoinated Lard, 90.]

4. PLUMBI NITRAS. -[Lead Nitrate. Pb(NO 3 ) 2 =33O.i8.
SOURCE. Dissolve Lead in warm diluted] Nitric Acid.
CHARACTERS. [Colorless, transparent, octahedral crystals, or white

opaque crystals ; without odor, and having a sweetish, astringent, afterwards
metallic taste.

Ledoyen's Disinfecting Fluid is Lead Nitrate, I ; dissolved in water, 8
parts.]

5. PLUMBI IODIDUM. [Lead Iodide. PbI 2 =43O.46.

SOURCE. Mix solutions of Lead Nitrate and Potassium Iodide and dry
the precipitate. Pb(NO 3 ) 2 +2KI=2KNO 3 -f-PbI 2 .

CHARACTERS. A heavy, bright-yellow powder, without odor or taste.
Solubility. In about 2000 parts of water.

Preparation.

Unguentum Plumbi lodidi. Ointment of Lead Iodide. Lead
Iodide, 10 ; Benzoinated Lard, 90.]

ACTION OF LEAD SALTS.

External. The action of lead salts on the unbroken skin,
if they have any, is very slight ; but when applied to the abraded
skin, to sores and to ulcers, they coagulate the albumin of the
discharge, thus forming a protective coat ; they coagulate the
albumin in the tissues themselves ; and they contract the small
vessels ; for these three reasons they are powerfully astrin-
gent. They also soothe pain, and are therefore excellent local
sedatives. It is obvious that substances so markedly astringent



1 68 INORGANIC MATERIA MEDICA.

will be haemostatics. Any salt may be irritant and caustic if
enough be used, and it is sufficiently concentrated.

Internal. Lead salts act on mucous membranes precisely
as on the unbroken skin, and are therefore powerfully astringent
and haemostatic to all parts of the alimentary canal, from the
mouth downwards. In the stomach they are converted into a
chloride. (For other actions see Toxicology.)

THERAPEUTICS OF LEAD SALTS.

External. Lead salts are applied as lotions or ointments in
many conditions for which an astringent, sedative effect is de-
sired, as in weeping eczema and many varieties of ulceration.
The glycerin of the subacetate [B. P., lead acetate, 10 ; lead
oxide, 7 ; glycerin, 40 ; water, 24 ; boiled together] diluted
fourfold with glycerin or milk is useful for these conditions.
The lotions may be injected in vulvitis, leucorrhoea, gleet and
otorrhoea, but should not be applied for ulceration of the cornea,
lest the white precipitate formed should lead to permanent
opacity. The sedative effect is well seen in their use in pruritus ;
but of course the cause of the itching should, if possible, be re-
moved. The Liquor Plumbi Subacetatis is rarely used, as it is
strong enough to irritate ; the diluted form is that usually em-
ployed when a lotion is desired. It is often applied to bruises
when the skin is unbroken, but is doubtful if it is absorbed.
The ointment is an excellent remedy, and a lotion of lead and
opium is a favorite preparation. It may be made by mixing 5 gr.
[.30 gm.] of extract of opium with i oz. [30. c.c.] of Liquor
Plumbi Subacetatis Dilutus and i oz. [30. c.c.] of water. Di-
achylon ointment mixed with an equal quantity of zinc oleate
and mercuric oleate ointments forms a transparent ointment ex-
cellent for many purposes.

Internal. The chief uses of lead salts (the acetate is the
only one given internally) are as astringents in severe diarrhoea,
such as that of typhoid fever, and as haemostatics, as in gastric
ulcer, or in haemorrhage from the intestine, especially if severe,
as in typhoid fever or tuberculosis. For these purposes the
Pilula Plumbi cum Opio [B. P., lead acetate, 3 gr.; .20 gm.;



THE SALTS OF LEAD. 169

opium, i gr. ; .06 gm.] is very valuable, and suppositories con-
taining the same amount of the ingredients may be employed for
rectal haemorrhage. Lead salts produce marked constipation.
Other preparations are generally preferred, but lead subacetate
may be used as a gargle when an astringent effect on the mouth
or pharynx is desired.

TOXICOLOGY.

ACUTE LEAD POISONING. As when applied externally, so when taken in-
ternally, the lead salts, if concentrated, are powerful irritants. Cases of acute
poisoning are rare. The Acetate is most frequently taken. There is a burn-
ing, sweetish taste in the mouth, thirst, vomiting [of whitish fluid due to lead
chloride], abdominal colic, and usually constipation, but if the bowels are
open the faeces are black [due to lead sulphide] : the skin is cold, and there is
collapse. If the patient live long enough, cramps in the legs, giddiness, torpor,
coma, and convulsions are present. Post-mortem. The stomach and intes-
tines show signs of irritant poisoning.

Treatment. Give emetics (see p. 139), or wash out the stomach. Give
Sodium or Magnesium Sulphate to form an insoluble sulphate, and to open
the bowels. If collapse is present, stimulants and warmth should be used.

CHRONIC LEAD POISONING. This is so common [that the sources of acci-
dental poisoning should be borne in mind. The most important are : soft
water, carbonated waters and alcoholic drinks (beer) which have passed
through lead pipes or been stored in receptacles lined with lead. Occupations
as painters (colica pictonum), plumbers, type-setters, gold-miners, white lead
workers, potters, glaziers (Devonshire colic) because] they will not wash their
hands before meals [nor use ordinary care ; lead hair dyes and face powders,
biting leaded white thread, eating certain canned fruits (lead solder), sheet-
lead (tin-foil) about tobacco, filling holes in mill-stones with lead, giving of tin
(lead) soldiers to children, use of lead carbonate ointment on burns, lead
bullets in flesh, white or red lead used for preparing rubber for Vulcanizing,
lead plates in dentistry (Osier), the use of lead chromate to color buns yellow-
ish, have all been followed by chronic plumbism.]

Symptoms. The earliest are constipation and intestinal colic. Lead is
certainly absorbed, for it circulates in the blood and is excreted, chiefly, by
the kidneys. It is supposed to be taken up as an albuminate, but it cannot
exist in the blood as such, for it would be precipitated by the alkali of that
fluid. After absorption it diminishes the amount of haemoglobin and the num-
ber of red blood -corpuscles, and produces a sallow anaemia ; it checks the
separation of urates from the blood and their excretion by the kidneys, hence
gout is very common in those poisoned by lead. As it circulates in the gums,
and the lead-impregnated plasma bathes the epithelium, through which some
of the sulphur in the food and in the tartar of the teeth has diffused, a Lead
Sulphide is precipitated in the gums, and forms the well-known very dark-blue



I/O INORGANIC MATERIA MEDICA.

line [known as Burton's line], at the base of the teeth. For the same reason
a blue line may occasionally be seen round the anus, and, after death, deposits
of pigment in the intestines. Circulating in the nervous system, lead very often
produces chronic inflammation of the peripheral nerves, especially those sup-
plying the extensors of the hand, and hence wrist-drop is a very common
symptom ; but any muscle, and sometimes almost all the muscles of the body,
may be paralyzed from neuritis [it is a clinical observation that such muscles
are very refractory to electricity]. It is noteworthy that the supinator longus
usually escapes, [the reason apparently being that the supinator is not an ex-
tensor muscle] . The sensory fibres of the nerves are not often affected, hence
pain and anaesthesia are rare ; but pains, especially round the joints, may occur.
In exceptional cases the anterior cornua of the spinal cord wasle, and lead
often affects the brain, causing saturnine lunacy, and also convulsions, known
as saturnine epilepsy. Inflammation of the optic nerve or optic neuritis, some-
times occurs, leading to blindness, which, however, may be present without
any change in the nerve. The kidneys are often the seat of chronic inflam-
mation ; whether this is due to the passage of the lead through them, or to the
gout caused by the lead, is an open question.

Treatment. The treatment consists chiefly in avoidance of the source of
poisoning, [the use of Sulphuric Acid lemonade, and in the administration of
Potassium Iodide which] is often given, as it is supposed to increase the ex-
cretion of lead in the urine. This is probably incorrect as very little lead
passes out by the urine ; most leaves the body by the faeces. It is said also to
be excreted in the bile, sweat, and milk. For a clinical account of the symp-
toms and treatment a text-book of medicine must be consulted.

[The following method may be employed to determine the presence of lead
in the urine. Administer potassium iodide for four days, collecting the urine.
Evaporate to a pint; 500 c.c. , and filter. Pass hydrogen sulphide gas
through the urine thus concentrated, when a black precipitate will form if lead
is present. Other substances give a black precipitate with hydrogen sulphide,
but none are likely to be present in the urine. A simple test is to paint a
small area of skin with a six per cent, solution of sodium sulphite. If lead is
present the painted area will darken after a few days, (Cicconardi). Patients
using face enamels containing lead will find the skin blackened on taking
baths in water containing hydrogen sulphide (Richfield Springs).]

II. ARGENTUM.

Ag.=[u>7.66.

i. ARGENTI NITR AS. Silver Nitrate. AgNO,=l69.55.] Syn-
onym. Lunar caustic.

SOURCE. Dissolve Silver in Nitric Acid with the aid of heat. Evaporate
and crystallize. [6HNO,+3Ag,=6AgNO 3 +3H r

CHARACTERS. Colorless, transparent, tabular, rhombic crystals, becom-
ing gray or grayish-black on exposure to light in the presence of organic



THE SALTS OF SILVER. I /I

matter ; without odor, but having a bitter, caustic and strongly metallic taste.
Solubility. In 0.6 part of water ; and in 26 parts of Alcohol.] It should be
kept in the dark, as light blackens it.

INCOMPATIBLE. Alkalies and their carbonates, chlorides, acids (except
nitric and acetic), potassium iodide, solutions of arsenic and astringent infu-
sions.

IMPURITIES. Other nitrates.

Dose, ^ to i gr. ; [.015 to .06 gm.] in a pill.

Preparations.

[i. Argenti Nitras Dilutus. Diluted Nitrate of Silver. Syn-
onym. Mitigated caustic.

SOURCE. It is a mixture made by fusing together Silver Nitrate,
30, and Potassium Nitrate, 60. The product is poured into moulds.

CHARACTERS. A white, hard solid, generally in the form of pencils
or cones of a finely granular fracture, becoming gray or grayish-black
on exposure to light in the presence of organic matter ; odorless, hav-
ing a caustic, metallic taste, and neutral to litmus paper.

2. Argenti Nitras Fusus. Moulded Nitrate of Silver. Syn-
onyms. Lunar caustic. Lapis infernalis.

SOURCE. By melting Silver Nitrate, IOO ; Hydrochloric Acid, 4 ;
cooling in moulds.

CHARACTERS. A white, hard solid, generally in the form of pen-
cils of a fibrous fracture, becoming gray or grayish-black on exposure
to light.]

2. ARGENTI OXIDUM. [Silver Oxide. Ag 2 O=23i.28.
SOURCE. Shake a solution of Silver Nitrate with a solution of Potassa and

wash the precipitate. 2AgNO 3 4-2KOH=Ag 2 O+KNO s +H 2 O.

CHARACTERS. A heavy, dark brownish-black powder, having a metallic
taste. Solubility. Slightly in water.]

INCOMPATIBLES. Chlorides and organic substances, especially creosote,
for it rapidly oxidizes them and forms explosive compounds.

IMPURITY. Metallic silver.

Dose, y 2 to 2 gr. ; [.03 to .12 gm.] in a pill with kaolin.

3. [ARGENTI CYANIDUM. Silver Cyanide. AgCN=l33.64.
SOURCE. From Potassium Cyanide, which reacts with Silver Nitrate,

producing the precipitate of Silver Cyanide. KCN-f AgNO 3 =AgCN+KNO 3 .

CHARACTERS. A white powder, odorless and tasteless, permanent in dry
air, but gradually turning brown on exposure to light. Solubility. Insoluble
in water and Alcohol.

Silver Cyanide is used to prepare extemporaneously Acidum Hydrocyani-
cuin Dilutum.



INORGANIC MATERIA MEDICA.

4. ARGENTI IODIDUM. Silver Iodide. Agl=234.i9.

SOURCE. From Silver Nitrate and Potassium Iodide, washing and drying
the precipitate. AgNO 3 +Kl=AgI+KNO 3 .

CHARACTERS. A heavy, amorphous, light-yellowish powder, without
odor and taste. Solubility. Insoluble in water and Alcohol.

Dose, ^ to i gr. ; .015 to .06 gm.]

ACTION OF SILVER SALTS.

External. The action of silver salts is very like that of lead
salts, but they are more powerful. Therefore silver nitrate is
much used as a caustic, but it does not act deeply ; it is conse-
quently an admirable agent when we wish a limited caustic action



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