Their action is more readily understood, because it can actually be

seen. It takes place out of the body, or in the body--externally, or

internally. Nearly all astringents have the power of coagulating or

precipitating albumen. By virtue of this power they are enabled to

constrict many dead animal matters. They affect fibrinous tissues in a

similar chemical way. But they seem to possess a further dynamical

influence over living tissues, which possibly depends in some way on

this chemical property. This dynamical influence is, as I have said, to

cause the contraction of muscular fibre. By this all their operations

can be explained. Taken into the blood in a state of solution, they pass

through the walls of the capillaries to the muscular tissue. By inducing

the fibre of the voluntary muscles to contract, Astringents may brace

the system, and simulate the action of Tonics. But as the contraction of

voluntary muscle is short and brief, it requires for its maintenance a

continual excitation, and unless the medicine is thus continually

repeated, the tonic effect subsides. But astringents further contract

involuntary muscle. This contraction is slower, and more durable and

important in its results. Unstriped muscular fibres exist in the middle

coat of arteries, in the walls of capillary vessels, in the lining of

the ducts of glands generally, and in the substance of the heart and the

coats of the stomach and intestines. Astringents are irritant and

poisonous in large doses. But in small doses they constrict and

stimulate to a healthy condition these tubes that contain in their coats

the unstriped fibre. By diminishing the caliber of the capillary vessels

generally, they promote health, and counteract a lax state of the

system. By the same action on the extreme vessels, they prevent

hæmorrhages. By constricting the ducts of the glands they diminish the

secretion of those glands, because denying it an exit. By acting on the

stomach and intestines, they are able to give them tone, to diminish

their secretions when excessive, and thus to promote digestion.

Having premised this general view of their action, we may now proceed to

prove the Proposition in which it is stated, dividing it first into four

minor propositions.

_m. p. 1._--That they are medicines which pass into the blood.

_m. p. 2._--That they have the power of causing the contraction

of muscular fibre, living or dead.

_m. p. 3._--That their operation is to diminish secretion, to

repress hæmorrhage, and to give tone to the

muscular system.

_m. p. 4._--That these results are to be accounted for by their

action on muscular fibre, to which they pass from

the blood.

These assertions are an extension of the major proposition, but their

establishment is necessary to a correct understanding of the latter.

Their proof is comparatively easy and simple. It is not supposed to be a

certainty; but simply to amount to a strong probability, which is as

much as we have a right to expect in such cases.

Astringents constitute the third class of medicines which operate on the

system after being introduced into the stomach. Their action is,

however, of so simple a kind, that it may be exerted on the external

surface in the same way as in the interior of the body. It will be seen

by a reference to the table of medicines, that the class of Astringents

is there divided into two orders.

ASTRINGENTIA.

Ord. 1. Astringentia Mineralia.

Ord. 2. Astringentia Vegetabilia.

The lists of these orders are given below. With regard to the first

minor proposition, it has already been proved that most of these

medicines pass into the blood. The minerals included in the first order

have already been noticed as Hæmatic medicines. They are all soluble in

water. They are absorbed in the stomach and intestines, and pass into

the blood. Many of them pass on into the secretions. The astringent

parts of the vegetables of the second order are also soluble. Tannic

acid is the chief of them; it is simply an Astringent; it has been found

in the blood, where it changes into Gallic acid, and in that form it

passes into the secretion of urine.

What then are the active properties of these medicines? They have all a

certain chemical power; and a certain dynamical power. All the mineral

Astringents have the power of precipitating an albuminous solution. So

also do Tannic acid, Turpentine, and Creosote, coagulate albumen. Tannic

acid precipitates Gelatine too. The dynamical property, which is common

to all of these substances, is a power of causing the contraction of

muscular fibre. It seems to depend somehow on the chemical power just

mentioned; for Astringents appear to constringe fibrinous as well as

albuminous tissues by a chemical action. They also coagulate fluids and

discharges which contain albumen.

When the solution of any Astringent is applied to a fresh fibre of dead

muscle placed under the microscope, it is seen to contract. The power

which they possess in causing the contraction of living blood-vessels

may be witnessed in a similar way. The astringent solution may be

applied to the web of a frog's foot, confined in an extended position.

This web is traversed in all directions by minute ramifying capillaries;

and these are found gradually to diminish in caliber. In the same way as

the mechanical irritation of a small artery will act upon the unstriped

muscular fibre contained in its coat, and thus cause the vessel to

contract at one point; so it seems that an Astringent, by a chemical

action on the same muscular tissue, is able to cause the capillary

vessels seen under the microscope to contract and diminish in size. At

all events we may conclude, both from actual experiment and from a

comparison of their several operations, that Astringents are able to

cause the contraction of muscular fibre.

In the third minor proposition the chief results of their operation are

stated. These have already been briefly described.

They check secretion. They are thus prescribed when any secretion is

excessive. The Tannic vegetables are given in diarrh[oe]a; Nitrate of

Bismuth is administered in Pyrosis; Sulphuric acid in profuse

perspirations; Uvæ Ursi in mucous flux from the bladder.

They repress hæmorrhage. Thus Acetate of lead is employed in

hæmoptysis; Creosote and Uvæ Ursi are used in hæmorrhage from the

stomach or bladder; and the vegetable Astringents are prescribed in

Dysentery.

They give tone to the system. They do this when there exists an

over-relaxation of the solid fibres on account of any depressing cause,

by exciting the muscles to a more or less permanent contraction, and by

constringing the capillary vessels generally.

In the fourth place, it is maintained that their action in all these

instances may be explained by a reference to their power in causing the

contraction of muscular fibre; inasmuch as they are found to diminish

the caliber of certain tubes and cavities, and these owe the

contractility which they possess to the muscular fibre which is

contained in their coats. It follows then from the rule of local access,

that before they can influence these tissues they must pass directly to

them from the blood.

Such appears to be the simplest and the most rational explanation of the

action of Astringent medicines.

ORD. I. MINERAL ASTRINGENTS.

(Sulphuric, Nitric, and Hydrochloric acids. Acetate and Diacetate of

Lead; Sulphate and Sesquichloride of Iron; Alum; Sulphate of Zinc;

Sulphate of Copper; Bichloride of Mercury; Nitrate of Silver.)

These medicines have already been noticed among Restorative and

Catalytic Hæmatics. Their Astringent action on muscle is of much less

moment than their important operations in the blood. Neither is it

theoretically a matter of so much difficulty; for it appears, as we have

seen, to admit of a simple explanation.

By their chemical action on albumen, these substances coagulate blood,

and thus act in a simple way as styptics when applied to bleeding parts

externally. They form peculiar insoluble compounds both with albumen and

fibrine, and it is probably by virtue of their action on the latter

that they are able to cause the contraction of muscular fibre, which is

a fibrinous tissue. The constriction, set up chemically, is apparently

continued and propagated by the vital force of the muscle.

The most important only of the mineral Astringents are mentioned above.

It must not be supposed, when their chemical actions are mentioned, that

such actions are always allowed free play in the living and circulating

blood. They are no doubt constrained by various forces from operating

there, or else the consequences of such a disturbance of the condition

of the elements of the blood would be dangerous in the extreme. (_Vide_

page 104.) They act, before entry into the blood, on mucous membranes

and external parts; and on coming out of the blood, on the terminal

capillary vessels, on the ducts of glands, and on mucous membranes

again.

Astringents act very much alike on external parts; only that some are

more soluble than others, and some excel the rest in chemical activity.

But they differ considerably in their applicability for internal use.

They must be given in such quantity that, after absorption and dilution

by the whole mass of the blood, they may still be capable of exerting a

perceptible action on distant parts. A small portion of one of them will

not suffice to repress hæmorrhage, or to diminish a super-abundant

secretion.

From this it follows that the mineral acids, Alum, and the salts of

Iron, are the only astringents of this order which can in all cases be

given internally with advantage. For being comparatively innocuous, they

can be safely prescribed in the quantity required; whereas the other

mineral Astringents are poisonous substances, which cannot be given in

large doses without considerable danger.

Of the mineral acids, Sulphuric acid is the best Astringent. Phosphoric

acid is seldom or never used as an Astringent. We might indeed have

supposed it to be inapplicable, from the fact that it forms soluble

compounds with albumen and fibrine,--instead of coagulating these

substances, like the other mineral acids.

Sulphuric acid is a Restorative Hæmatic; and, when given in small doses,

may remain in the blood, and not pass out through the glands. It acts

first upon the mucous surface of the stomach. When there is a relaxation

of this mucous membrane, as in many cases of atonic dyspepsia, with a

large formation of flatus, and an over-secretion of the gastric fluid,

this acid may be very serviceable. It tends to correct these evils by a

topical action. In cases of Pyrosis, where there is an alkaline reaction

in the vomited fluid, as sometimes occurs, Sulphuric acid is still more

peculiarly applicable, because it further acts chemically in

neutralizing this alkali. When given in large doses, the acid cannot

remain in the system, but must be excreted from it by the glands. In

passing through them it tends to act as an Astringent by corrugating and

diminishing in caliber their minute ducts, and thus decreases the amount

of the secretion. But it does not act on all glands alike. Dr. Bence

Jones has found that it seldom passes out into the urine. It therefore

does not sensibly diminish the secretion of urine. It is probably

excreted partly by the skin, and partly by the bowels; for it diminishes

the amount of the sweat in profuse perspiration, and of the fæces in

diarrh[oe]a. Sulphuric acid is free before entrance into the blood, and

after expulsion from it into the secretions. Thus at these periods it

acts as an Astringent. But while in the blood it combines with the

alkali contained in that fluid, and forms a salt which is not

astringent. So that when it diminishes any secretion, this is nearly

tantamount to a proof that it is actually excreted by the gland which

forms that secretion. It acts on mucous membranes generally, being

probably excreted in small quantities by those which are remote from the

stomach. It is not of use in cases of hæmorrhage, except when the

bleeding takes place from some mucous membrane. It is thus given with

more or less advantage in Hæmatemesis, Hæmoptysis, Melæna, and chronic

Dysentery--_i.e._ in hæmorrhage from the mucous surfaces of the lungs,

stomach, and bowels.

Alum is a universal Astringent, acting more or less on all parts of the

body, and diminishing all secretions. It is a very useful remedy in all

cases where Astringents are required. It does not seem to be impaired in

power while in the blood, as is the case with Sulphuric acid; and is

therefore applicable in all hæmorrhagic cases. It has been highly

recommended in the case of lead colic, and seems to operate in this

instance by stimulating to contraction the muscular fibre of a paralyzed

portion of the intestine.

The astringent salts of Iron are less active in this kind of influence

than the medicines already referred to. They have very little action on

the glands. But in cases of hæmorrhage they are particularly

appropriate, for in addition to their astringent action they tend to

restore the deficient red colouring matter of the blood. In many such

instances the Sulphate or the Sesquichloride of Iron may be

advantageously prescribed along with Sulphuric acid.

Acetate of Lead is used internally as an Astringent, but being a more

dangerous remedy than the medicines above mentioned, it requires greater

care in its application. It should not, if possible, be used long at a

time. When it has been for some time prescribed, the blue line at the

edge of the gums, which is characteristic of a saturation of the system

by the poison of lead, will indicate that its further administration is

unadvisable. The Acetate of Lead is much esteemed as an Astringent in

the case of Hæmoptysis. It is frequently combined with Opium, in spite

of the chemical decomposition which follows the admixture. But it must

certainly not be prescribed with Alum.

The soluble salts of Silver, Zinc, and Copper, and the Bichloride of

Mercury, are used with advantage as external Astringents, but can seldom

be prescribed internally so as to act in this way, because they are

poisonous when given in any quantity. The Sulphates of Zinc and Copper

have, however, been occasionally used in diarrh[oe]a.

When thus applied as Astringents externally, their solutions must be

very dilute, for all the mineral Astringents are caustic and corrosive,

destroying texture, when in the solid state, or in strong solutions.

These solutions may be applied to any part of the surface of the skin or

mucous membrane, when relaxed, inflamed, or ulcerated. Their operation

is simple and obvious. When one of them is applied to an inflamed eye,

or to a red ulcerated sore, that is turgid with blood and discharges an

unhealthy matter, it tends to promote the contraction of the dilated

vessels, and thus dispels the congestion and diminishes the discharge.

Various other substances have wrongly obtained the title of Astringents,

regard being had only to the result of their operation, and not to the

mode in which it is produced. Thus Chalk is often of benefit in

diarrh[oe]a. It acts both by mechanically absorbing irritating fluids,

and protecting the surface of the bowel, and by chemically neutralizing

an acid matter by which the irritation is maintained. And when applied

to the surface of inflamed ulcerated parts, it does good by absorbing

the discharge, and protecting from the contact of air. Thus its action

in both cases is very different from that of the true Astringents.

The action of some of the minerals above named, when applied externally

in the solid state, as caustics, must not be confounded with their

astringent power. Its efficacy depends upon the revulsive effect which

follows a local destruction of tissue.

ORD. II. VEGETABLE ASTRINGENTS.

(Tannic Acid. Gallic Acid. Kino; Catechu; Logwood; Oak-galls; Rhatany;

Bistort; Pomegranate-rind; Rose-leaves; Uvæ Ursi; Tormentil. Creosote.)

Tannic Acid, Gallic Acid, and Creosote are the three chief Vegetable

Astringents. To the first two the vegetable substances above enumerated

appear to owe their efficacy. All contain Tannic Acid, or some

modification of it; and Oak-galls contain also Gallic Acid.

The relative efficacy of these active principles may be summed up in a

few words. Tannic and Gallic Acids may generally be used with great

advantage in all cases in which Astringents are required. When applied

externally, Tannic Acid is the most powerful; but for internal

administration Gallic Acid is the best. The reason of this will

presently appear. Creosote, being a powerful Neurotic, cannot be

employed to act on distant parts, but is appropriate in cases of

hæmorrhage from the surface of the stomach.

I have already said that I conceive the astringent powers of these

substances to depend very much upon their chemical affinities. Tannic

Acid precipitates both Albumen and Gelatine. Creosote also coagulates

Albumen. But Gallic Acid does not affect either of them.

Tannic Acid does not seem to be a simple substance. When boiled with

acids, or with alkalies, it yields Gallic Acid and a brown matter.

Tannic and Gallic Acids yield the same set of products when submitted to

destructive distillation. And it appears likely, from the researches of

M. Braconnot, that Tannic is a compound acid consisting of Gallic Acid

in combination with the elements of grape-sugar. Three atoms of Tannic

Acid are together equivalent to six atoms of Gallic Acid and one of

grape-sugar. When the solution of the former acid is heated in the air,

or taken into the human system, the elements of grape-sugar are

oxidized into Carbonic Acid and water, and Gallic Acid is set free.

(_Vide_ Chap. IV. _Art. Tannic Acid_.)

It is thus Gallic Acid which passes out into the secretions, and exerts

an astringent action at distant parts of the system. And as the Tannic

Acid loses weight by the decomposition, it follows that a dose of Gallic

Acid produces a greater effect as a medicine than an equal amount of the

other. Thus one ascertained fact is cleared up by these chemical

considerations, but other mysterious points remain still to be

explained.

Gallic Acid does not precipitate albumen, and is of little use as an

Astringent when applied to external parts; but it is very efficacious

when given internally. Tannic Acid, which is equivalent in composition

to a combination of Gallic Acid with a saccharine matter, is a valuable

external Astringent. A further chemical discovery has been made, which

appears to bear upon these facts. M. Pelletier has found that a mixture

of a solution of Gallic Acid with one of Gum will precipitate albumen,

although neither of them will affect it separately.[43]

Gum has the same composition as common sugar; and grape-sugar, or a

material containing the same elements, is known to be continually

forming in the blood. Thus it is likely that Gallic Acid may act along

with this saccharine matter in the blood, and by this acquire chemically

an astringent power, which it is not able to exert on external parts,

because then isolated. But the saccharine matter is required in the

system for special purposes, and thus Gallic Acid passes out into the

secretions alone.

It seems probable, when Tannic Acid is given, that it is not decomposed

into its constituent parts until it has to be separated from the blood

by the glands.

These two compounds, and the vegetable substances that contain them, are

used in diarrh[oe]a, and in all hæmorrhagic cases. To diminish

sweating, Tannic is inferior to Sulphuric Acid; but to act as a remote

Styptic, it is preferable to the other. Tannic and Gallic Acids diminish

secretions generally; they are very useful in cases of hæmaturia, where

Sulphuric Acid is all but useless.

Creosote is a Sedative, and cannot be well given in such large doses as

to act upon distant parts. In cases of hæmatemesis it acts topically on

the surface of the stomach in a double way, diminishing the hæmorrhage

by its astringent power over the vessels, and quieting the nervous

irritation by which the vascular excitement is often maintained. In

cancerous cases the bleeding can never be permanently stopped.

This concludes the list of Astringent medicines.

Certain stimulant Eliminatives are employed for the purpose of checking

mucous fluxes, and so far simulate the action of true Astringent

medicines. Thus we administer, with more or less advantage, Aromatics in

diarrh[oe]a; Cubebs, Copaiba, and Turpentine, in gonorrh[oe]a; and

Balsam of Peru, and other oleo-resins, in Catarrhal affections. These

medicines all act upon and pass through the glands of the several mucous

surfaces which they affect: while so doing, they stimulate the healthy

function and secretion of the gland, and cause it to displace the morbid

one. Dr. Williams thinks that they first cause dilatation of the vessels

of a gland, and that this is followed by contraction. There is no

apparent reason why the latter effect should succeed the former. But

supposing contraction to take place in this way, then these medicines

would be true Astringents. But it cannot be so, for they do not diminish

any of the natural secretions, but, on the contrary, increase them.

Turpentine, Cubebs, and Copaiba, are Diuretics, and it is possible that

while passing out in the urine they may simply stimulate the mucous

surface of the inflamed urethra, and excite it to a healthy action.

These volatile oils are incapable of exerting a true astringent action.

On the supposition that it is really an Astringent, Turpentine has been

often prescribed as a remedy for hæmorrhages in different parts of the

body. But it has very much disappointed the expectations that were

entertained of its efficacy.

General Stimulants may act indirectly as styptics to a mucous surface,

when relaxed and bleeding on account of an atonic condition of the

nerves by which the contraction of the minute vessels is maintained.

Alcohol, in large quantity, coagulates albumen, and it may thus act as a

true Astringent when applied externally.

Some Neurotic medicines diminish secretions in a way which is not well

understood. The chief of these is Opium, which particularly diminishes

the secretion of the bowels. Attempts have been made to explain this by

an influence possessed by Morphia on the process of Endosmosis, but they

are not satisfactory. Some little light may perhaps be thrown upon the

matter by a consideration of the other operations of Opium; but it is

difficult to explain it decisively in any way.

PROP. X.--_That a fourth class of medicines, called_ ELIMINATIVES, _act

by passing out of the blood through the glands, which they excite to the

performance of their functions_.

In this Fourth Class are included all the medicines which tend in a

direct manner to increase secretion. They have received various

appellations: some authors have called them special Stimulants; others,

as Dr. Duncan, have named them Evacuants; while Dr. Pereira entitles

them Eccritics.

The mode of operation of Eliminative medicines is a matter of

considerable importance, and its consideration will require us first to

make some inquiry into the character and functions of those important

glandular organs which they are said to excite to action.

The rational explanation of the process of elimination or secretion has

been in all ages of science a favourite topic for speculators and

theorists,--sound or unsound in their views, according to the light that

was given to them. With regard to its essential nature, and its

immediate bearing on the cure of disease, the subject has been generally

understood with tolerable clearness. From the time of Hippocrates

downwards, the use of Evacuants in the treatment of fevers and other

disorders has been recognised, and their efficacy usually explained by

supposing that they caused the passage out of the body through the

glands of certain matters that were formed in the blood, but ought not

to remain in it.

This view was more particularly insisted on towards the close of the

seventeenth century by Dr. Thomas Sydenham; and again at the

commencement of the eighteenth by Dr. A. Pitcairn, in an Essay on the

use of Evacuants in Fevers. These both had observed that fevers and

other disorders had mostly a particular tendency to pass off with an

increase in one or more of the secretions; and they drew from this, and

from the results of their experience, that in stimulating and urging

this secretion, the physician would be doing his best to promote a cure.

(_Vide_ page 55.) More recently the same idea has been followed up by

Cullen, Hamilton, and others.

This theory is not in our immediate province. Though based upon

reasonable grounds, it has perhaps been too universally applied. It will

suffice now if we assume that remedies whose action is to increase the

amount of secretion have often an important bearing on the cure of

disease. We have only to inquire into their manner of action. As a

preliminary step, there is one general law of secretion which it is of

importance that we should clearly lay down. It is this: it is the

special office of each gland, or set of glands, to secrete from the

blood particular materials, and to pass them out of the body.[44]

It follows from this law of selective secretion, that when any morbid

substance or product,--or any thing which is in the system, but cannot

naturally remain there,--has to pass out, it prefers to pass by some

glands rather than by others. It must be remembered that the glands

afford the only means by which a substance can make its exit from the

blood. We are still much in the dark as to the _rationale_ of this force

or attraction, by which particular matters are drawn towards each gland.

Dr. Pitcairn, a great man for the age in which he lived,--a man of

original thought and natural genius,--gives us, in his Essay on the

Circulation of the Blood, a learned account of three theories on this

matter which were in vogue at his time. They are of importance, as

showing that the fact was then very clearly recognised, however dubious

the explanation of it might be. One party supposed that there was in

each gland a certain material stored up, which prevented the passage

through to itself of any substance that was not like it; just as when a

sheet of paper is steeped in oil, oil only will pass through it, and not

water. A second party, called the Chymical party, supposed that there

must be in the immediate neighbourhood of each gland a subtle fluid or

ferment, whose tendency and office it was to form and separate from the

blood the materials which that gland had to secrete. A third set of

physicians armed themselves with mathematics and with the newly

discovered principles of Newton, and actually worked out formulæ and

equations wherewith to support their arguments. They had strong and

perhaps reasonable ideas as to the definite shapes of atoms. They

averred that each gland was to be compared to a sieve or strainer,

having in it pores of a particular size and certain geometrical shape,

and that each secreted atom could only pass through a pore that would

exactly coincide in size and figure with itself.

The first two of these theories Dr. Pitcairn disputed, and treated with

high disdain. The third he accepted in a modified form. He supposed that

the vessels in the glands ended in small open mouths, always circular,

but differing in diameter in different glands, so that each would only

admit the passage of a particle whose diameter approached a certain sum.

Thus he supposed that each secretion would consist only of certain

peculiar particles. Possibly Dr. Pitcairn forgot that small particles

would seldom hesitate to pass through large holes.

We may perhaps feel inclined to make light of these crude speculations

of the philosophers of the eighteenth century; we may be disposed to

smile at the idea of vessels with open mouths, and of glands which are

riddled with holes like the buckets of the Naiades; but we must after

all confess that if at the present day we have swept away these notions,

we have certainly added nothing in their stead, nor can we explain this

matter at all more clearly than our predecessors a century and a half

ago.

The fact, however, is plain, however vainly we may try to explain it. It

is an established rule, to which there are few exceptions, that each

substance which is formed in the blood and has to pass out of the body,

tends to pass out through some particular glands; that it is the

particular function of the kidneys to excrete water, urea, uric acid,

and certain salts; that it is the especial office of the bowels to

excrete certain effete matters and gases; and that it is the peculiar

province of the liver to excrete fatty matters, taurine, cholesterine,

and choleate of soda.

Water, being the necessary solvent of the solid matters in all the fluid

secretions, is secreted in greater or less quantity by all the important

glands. The kidneys are the chief emunctories of water,--_i.e._ they

have to separate it from the blood when it has entered in an unnatural

amount. But in the excretion of water there exists a compensating

relation between the skin, kidneys, and bowels,--particularly between

the two former. So that when water is not properly excreted by the

kidneys, it may pass out by the skin, and _vice versâ_. It is well known

that this change may be determined by several circumstances,

particularly by the conditions of heat and cold, or moisture and

dryness. The relation between the function of the skin and kidneys

applies also to other fluid and solid substances, as will be seen when

we consider the medicines which act upon these glands.

Now this law of selective secretion applies not only, as it seems to me,

to substances which in the course of nature are formed in the blood, and

have to be excreted from it, but also to other matters which have been,

as it were, accidentally introduced from without, and which, being in

the system, cannot properly remain there. Thus it would apply to all

medicinal bodies which have passed from the stomach into the blood, and

which, not being natural constituents of that fluid, must again pass out

of it.

So that although it is often laid down that medicines acting on the

glands do so simply by passing along in the blood, and stimulating them

as they go by, I regard this as a needless complication of the subject,

and a thing which is wholly without proof. In fine, I am brought to the

opinion which I have laid down in the Tenth Proposition, and which I

have now to establish as well as my space will permit. The affirmation

may be thus divided into minor propositions:--

_m. p._ 1.--That Eliminatives are medicines which pass into the

blood.

_m. p._ 2.--That they cannot remain there, but must pass out

of the body.

_m. p._ 3.--That in so doing, they tend to pass out by some

glands more than by others.

_m. p._ 4.--That the result of their passage through a gland is

to increase its secretion.

_m. p._ 5.--That they are of use when the state of the system

requires that the function of a gland should be

restored or promoted.

What I wish to prove is, that a medicine increases secretion simply by

being itself secreted; that while passing through a gland it stimulates

the secreting cells, and rouses them to a proper performance of their

natural function; that each eliminative medicine has a tendency towards

particular glands, and increases the secretion of those glands; that

thus, as far as our information on the subject extends, we find that

Cathartics are excreted from the blood by the glands of the bowels, and

pass out with the fæces; that Diuretics are to be discovered in the

urine, Diaphoretics in the sweat, and those Expectorants which are

volatile may be detected in the odour of the breath.

Any material which is naturally eliminated would act as an eliminative

medicine. Thus if a drachm of Urea be dissolved in water, and injected

into the veins of a dog, it causes copious urination, which continues

until the whole is excreted. This well illustrates the argument.

Further, we find that when an eliminative medicine is diverted from the

gland by which it usually passes out, it no longer augments the

secretion of that gland. Dr. Ward gives an interesting case of a woman

who was never purged by Castor-oil, but in whom the oil exuded from the

skin, and acted as a Diaphoretic. And it is, as I have said, well known

that the conditions of cold and exercise will cause a Diaphoretic, in

most cases, to act on the kidneys, because it is then excreted by them.

For the same reason, warmth, confinement, and rest, will induce a

Diuretic medicine to act on the skin.

Thus if it be shown, on the one hand, that Eliminative medicines

themselves pass through the glands whose secretions they augment; and,

on the other hand, that when they do not pass through them, they do not,

as a general rule, augment their secretion,--it may then fairly be

presumed that they operate by so passing through.

I assert, then, that medicines which stimulate secretions are themselves

secreted. But the converse of this--_i.e._ that all medicines which are

secreted at the same time increase secretion,--though it holds good in

the main, is not invariably true. There are two chief exceptions to it.

These are Astringents and Hyperæmics.

When an Astringent passes through a gland, it tends, by its natural

force, to decrease secretion, and to cause constriction of the ducts.

Thus Uvæ Ursi may decrease the amount of the urine, although it

sometimes does the opposite; in which case the eliminative may be said

to surmount the astringent tendency. So also Catechu, Kino, and

Sulphuric Acid, decrease the secretion of the intestinal glands. But

general Astringents are not always glandular Astringents. Thus the

mineral acids act as Diuretics.

By Hyperæmics I mean medicines which produce congestion. Powerful

Eliminatives do this when given in excess, simply by exciting excessive

action. Now it is a general rule that congestion, however caused,

diminishes the secretion of a gland. Thus congestion of the liver

produces jaundice; congestion of the kidney, ischuria. After scarlatina,

when the kidneys are suddenly called upon to eliminate a morbid material

from the blood, congestion of the glands may be caused: the urine is

diminished, and dropsy results.

Cantharides and Turpentine are Diuretics. They increase the urine when

taken in moderate doses; but when in an overdose, they diminish it, and

may cause painful strangury, with an almost total suppression of the

secretion. The explanation of such an action is obvious. Congestion is

caused by the excessive action. In the same way we find that a large

dose of Mercury, naturally a Cholagogue, may produce jaundice, by

causing congestion of the liver. This fact has been observed by Dr.

Graves, of Dublin.

In all cases, then, in which observations have been made, we find that

an Eliminative medicine is secreted by the gland which is stimulated by

it, and, in most cases, that a medicine which is excreted by a gland

tends to increase its particular secretion.

Having made this general statement of the case, I must attempt a more

particular and detailed proof. I will treat in turn of the above minor

propositions, as applicable to the following orders of Eliminative

medicines:--

CLASS IV. ELIMINANTIA.

Ord. 1. Sialagoga.

Ord. 2. Expectorantia.

Ord. 3. Cathartica.

Ord. 4. Cholagoga.

Ord. 5. Diaphoretica.

Ord. 6. Diuretica.

They are enumerated nearly in the order of the glands, from above

downwards, in the human body. I have not enumerated Errhines, because

the medicines which are used to increase the nasal mucus are merely

topical irritants, and not true Eliminatives.

Of Emetics I have already spoken. Some are Neurotics, acting from the

blood on the nervous system; other are local irritants. They also are

not true Eliminatives.

Neither are Emmenagogues so; for the uterus is not a gland. Some of

these too are Neurotics. Most of them act by causing a determination of

blood towards the organ. Cathartics do this by their action on the

contiguous mucous membrane of the intestines. (_Vide_ page 102.)

These then are the six orders of Eliminative medicines. In the first

minor proposition it is stated that they pass into the blood. This has

already been in great part proved; for most Eliminative medicines belong

also to one or more of the preceding classes, of which it has been shown

that they pass into the blood.

Thus Antimony, Mercury, Acids, Alkalies, Sulphur, the Salts, etc., are

Hæmatics primarily. The various volatile oils and resins are more or

less Stimulants. So also Alcohol and Ether, as well as Camphor and

others, are found among Narcotics. Colchicum, Digitalis, Creosote, and

Ipecacuanha, are Sedatives. Many Eliminatives are certainly known to

pass into the blood, because they are subsequently found in the

secretions, as will be presently seen.

Secondly, these medicines cannot remain in the blood, but must sooner or

later leave it. If they remained, they could not pass through the

glandular cells. But if they pass out, they must inevitably be excreted

by them.

All those medicines must be secreted which have nothing in the natural

blood corresponding to them. This is the case with most Eliminatives,

and with all medicines except the Restorative Hæmatics. And those

Restoratives which act as Eliminatives, such as Acids and Alkalies, do

so because they are introduced in so large a quantity that they cannot

possibly remain in healthy blood. Thus all these medicines pass out

through the glands.

Thirdly, we find that in so doing they tend to pass out by some

particular glands rather than by others.

In order to show this we may consider first the chief tendencies of the

great groups of Eliminative medicines; and secondly, I shall endeavour,

when considering the six orders, to show that many of the medicines

included in them have actually been found in the secretions of the

glands towards which they tend. The first consideration will clear the

way for the second. What we have to ascertain is, that the principle of

selective secretion is generally applicable to Eliminative remedies.

The most important of the substances which are used to increase

secretion may be divided chemically under the following six heads, of

all of which it has been proved that they are capable of absorption.

(Prop. II.)

1. Insoluble mineral substances.

2. Soluble minerals,--_i.e._ Acids, Alkalies, and Salts.

3. Ammonia and volatile oils.

4. Fixed acrid oils.

5. Resins and neutral acrid principles.

6. Soluble vegetable principles.

1. _Insoluble mineral substances._--The chief of these are Mercurials

(Blue Pill and Calomel,) Iodine, and Sulphur. They are all more or less

changed during the process of absorption, as they have to be reduced to

a soluble condition. They stimulate secretion generally; but Mercury

particularly tends to the liver, bowels, salivary glands, and skin;

Iodine, to the kidneys, and to the salivary and mucous glands; Sulphur,

to the skin.

2. _Soluble mineral substances._--Acids, Alkalies, and Salts, may pass

off by any of the fluid secretions. The chief of these secretions are

the sweat, the urine, and the secretion of the bowels. The sweat is only

fluid when the skin is kept covered and very warm. In other cases the

choice lies between the kidneys and the bowels. The kidneys are the

grand purifiers of the blood, so that most of the substances which

stimulate the other glands may occasionally pass off in the urine. And

soluble minerals, which require some amount of water for proper

solution, would tend for this reason towards the most fluid of the

secretions.

But there are some other things which counter-balance this tendency.

The constitution of the urine is such that it cannot safely be disturbed

to a very great extent. If there be much excess in it either of acid or

of alkali, a deposit is occasioned. Dr. Bence Jones found that Sulphuric

acid never passed out in the urine in any quantity. We find too that

when a certain quantity of a saline is administered, too great to pass

off readily by the kidneys, it prefers to act on the bowels. It is more

likely to be diuretic if much diluted with water; but this is not the

only directing cause, for a very large quantity of a saline will prove

purgative even when largely diluted. (_Vide_ Prop. II.) Thus the general

rule is this: soluble minerals are in small doses Diuretic, in large

quantity Purgative. This applies more especially to salts; for mineral

acids act as astringents on the bowels,--and mineral alkalies, being

corrosive, cannot be given in large doses.

3. _Ammonia and volatile oil._--The laws of endosmosis favour the

passage of soluble substances through to a liquid secretion. They are

dissolved and carried away on the other side of the membrane through

which they pass. In the same way it appears that volatile substances may

dissolve in, and be carried away by, air. Thus they have a tendency

towards the aeriform secretions. These are,--the expired air, or the

secretion of the air-cells of the lungs,--and the ordinary cutaneous

transpiration. While passing through the air-cells, these matters

stimulate the secretion of the lining mucous membrane. They cause a

morbid secretion of this surface to be replaced by a more natural one.

Thus Ammonia and volatile oils are Expectorant and Diaphoretic. They may

all pass out in the urine, but do not especially tend to do so, with the

exception of some that are acrid, and approach to the nature of the

resinous group. Turpentine, Juniper, and Copaiba, are Diuretic.

4. _Acrid fixed oils._--Such are Castor and Croton Oils; they are

Purgatives, passing off by the bowels.

5. _Resinous and neutral acrid principles._--These are soluble in

alkalies, and thus partly absorbed in the intestinal canal. Most of them

are Cathartic, whether introduced into the stomach or injected into the

veins. Such are the resins of Scammony, Jalap, and Gamboge, and the

principles of Colocynth and Elaterium. Some few of them are Diaphoretic,

as Guaiacum and Mezereon. Some again are Diuretic, especially those

which are liquid or associated with a volatile oil, which is the case

with Copaiba, Cubebs, Cantharides, and others.

6. _Vegetable principles soluble in water._--Most of these are Diuretic;

as are the Vegetable Acids, and the Alkaloids of Digitalis, Tobacco, and

Colchicum. So also are the principles of Broom and Sarsaparilla. The

Emetine in Ipecacuanha, and the Morphia in Opium, act on the skin.

Aloesin, the principle of Aloes, is purgative. So is Cathartin, the

soluble acrid principle of Senna.

Having thus briefly sketched out the particular tendencies in the

operation of the groups of medicines which act on the glands, it remains

for me to say that in very many cases these medicines have actually been

proved to pass out of the body by the glands whose secretions they tend

to increase. Whenever we are in a position to inquire into the facts by

chemical or other means, we find that the Eliminative medicine is itself

contained in the secretion which is augmented by its action, and that

when the secretion upon which it usually acts is not augmented, the

medicine has passed off by some other secretion instead. There are

doubtless many cases in which no inquiry of the kind has been yet made;

but it will be seen when we consider separately the Eliminative orders,

that all that is known on the subject is in favour of the above

statement.

Assuming, then, the third and fourth minor propositions together, we

conclude that Eliminative medicines, which must pass out of the blood,

tend to pass out by some glands more than by others, and that the

result of their passage through a gland is to increase its secretion.

They do not exert a blood-influence, nor do they act on the nervous

functions; but they operate on those obscure vital forces by which

secretion is directed and controlled.

The fifth minor proposition treats of the application of these agents in

the treatment of disease. They are of use when it is requisite that the

function of a gland should be restored or promoted. There is scarcely

any disease in which some or other of them may not be of service. Their

remedial applications are many and important.

Eliminatives are used to restore the function of a gland when impaired.

With this view, Cathartics are employed in constipation, Diaphoretics

for dryness of skin, Cholagogues in torpid states of the liver.

They may eliminate a poison or morbid material, and thus resolve a

disease. This probably is the rational explanation of the use of

Diaphoretics and Diuretics in Fevers, Gout, and Rheumatism, and of

purgative medicines in a great number of disorders.

We may, by an action on one gland, be enabled to replace the function of

another gland. The amount of each secretion bears more or less an

inverse proportion to that of other secretions. Thus when one of them is

unduly copious, we may diminish it by stimulating the formation of

another. In other cases the reverse condition may occur; one of the

secretions may be diminished or suppressed by a cause over which we have

no control, and the matters which should be contained in it may be left

in the blood, causing various mischief there. Here again, by increasing

one of the other secretions, we may replace the function of the diseased

gland, and cause the elimination of these products from the body by

another channel.

Fourthly, Eliminative medicines may be of service by draining away from

the blood fluid and solid matters. The first result of their action is

to stimulate the proper secretion of a gland; but when it is pushed to a

further extent, they may actually case the excretion of some of the

natural constituents of the blood. Thus by an action on the skin or the

kidneys, we may cause a copious evacuation of water, holding in solution

saline matters. By increasing the secretion of the intestinal glands, we

may cause the albuminous serum of the blood to be poured out into the

cavity of the bowels. Thus it is that all Eliminatives are more or less

antiphlogistic. Cathartics are especially so. Their influence, when

carried to excess, is analogous to that of blood-letting. As evacuants,

Cathartics are employed in diseases of the brain especially; and

Diuretics are made use of in dropsies to diminish the amount of fluid in

the blood, and in this way to promote absorption.

So much having been said of the general action of Eliminatives, we

proceed to make a few remarks on the individual orders of medicines

which are included in this division. Those substances can alone be

properly included in these groups which really act on the principle of

elimination, as above defined. There are in many instances other

medicines which are found to increase secretion in an indirect way.

ORD I. SIALAGOGUES.[45]

This name is applied to medicines which in various ways increase the

quantity or promote the excretion of the saliva. They are seldom

employed as remedial agents; for the excretion of saliva is constant and

very rarely suppressed, and it is so small in quantity, and so great a

source of inconvenience when increased to any amount, that Sialagogues

can never be employed as general evacuants. There are two kinds of

Sialagogues.

Any solid substance which excites the mucous surface of the mouth, as

the natural food,--or even the act of mastication alone,--will suffice

to bring on the secretion of saliva. An irritant substance, as Ginger,

or Pyrethrum, tends especially to cause this secretion when masticated.

Catechu and Betelleaf are chewed for this purpose by the natives of the

East.

Such a stimulation of the salivary glands may be advantageously resorted

to on the counter-irritant principle in obstinate cases of head-ache,

ear-ache, or tooth-ache, or in neuralgic or chronic rheumatic affections

of the face.

When the quantity of the saliva is thus increased, it should not be

rejected, but always swallowed when possible; for this secretion is

apparently useful in the stomach, and in some way essential to the

proper carrying on of the digestive process. The chewing of Tobacco,

Betel, and other substances, is frequently found useful by sailors on

long voyages, and is adopted as a preservative against the dysentery and

diarrh[oe]a with which they are so often affected. This advantage is to

be attributed to the increase in the salivary secretion. On the other

hand, we find that the practice of constant spitting is productive of

very injurious effects; and it is more than possible that the pale

faces, lank figures, and dyspeptic maladies, which are so common among

the American people, may be due in part to the prevalence of this habit

among them.

These topical irritants and masticatories are not true Eliminatives.

There are also some medicines which by another topical action may

occasionally produce salivation. These are Sedatives. Hydrocyanic acid,

Digitalis, and nauseant medicines, may act locally so as to paralyze the

muscular fibres by which the constriction of the salivary ducts is

maintained, and thus allow the secretion to pour out uncontrolled into

the cavity of the mouth.

_True or Eliminant Sialagogues._--These are medicines which are actually

excreted from the blood by the salivary glands, and which increase their

natural secretion while passing through them. Mercury is the most

important of these. When given to a considerable extent, it causes

soreness and redness of the gums, and profuse salivation. It probably

increases the amount of saliva even before this soreness is produced. It

is not given for the purpose of producing salivation, but in cases where

the full action of Mercury is desired this symptom is made use of as a

sign that the medicine has taken full effect upon the system. If we

permit it to be carried to too great an extent, sloughing of the gums

and other dangerous results may be produced.

In some rare cases salivation has followed the administration of Iodine.

It is also not an unfrequent symptom of chronic poisoning by Lead. In

cases of salivation by these Eliminative medicines, the substance which

has caused the increased secretion may be, and has been, discovered in

the saliva by chemical tests. They are therefore true Sialagogues.

ORD. II. EXPECTORANTS.

This term, when taken in its widest sense, is applied to all medicines

that cause the evacuation of mucus from the secreting surface of the

respiratory tubes and cavities. They help the natural process of

Expectoration.

Many medicines are capable of acting indirectly as Expectorants. Any

thing which causes cough, as an irritant gas, will do it. So will any

thing that thins the mucus when thick and viscid,--_e.g._ the

inspiration of the vapour of hot water. Special Sedatives, which control

the function of the Vagus nerve, are especially notable as indirect

Expectorants. Such are Antimony and Ipecacuanha. By diminishing the

morbid irritability of the pulmonary surface, they prevent the continued

secretion of mucus. By allaying a spasm of the small bronchial tubes,

and controlling the nervous sensation of want of breath, they may

promote the evacuation of that which is already secreted.

Opium and Stramonium, classed among Narcotics, depress the function of

this nerve as well as the nervous forces generally. So do other

medicines similar to them. Opium in small doses allays irritability and

diminishes spasm, and is then an indirect Expectorant; but in large

doses it acts so powerfully as to render respiration difficult and

expectoration impossible. Its use therefore demands great caution.

_True Expectorants._--The action of Antimony and Ipecacuanha upon the

secretion of bronchial mucus is of so specific a character as to render

it highly probable that these medicines add to their neurotic influence

a true eliminative agency. We are as yet unable to decide whether or not

they are ever secreted by these mucous glands, because not only is the

analysis of the mucus a matter of difficulty, but hitherto no

investigation of the matter has been made. Squill also is probably an

Eliminative Expectorant.

Many of the true Expectorants are volatile and odorous in nature. All

excreted substances have to pass by an endosmotic process through a thin

animal membrane. And it is necessary before they can pass, that there

should be on the other side of this membrane something which is capable

of dissolving them. Diuretics are soluble in water, and they pass

through into a watery fluid. But these Expectorants, whether they pass

through the mucous glands, or immediately through the thin wall of the

lung-cell, are brought directly into contact with air. And in this air

these volatile matters are soluble, and are carried away by it.

This appears to be the reason why the Eliminatives which are volatile in

nature tend particularly to act on the two aeriform secretions,--_i.e._

on that of the air-cells of the lungs, and on the common cutaneous

transpiration. For though the glands of the mucous membrane of the

lungs secrete mucus, yet the chief object of the terminal portion of

that membrane is to absorb and secrete the gaseous matters of the blood.

The following are the chief volatile Expectorants, the odours of which

have been clearly detected in the breath of persons to whom they have

been administered:--Turpentine, Camphor, Alcohol, Ether, and the

volatile oils of Onions, Fennel, Asaf[oe]tida, Carraway, Cinnamon, and

Anise.

These medicines, and others like them, are thus excreted by the

air-cells or mucous glands of the pulmonary surface, and while thus

passing through they stimulate the latter to a right performance of

their function. When, as in the case of Bronchitis, the secretion of

mucus is increased in amount, or deteriorated into a purulent matter,

they may be of service by causing the healthy secretion to replace the

diseased one.

Expectorants are very uncertain agents. The reason of this is, that the

pulmonary glands are not naturally intended to act as emunctories, or

dischargers of morbid matters from the blood, and thus are less prone to

be excited by Eliminative medicines than other glands whose proper

office is one of general elimination. And yet we find that the effete

gases which should be excreted by the bowels are sometimes voided by the

lungs in case of aggravated dyspepsia, causing tainted breath. Just so

may other adventitious elements of the blood, as these volatile

medicines, be sometimes excreted by the pulmonary membrane. But they may

often pass off by the skin or by the urine, and would not then act upon

the lungs at all.

For the same reason that the lungs are not general emunctories, and

cannot be made use of to produce a wholesale evacuation from the blood,

Expectorants are of no use as general Antiphlogistics. In this they

differ from the four remaining groups of Eliminatives.

They are only employed in pulmonary disorders, where we desire to

influence the amount or character of the mucous secretion, when the

mucous membrane is inflamed or irritated. In old and chronic cases of

Bronchitis the stimulant volatile Expectorants are the most applicable.

Tartar Emetic and Ipecacuanha are appropriate in acute and inflammatory

cases, because they exert a nauseating and depressing action. They are

sometimes given in sufficient dose to act as Emetics; for the act of

vomiting mechanically assists the expulsion of mucus from the air-cells

and passages by causing straining and compression of the lungs.

ORD. III. CATHARTICS.

Cathartics are medicines which tend to increase the secretion from the

inner surface of the bowels, and promote the natural expulsion of the

contents of the intestinal tube. Of these two operations the first only

is an action of elimination, and the second is an accompaniment to it.

The first can hardly take place without being followed by the second;

but in some few cases the second action alone may be produced.

The subject of the application of Purgative medicines is so extensive,

that it is impossible for us now to inquire into it at any great length.

It should however be observed, that they are the most powerful and the

most useful of all Eliminative medicines. The fæces consist partly of

the undigested matters of the food, and partly of a secretion which is

poured out by the inner surface of the bowel. (_Vide infra._) The

majority of Cathartics increase this secretion. Whatever notion we may

adopt as to its physiological purpose, it appears that we can act upon

this intestinal function with ease and certainty in the great majority

of cases. The surface of the intestine, covered as it is with a closely

packed glandular apparatus, forms in the aggregate the largest secreting

organ in the body. From the measurements made by Meckel, it appears that

it covers a space of 1400 square inches. By the administration of a

medicine of this sort, we are enabled to act upon this surface,

producing simply an increase of the fæcal secretion, or causing, when

the action is violent, an outpouring even of the fluid part of the

blood. When this secretion is stopped, we may cause it to reappear; when

another secretion is repressed, we may be enabled to replace it by this;

and in the treatment of plethoric or inflammatory disorders, we find

among Cathartics the simplest and readiest of antiphlogistic or evacuant

medicines. For they possess these great advantages,--that they act with

certainty, and produce a notable effect.

All medicines which by a mere external action augment the secretion of

the bowels, or promote its evacuation, must be regarded as _indirect_

Cathartics, for they do not operate on the eliminative principle. An

outward irritation of the mucous membrane is sufficient to excite the

peristaltic contraction of the bowel, and may even increase the

secretion of that mucous surface by a reflex nervous action, in the same

way that an irritation of the mucous lining of the mouth will cause the

secretion of the saliva. All substances which, after being taken into

the stomach, are not absorbed, which are thus pushed onwards along the

inner coat of the intestine, and by their mere accumulation excite its

muscular contraction, must operate more or less as indirect purgatives.

Of such a nature are the ligneous fibres of vegetables,--the bulky pulp

of fruits, as in Prunes, Tamarinds, and Cassia,--and the husk of wheat

in brown bread,--all of which are known to act as laxatives. Very

different from these in the intensity of their action are the resinous

Cathartics, as Scammony and Gamboge, which, though capable of

absorption, appear also to act in some cases by an external irritation

of the intestinal surface. They are also true Eliminatives, for they are

known to become absorbed; they may thus act in a double way, both

directly and indirectly. (_Vide_ p. 96.) In small doses it is probable

that they are simply Eliminatives, but when given in large doses they

may add to that an irritant external action, and produce a very powerful

or even dangerous effect.

_True Cathartics._--These are very many in number. At whatever part of

the system they are introduced, their action is the same. If one of them

be injected in solution into the veins, or absorbed from the surface of

the skin, it passes at length to the intestinal canal, is excreted by

the glands of the mucous surface, and causes purging by augmenting their

natural secretion. When given as a medicine, the Cathartic is first

received into the stomach. It is capable of absorption,--whether it be

soluble in water, or in acid, or be of an oily or resinous nature,--as

was ascertained in the consideration of Proposition II. It is absorbed;

and passes along in the circulation. But it is unnatural to the blood,

and cannot remain in it; so that it is at length expelled by the

eliminative force at the lower part of the intestinal canal, at a part

which is more active in excretion than in absorption, though not very

remote from the absorbent surface at which the remedy first entered.

Cathartics may be advantageously divided into three groups:--1.

Mercurials, which tend to increase all secretions; 2. Some resins, oils,

and acrid principles, which tend especially to the bowels; and 3.

Salines, when given in such amount that they cannot pass off by the

kidneys.

Mercurials, being also Cholagogues, are especially useful in bilious

habits. When given to act on the bowels, a Mercurial is generally

conjoined with another purgative, that it may not do damage in the

system by remaining in the blood.

In the second group the great majority of Cathartics are included. They

vary very much in the intensity of their action. Some are mild, and may

be administered in inflammations and fevers, or even in pregnancy, where

a gentle action is required; others are powerful and drastic, and may

cause serious congestion, or even inflammation of the bowel. All the

resins and acrid principles are more or less heating, and should be

administered very carefully in febrile states of the system. Of the

resins, Jalap is comparatively mild, and may be given to children

without risk; while Scammony, Colocynth, and Gamboge are more drastic.

Of the oils, Olive-oil is merely laxative; Castor-oil may be given in

all cases without danger; but Croton oil is a dangerous hydragogue

Cathartic. Of the medicines which owe their efficacy to acrid

principles, there are some which are mild in operation, and whose

principles are soluble in Water. Such are Rhubarb, Aloes, and Senna.

Senna is somewhat irritant. Aloes appears to act on the lower part of

the intestine, and is therefore objectionable in cases of pregnancy or

of uterine disorder. Hellebore is a more powerful acrid, but is now

seldom used. Elaterium is the most potent purgative known. In cases of

dropsy, when all other medicines have failed, one-twelfth of a grain of

this substance has been known to produce a copious evacuation.

Salines, _i.e._ salts of the alkaline and earthy metals, are all more or

less purgative when given under certain conditions. Under other

circumstances they may pass off from the body by the kidneys or the

glands of the skin. The circumstances which determine the excretion of

saline matters appear to be simple in nature. In the common condition of

the body it is not possible for the secretion of the skin to be very

largely increased, or rendered fluid. Suppose, then, a soluble saline,

as the Sulphate of Soda or Magnesia, or Tartarized Soda, to have

obtained entry into the blood, it has the choice of being excreted by

the kidneys or the bowels. The alternative appears to depend mainly upon

the amount of the dose. A small quantity may pass in the urine, and will

not produce purging. But a large quantity cannot so pass; it is excreted

by the glands of the bowels, and acts as a Purgative. It has been

supposed by some that a saline solution proves Purgative or Diuretic

according to the degree of its dilution only. This matter we have

already considered at some length; and the reasons which have induced me

to arrive at a contrary conclusion have been detailed under the head of

Proposition II.

Salines are hydragogue. Requiring water for their proper solution, and

having further a great affinity for it, they convey a large quantity of

the aqueous part of the blood with them through the glands of the

bowels. When their action is very powerful, some of the albumen of the

blood may be purged away along with this. This may also take place with

the drastic resinous Cathartics. But the latter are much more violent in

their action, producing a degree of griping and irritation which is

dangerous in febrile cases. Salines, on the contrary, are cooling, and

mild in their operation. They are appropriate in inflammations, not only

for this reason, but because, while passing through the blood, they

exert in it, as we have already seen, a mild action of an antiphlogistic

nature. (_Vide_ page 188.)

When the vegetable salts of the alkalies are given in diuretic doses

they are decomposed into carbonates while in the system. This does not

appear to be the case when they are given in such quantity as to pass

off quickly by the bowels.

These various Cathartic medicines are affirmed to act on the eliminative

principle: it follows then that they must themselves pass out of the

body along with the secretion which is augmented by their action. It is

natural that the fæces should have been less examined than other

secretions. The resins of Jalap, Scammony, and other such substances,

are affirmed to pass out along with them. Of the passage of saline

Purgatives we have an indirect proof; which is, that after their

administration the amount of saline matter in the urine is not

materially increased. Castor-oil is seen in the evacuations, sometimes

little altered, at other times in the form of a solid fatty substance.

M. Lehmann has detected Mercury in the fæces, whenever it was given as a

Purgative, and whatever the colour of the evacuation. When combined with

a sufficient amount of Opium, it neither acts as a Purgative, nor does

it pass out by the bowels; and it has therefore in that case a better

opportunity of exerting its operation in the blood. We always find that

when a Cathartic passes off in some other way than by the glands of the

bowels, it fails to produce purging. Thus a copious dilution with water

may sometimes cause it to be excreted by the kidneys, which are the

natural emunctories of water. In some persons that are wont to perspire

very freely it is difficult to produce purging. The case related by Dr.

Ward of a woman with whom a dose of Castor-oil was seen to pass off by

the skin, and invariably failed to act on the bowels, is an extreme

instance of this kind.

Of what use and intention, we may now venture to ask, is this intestinal

function, the continual maintenance of which in a healthy condition is

found to be so essential?

It was some time ago supposed that the fæces consisted simply of those

parts of the food which remained unabsorbed, and that all Purgative

medicines alike acted by exciting the peristaltic motion of the bowels,

and causing thus the ejection of these undigested matters. Such an

opinion is now rarely maintained. Although very little is known of the

separate functions of the glands of the intestinal mucous membrane, yet

it is generally supposed that the fæcal matters consist in great part of

excrementitious substances which are separated by their means from the

blood. The excretion of fæces continues when no food is taken. It is

known to go on with starving men, and with patients in fever. Liebig

argues for the secretion of the greater part of the fæces, on the ground

that they contain nitrogenous matters, whereas all the nitrogenous parts

of the food should be absorbed for the purposes of nutrition. Thus these

are probably the excreted products of changes in the system, which it

is the province of the bowels to separate from the blood. (_Anim. Chem._

p. 156.) The odour of these matters is partly owing to sulphuretted

hydrogen, or hydrosulphate of ammonia, both of which are the products of

animal decomposition. On account of their presence a black colour is

communicated to the fæces by the internal administration of the salts of

Iron.

It seems to me to be probable that the constituents of the living as

well as of the dead body are constantly subjected to the control of

chemical laws, and undergoing destruction and change. Some products of

these changes in an early stage are eliminated in the urine; but in

great part they go on to actual putrefaction. The products of this,

which are of an offensive character, are apparently discharged from the

body through the follicles and glands of the intestines. We find that

this decomposition is promoted and accelerated by heat, in the same way

as with dead animal matter. For this reason it appears that the natives

of warm climates excrete a much larger quantity of fæces than the

dwellers in colder latitudes; and they are also more subject to

Dysentery, Diarrh[oe]a, and Cholera, on account of the extra work thrown

upon their intestines. A similar explanation may perhaps be assigned to

a curious fact noticed some time ago by Mr. Curling--viz., that acute

ulceration of the duodenum is a frequent consequence of severe

superficial burns. A quantity of gangrenous or decomposing matter may in

such a case be carried from the surface into the circulation.

This blood-decomposition, which I suppose to be always going on, may be

accelerated by the action of certain morbid poisons or processes. The

secretion of the bowels is then increased, and by the excitement or

over-work a diseased condition of the intestinal surface may be

established. In this way the diarrh[oe]a and ulceration of the glands in

Typhoid fever may be accounted for. The air of a dissecting-room, or

the neighbourhood of a noxious sewer, is apt to bring on diarrh[oe]a by

exciting a putrefaction of the blood. Severe bodily exercise, as a long

walk, may cause it, by increasing the waste of tissue. We find that

constipation is commonest in youth, when nutrition is most active; and

diarrh[oe]a most frequent in old age, when waste and decay go on the

fastest.

When these decomposed matters which should be excreted, are retained in

the blood, as is the case in constipation, they affect very injuriously

both the brain and the system in general, causing torpidity of the one,

and in the other favouring the progress and development of every

description of morbid action. It is by cleaning such matters out of the

blood, as well as by their antiphlogistic or evacuant action, that

Cathartics become useful in so many diseases, and particularly in

disorders of the brain. It would seem that the substances which would be

eliminated by the bowels have, when retained in the blood, a peculiar

action in the aggravation of disorders of this latter organ. Thus from

very early times the exhibition of drastic purgatives, particularly

Hellebore, has been strongly recommended in cases of mania.

But there is scarcely any disorder in which there is not, in some way or

other, a deranged condition of the intestinal function, and in which,

therefore, the judicious employment of purgative medicines is not at

some time necessary. Either there is constipation, in which case there

is a danger of the fæcal matters being retained in the blood; or there

is diarrh[oe]a, which is probably due to an over-formation of these

materials in the system, and an attempt of nature at their evacuation.

In each of these cases Cathartics may be necessary. The first condition

is the more obstinate of the two; the second the more immediately

dangerous. Some general indications for their treatment may be alluded

to.

In the treatment of constipated habits it is better to keep up a

constant and gentle action on the bowels than to give violent doses

occasionally. A condition of this sort may sometimes co-exist with

comparative health, and may then often be remedied by a slight

alteration in diet, and the prescription of such kinds of food as are

more relaxing in their nature than those hitherto taken. Dr. Hamilton,

in his work on Purgative Medicines, states that when they are given in

constipation he has found that they become more and more powerful, and

may be taken in smaller and smaller doses the longer they are continued.

This is probably the case with such as Castor-oil, Scammony, and Jalap,

which are simply cathartic in their action. But others, such as Rhubarb

and Aloes, contain a bitter and astringent matter along with the

purgative principle, and though they first act upon the bowels tend for

this reason in the second place to confine them. Thus while the former

are best in cases of constipation, the latter are preferable in

diarrh[oe]a, as they supply us then with the very action which we

require.

There are two ways, apparently opposite and inconsistent, of treating a

flux from the bowels. We may try to encourage it by Purgatives; or

attempt to suppress it by Astringents. Thus we may treat a common

diarrh[oe]a by Castor-oil, or by Sulphuric Acid. In dysentery we may

give Calomel, or Catechu. Even in Cholera some recommend Opium, while

others have employed Croton-oil. In the most obvious case, _i.e._ in

simple diarrh[oe]a, it is apparent that both plans are appropriate, but

at different periods of the disorder. The symptom depends upon the fact

of something being formed in the blood which ought to be excreted from

it. Probably it is an excess of that material which is ordinarily

excreted by the bowels. Its passage out by a natural effort causes at

first a simple increase of the usual evacuation. It is at this time that

we should give a Purgative, to favour the natural excretion, and thus,

if possible, to put an end to the disturbance. But sometimes it fails to

do so. The matters to be excreted are irritating, and such an

excitement may be caused in the glands by their passage out, that even

after this necessary secretion an inordinate and unnatural flux may be

maintained. When the symptom is thus inveterate, and refuses to yield to

a brisk Cathartic, it is advisable to resort to Astringents, in order to

put a speedy stop to the too copious secretion. To do this in the first

instance would have been wrong, except in special instances,--as in the

diarrh[oe]a which is the forerunner of cholera, when Astringents should

be used from the first.

In some febrile and plethoric cases it is difficult to obtain the full

action of a Purgative. This is because the absorption of the medicine is

prevented by the pressure on the vascular system, and without this

absorption the proper action of the Purgative cannot take place, for it

has no opportunity of passing out of the blood through the glands of the

bowels. In such instances it is well to combine the Cathartic with a

small dose of Tartar Emetic or Ipecacuanha, which by its nauseant

operation may diminish the vascular pressure, and thus favour the

necessary absorption. The action of a Cathartic itself favours

absorption, by draining away the fluid part of the blood, and so

diminishing the tenseness of the vessels.

ORD. IV. CHOLAGOQUES.

Medicines which are thought to stimulate the action of the liver, and to

promote the excretion of bile, are called Cholagogues.

There is no doubt that the function of the liver, regarded simply as a

gland, is of great importance in the animal economy. We know that

certain matters are excreted from the system by that organ, which, when

allowed to remain in the blood, as in the case of jaundice, are found to

be hurtful. Also it appears that certain other parts of the bile are

secreted or formed by the same gland, for the purpose of being

re-absorbed into the blood from the intestine, and that they serve some

useful purpose in the processes which go on in the circulation. (_Vide_

p. 137.)

A disorder of the liver by itself, _i.e._ unassociated with diseases of

other organs, is comparatively uncommon. A failure in the secretion of

bile is evidenced more or less by the well known icteric symptoms.

Jaundice is often caused by an obstruction in the hepatic ducts. In such

cases it is worse than useless to urge the liver to an extra formation

of a secretion which can find no outlet. But other cases, in which the

discoloration of the skin is in general incomplete, may be due to

torpidity, congestion, or chronic inflammation of the organ. In such

instances Cholagogues may be cautiously used; but when there is acute

inflammation they may do harm; and when there is a probability of

structural change in the liver, they may be useless.

The great majority of intestinal diseases, as also of chronic

blood-disorders, are associated with a torpidity or derangement of the

function of the liver. We find this to be the case with diarrh[oe]a and

constipation, with dysentery and cholera; as well as with ague and

remittents,--gout, and rheumatism,--Phthisis, and scrofula. In all of

these diseases it is of great importance to attend to the state of the

liver. I have already stated that Quina and other Tonics are of very

particular use in such cases of disorder of the hepatic functions, and

have attempted to discover an explanation of this fact (p. 142.) But we

are at present concerned with medicines which tend immediately to

increase the secretion of bile. They are more or less applicable in all

the disorders which have just been enumerated. All Cathartic medicines

act as indirect Cholagogues. This is particularly the case with the

drastic purgatives. There appears to be a vital connexion between the

action of the intestinal canal and that of the liver, so that any

process going on in the one will excite the function of the other. Thus

the bile is poured out during the process of digestion; and the

peristaltic motion and extra-secretion, produced in the bowel by the

action of a purge, causes likewise a sympathetic formation and excretion

of bile. It is supposed by some that this result is due to an irritation

of the orifice of the hepatic duct in the duodenum, produced by the

purgative medicine. We must either suppose the stimulus of the food,

which produces the same effect, to operate in the same way,--or reject

such an explanation as superfluous, which appears to me the better

alternative. For it is probable that the action of a Purgative is not at

all exerted in the duodenum, but that it is actually absorbed there, and

works out its operation in the lower part of the small and in the large

intestine.

_True Cholagogues._--We are not well informed as to the exact number of

medicines which pass out into the secretion of bile, and act thus on the

true eliminative plan. But there is no medicine which is of such great

and universal utility in all liver diseases as Mercury,--in its various

forms. Mercurials increase more or less all secretions; and even if we

had no direct proof of their action on the liver, we might almost have

affirmed that they especially increased the secretion of bile, from the

obvious way in which bilious symptoms yield to their action. But we have

a direct proof of this. M. Buchheim has made some careful experiments on

a dog. Having given it Mercury, he cut down upon the hepatic duct,

observed and collected the secretion, and subsequently analyzed it. He

found that the bile was increased, and that Mercury was contained in it.

(_Vide_ p. 275.) Certain other purgative medicines are popularly, and

perhaps correctly, esteemed as specific Cholagogues. These are Rhubarb

and Aloes. Taraxacum is also thought to act upon the liver. But of the

true eliminative action of these medicines we have no proof.

It is probable that alkalies and fatty matters may act in certain cases

as true Cholagogues, for they are both contained in the natural

secretion of bile, and therefore likely to pass into it.

In many cases of debility, and even of Scrofula, small doses of Mercury

may act efficiently as tonics, by stimulating the function of the liver,

which in such instances is generally deranged.

ORD. V. DIAPHORETICS.

These are medicines which tend to promote the secretion and exhalation

from the surface of the skin. Of the matters which are given off from

the surface of the body there are three kinds. Water in the state of

insensible vapour, and volatile matters, are continually exhaling from

the skin at all points, and pass unnoticed into the atmosphere around.

The liquid sweat, which in the ordinary state of the body is only given

off in sufficient amount to prevent the skin from becoming over-dry, is

secreted by the sudoriferous glands, whose ducts terminate in large

numbers on the surface at every part. There is in the third place an

oily material, formed for a similar purpose by the sebaceous glands,

which are widely distributed, but fewer in number than the last.

Diaphoretics seem to increase only the first two kinds, viz., the

aeriform transpiration, and the liquid sweat; and they act upon these in

a varying proportion. In the consideration of this order we have not

only to bear in mind the distinction between these two kinds of

diaphoresis, but to note further the important relations existing

between the action of these medicines and the state of the atmosphere,

the condition of the body, and amount of other secretions.

In all relaxed conditions of the general system, the amount of the

perspiration is apt to be increased. This is especially evident in the

weakness which follows a paroxysm of simple fever. The force of the

heart is weakened, the tone of the capillaries impaired,--and by these

conditions absorption is favoured, and the amount of fluid in the blood

increased. At the same time the muscular system is relaxed, and the

sudoriferous ducts being thrown open by the diminished contraction of

the involuntary fibre that surrounds them, the excretion of the sweat is

favoured, and the watery parts of the blood are poured out through the

skin. This general relaxation precedes and follows the act of vomiting,

as induced by a dose of Tartar Emetic or Ipecacuanha. Thus these

medicines act indirectly as Diaphoretics, when given in emetic doses.

_True Diaphoretics._--The following groups of medicines may be briefly

noticed as tending to act as Eliminatives on the glands of the skin.

Five divisions may be made:--1. Salines and diluents, under certain

conditions; 2. Volatile substances which are soluble in air, as Ammonia,

volatile oils, and Alcohol; 3. Certain acrid matters, as Guaiacum; 4.

Certain Narcotics, as Opium and Camphor; 5. Antimony, Mercury, and

Sulphur.

These Diaphoretics are all more or less uncertain in their action, as we

have seen to be the case with Expectorants. There are two causes of this

uncertainty. In the first place, the secretion of sweat, like that of

the lungs, cannot be considered as a common emunctory. There are hardly

any solid matters in it which are not also contained in the urine, and

commonly excreted by the kidneys. It is only in special cases, or when

there is a fault in the normal formation of urine, that the skin is

called upon to eliminate materials from the blood.

In the second place, there are certain atmospheric and other conditions

which promote the secretion of sweat, and certain others of an opposite

nature which tend to retard it, and to divert into another channel the

aqueous materials which should pass into it. With regard to the state of

the atmosphere, warmth favours diaphoresis, cold repels it. Warm dry

air, especially when in motion, promotes the aeriform transpiration, by

favouring evaporation. Moist air, which hinders evaporation, promotes

liquid sweating. Very active exercise, with the surface warmly clad,

produces liquid perspiration. Moderate exercise, with a cool surface,

favours diuresis. The recumbent posture, and sleep, promote diaphoresis;

the erect posture and wakefulness, diuresis. Thus when it is required to

produce sweating, the patient is ordered to lie in bed, to be covered

warmly, and to compose himself to sleep. Any thing which keeps the

surface of the skin unnaturally warm, as a hot-air or hot-vapour

bath,--or thick flannel clothing, which is a non-conductor of

heat,--tends powerfully to cause diaphoresis. So does friction, which

stimulates and dilates the external capillaries.

So far the conditions of sweating and of diuresis are nearly opposite.

But this is not the case with the medicines which are used to cause

them.

Diluents, and salines soluble in water, form the first group of true

Diaphoretics. Water promotes alike the function of the skin and of the

kidneys; and it is only by a regulation of the circumstances mentioned

above that it can be diverted from the latter towards the former.

Diluent drinks are indispensable adjuncts to a Diaphoretic regimen.

Salines also tend naturally to pass off in the urine, when in small

doses; but when in large amount, by the bowels. A saline, being soluble

in water, cannot pass out except into a fluid secretion; so that a

saline diaphoretic should be given in a moderate dose, and to secure its

action the skin should be kept covered and warm, and the patient in a

recumbent posture. The medicine will then pass off into the liquid

sweat, as it otherwise would have passed into the urine.

Volatile Diaphoretics may increase the cutaneous transpiration, and pass

off by the skin, without the production of sensible liquid sweating. For

being soluble in air, and capable of being carried away by it, they

therefore tend especially to the two aeriform secretions, _i.e._ those

of the lungs and of the cutaneous surface. (_Vide_ pp. 278, 285.)

Ammonia and its various salts are very useful as Diaphoretics. Volatile

oils are less energetic, for they often pass off with such ease as not

sensibly to increase the secretion of the skin.

Some acrid matters, as Guaiacum, Mezereon, and Senega, appear to act

specifically on the function of the skin. So also do certain Narcotics,

among which Opium is conspicuous as the most certain Diaphoretic that we

possess, though its other operations prevent it from being applicable in

all cases.

Antimony, Mercury, and Sulphur, are medicines which appear to a greater

or less degree to increase all the secretions in the body. When given in

the insoluble form, they are reduced by the system to a soluble state.

When Tartar Emetic is given in small doses, its only apparent action is

slightly to increase the perspiration. It is probable that it then

passes out through the glands of the skin. When given in emetic doses,

it may produce sweating indirectly, as mentioned above. Iodine, which

also increases secretion generally, acts sometimes as a Diaphoretic.

Many volatile oils have been detected by their odour in the

perspiration, as those of Garlic, Onion, Asaf[oe]tida, Musk, and

Copaiba. Mercury, Sulphur, and Iodine, have been detected chemically in

it. It has happened, when a course of Mercury has followed the

administration of Sulphur, that parts of the skin have turned black,

from the formation of Sulphuret of Mercury. So it is proved of many of

these Diaphoretics, and thus rendered highly probable of the rest, that

they are true Eliminatives, being themselves excreted by the glands

which they excite to action.

When copious diaphoresis has been excited, care should be taken that it

be allowed to subside gradually, or the consequences may be hurtful. It

may be remarked that cleanliness of the surface, by which the

sudoriferous ducts are kept open and healthy, is highly important to the

proper function of the skin.

Diaphoretics are useful in various disorders. In what is called _a

cold_, when the function of the skin has been suddenly interfered with,

and the vaporous transpiration is all thrown upon the lungs, producing

irritation or inflammation of the respiratory mucous surface,

Diaphoretics are generally required. In Fevers, and some other

disorders, as Gout and Rheumatism, which are apt to improve or to pass

off with an increase of perspiration, and in which it often seems likely

that some morbid material may be eliminated by this channel, the same

medicines are constantly necessary. When another secretion is unduly

copious, an increase in the sweat may cause it to diminish. Thus in some

cases of diarrh[oe]a, and still more in diabetes, Diaphoretics are

appropriate. In contrary conditions, as when the formation of urine is

unnaturally small, on account of granular degeneration of the kidney, it

is again important to stimulate the secretion of the skin, that it may,

if possible, be able to replace the other. (_Vide_ p. 280.)

ORD. VI. DIURETICS.

These are medicines which tend to increase the secretion of urine.

By means of the kidneys a large amount of aqueous material is every day

separated from the blood, and excreted. This water is in the first

instance absorbed by the surface of the stomach and intestine. The

causes which demand its excretion are twofold. In the first place, it is

necessary that the blood should be kept down to its normal standard as

regards water, and that the surplus fluid which is daily added to it

should be removed. Secondly, this water is required in the urine as a

vehicle, to hold in solution there certain soluble matters which are

continually forming in the blood, or being received into it, but which

have to be excreted from it by means of the kidneys. These matters

comprehend a variety of salts,--and a number of nitrogenous substances,

of which the best-known are urea and uric acid. These last are formed in

the blood by the gradual decomposition or change of the animal tissues

through which it flows. When retained in the circulation, on account of

a failure of the function of the kidneys, they act as poisons.

The kidneys are the chief emunctories of water; and mineral substances

which are soluble in water tend for this reason to pass out into the

urine. Many of these, as the salts of Iron, Silver, Lead, and Copper,

are Astringents, and tend to diminish rather than to increase the amount

of urine. But the urine is so necessary and so constant a secretion,

that it is very difficult to diminish it in quantity. Saline medicines

act as Diuretics under certain conditions. So also do acids and

alkalies, and many vegetable substances, which will be presently spoken

of.

The soluble substances which thus pass off in the urine, and act as

Diuretics, are many in number, but they are all uncertain in action, for

several reasons. The amount of the urine depends very much on the

quantity of water taken into the stomach, or absorbed from the

atmosphere through the skin; so that when there is not a sufficient

quantity of water in the system, it is impossible for more urine to be

formed. This necessary absorption of water depends again upon the

pressure of the circulation; when this is too great, it cannot go on,

and the urine is diminished. A large increase in any other of the

secretions, as that of the bowels,--but particularly of the skin, as in

warm dry weather,--hinders diuresis. The secretion of the urine is

favoured by those conditions which repress the perspiration; as by

coldness of the surface, light clothing, a cold and damp condition of

the atmosphere, and the erect posture. In the fourth place, the urine is

diminished by causes which impede the circulation, as by congestion of

the kidney or liver,--or of the whole venous system, on account of

obstruction in the heart,--conditions which produce dropsy.

Those medicines act as indirect Diuretics, which, by favouring the

removal of one of these hindering causes, tend to allow the secretion of

urine to go on as in health. The powerful action of the heart in fevers

and inflammations causes such a pressure on the vessels as to retard

absorption, and thus hinders diuresis. A hard bounding pulse and hot

skin favour sweating more than diuresis, though they often diminish both

of these secretions. Both are assisted by a relaxed state of the

circulation, which favours the absorption of fluids. Thus venesection,

purging, Antimony, or any thing that diminishes a febrile reaction, will

help diuresis in such cases. In cases of congestion on account of

cardiac disease, Digitalis, which, by powerfully weakening the force of

the heart, both diminishes congestion and favours absorption, is a most

efficient promoter of the natural function of the kidneys. When the

portal circulation is the seat of the obstruction, a mercurial, such as

blue pill, which especially acts on the liver, will be a most desirable

adjunct to the other remedies employed. Tobacco and Lobelia, like

Digitalis, promote diuresis by diminishing the force of the heart.

_True Diuretics._--Though all true Diuretics pass into the urine, the

converse of this, _i.e._ that all matters which pass into the urine are

Diuretic, is not always true. Thus the astringent mineral salts pass

frequently out of the system in the urine, but seldom affect its amount

in either way. And for the reasons already enumerated, it is often

impossible, even by the most powerful medicines of this order, to

increase the urine beyond a certain amount.

Diuretics may be somewhat loosely arranged in four groups:--1. Water,

and soluble mineral substances, _i.e._ acids, alkalies, and salines

under certain conditions; 2. Acrid matters of various kinds; 3.

Alcoholic and ethereal liquids; 4. The minerals which increase all

secretions.

Diluents promote the secretions of the skin and kidneys. A certain

quantity of water must be given with every diuretic dose, and the larger

the quantity the greater will be the effect produced. In the case of a

Diaphoretic, this is all that is required. But as Diuretics are

generally given, as in dropsies, for the purpose of eliminating fluid

out of the system, this object would be clearly defeated by the

introduction of a large quantity of water into the system. This,

therefore, should be avoided. The free acids, both mineral and

vegetable, with the exception of Sulphuric acid (_vide_ p. 262,) pass

into the urine, and act as Diuretics. So also do the mineral alkalies.

But as these medicines have important agencies in the blood, and tend

further, by altering the reaction of the urine, to produce in it

deposits of different kinds (_vide_ p. 151,) they can seldom be safely

employed for this purpose. Salines are more appropriate. They should not

be given in large doses, for they will then act upon the bowels. The

dose should be small, and moderately diluted with water. To prevent it

from acting upon the skin, the conditions which favour diaphoresis

should be, if possible, avoided. The subject of the action of saline

medicines, and the effect of dilution upon this action, has been already

considered. (p. 74.)

The acrid Diuretics are perhaps the most powerful medicines in the

order. One of them, Cantharides, is an animal product. Some contain or

consist of volatile oils: as Juniper, Turpentine, Cajeput, Copaiba,

Horseradish. These volatile oils may act upon the skin instead of the

kidneys, under the conditions which are mentioned above as favouring

diaphoresis. Others of this group contain peculiar vegetable principles;

as Broom, Chimaphila, Taraxacum, Colchicum, and Squill.

Alcohol, Ether, and Nitric ether, act powerfully both on the kidneys and

on the skin. Wine, which further contains certain volatile oils, and

sometimes a vegetable acid, acts on the kidneys when drunk in any

quantity. The diuretic effect of these liquids is, as in the case of

salines, greater when the surface is cold, and less when it is warm and

covered.

Mercury, Antimony, and Iodine, which increase more or less all the

animal secretions, act, among others, upon the secretion of urine.

Iodine particularly is said to be diuretic. Mercury and Antimony are

most efficacious as indirect agents; the former by stimulating the

function of the liver when impaired, the other by diminishing the

pressure on the vessels in febrile cases.

A large number of Diuretics are themselves secreted by the kidneys, and

have been proved to pass out into the urine. A great many have been

detected in the urine by different chemists, especially by M. Wöhler.

The Carbonate, Nitrate, and Chlorate of Potash, and the Iodide of

Potassium, have been found there. So also have the mineral acids--the

vegetable acids--Magnesia--Mercury,[46] in combination--and Iodine, in

the form of Hydriotic acid. Among vegetables, the principles of

Chimaphila and Uvæ Ursi--the oils of Turpentine and Juniper, somewhat

altered in nature--the oil and resin of Copaiba--and the acrid principle

of Cubebs, all pass into it. Other substances, which are not diuretic,

but astringent, have been found in the urine; as Alum, Lead, and the

Morphia and Meconic acid of Opium.

When a powerful Diuretic is given in too large a dose, it may cause a

degree of action sufficient to produce congestion of the kidney, and so

defeat the object for which it was intended. For congestion of a gland

is invariably followed by a diminution or stoppage of its secretion. So

a large dose of Turpentine or Cantharides may cause a dangerous attack

of strangury, or even a total suppression of the urine for a time.

(_Vide_ p. 274.)

It can hardly be said that Diuretics are of very extensive application

in the treatment of disease, or that they are medicines which can ever

be much relied upon. For not only are the remedies themselves uncertain

in action, but it happens also that the disorders in which they are most

required are of a peculiarly obstinate nature.

There are two chief actions for which Diuretics may be required. They

may be used: (1.) to eliminate solid materials from the blood; (2.) to

promote absorption, by diminishing the amount of fluid in the blood. It

is easier to employ the first than to exert the second of these

operations.

When there is habitually a deposit in the urine, of lithates, or

phosphates, or other solid matters, the simplest mode of obtaining a

solution of this deposit, and thus preventing dangerous consequences, is

to increase the amount of the fluid part of the secretion. Water is the

best medicine for this purpose, and all Diuretics that are given with

such an object should be freely diluted with water. In Gout and

Rheumatism, remedies of this order may be of service by promoting the

excretion from the blood of the uric or lactic acid formed there. They

may also be used as Eliminatives in fevers and other disorders. In the

strangury which may sometimes follow the application of a blister to the

skin, copious draughts of water are often prescribed with advantage, for

they serve to wash out of the blood the acrid matter which has been

absorbed from the surface.

It is for the second purpose, in cases of dropsy, produced by congestion

of the liver, kidneys, or general circulation, that Diuretics are most

urgently required, but are least efficacious. This congestion or

pressure on the veins diminishes the amount of the secretion of urine,

and by so doing increases itself, and aggravates the effusion and

disorder. The same cause most effectually hinders the action of a

Diuretic. If only we could largely increase the secretion of urine, the

pressure on the venous system would be diminished, and absorption of the

effused fluids might take place. In some cases of dropsy caused by renal

congestion, the attempt is so hopeless that it is better to resort to

Diaphoretics. In obstruction on account of heart disease, or congestion

of the liver, we may sometimes gain our point by combining other

Diuretics with Digitalis or Blue-pill, remedies which tend to remove the

causes by which the diuretic action is hindered. (_Vide_ p. 304.) Even

then we can often produce a much more copious and effectual drain of

fluid from the blood by an action on the bowels, as by a dose of Jalap

or Elaterium. When a Diuretic is required to eliminate fluid from the

system, the dose should not be much diluted with water; this should only

be done when we desire to eliminate solids from the blood. It is often

advisable to combine together a number of different Diuretics, in the

same prescription, so that by their joint but various agencies the

causes which hinder their action may be overcome. The operation of

Diaphoretics is opposed to that of Diuretics, but it is not always so

with purgative medicines. The urine is often increased by the action of

a hydragogue Cathartic; and a combination of Blue-pill and Squill

supplies us with one of the best of known Diuretics. It is applicable in

cardiac dropsy as well as in hepatic cases.

Thus is concluded a brief outline of the actions and uses of the six

orders of Eliminative medicines.

CHAPTER IV.

ON THE ACTION OF SOME OF THE MORE IMPORTANT MEDICINES IN PARTICULAR.

The chief objects for which I have designed this Fourth Chapter are that

I may be enabled to illustrate some general principles of the action of

medicines which have been laid down in the Propositions, and show in

what manner they are applicable to special cases,--and to enter into

certain details respecting the more important remedies, which have not

been attempted as yet. Of many of these medicines a tolerably full

account has already been given; but they may again be mentioned here for

the purpose of shortly summing up their several actions, and comparing

them one with another.

It often happens that there is more than one point of view from which

the action of a medicine may be regarded. For many medicines are

numbered under several distinct heads, being included in different

groups on account of the several phases of their operation. There are

three stages in the progress of the remedy through the system, at each

of which it may exert a special action. There is a contact with the

surface; a continuance in the system; and a passage out of the system.

In the first place a medicine touches the mucous surface of the

alimentary canal; here some few evidence their action. From this, if in

any way soluble, it passes into the blood. Here it may act on the blood,

being Hæmatic. Or it may employ the blood merely as a means of transit,

and direct itself towards nerve or muscular fibre, being Neurotic or

Astringent. But we have seen that none of these medicines, with the only

exception of Restorative Hæmatics, can remain long in the system. They

must pass out, and the mode of passage is through the glands. Here is a

third opportunity of operation. The medicine may act now as an

Eliminative, increasing the secretion of the gland; or, more rarely, as

a glandular Astringent, because tending to diminish it.

As a general rule, though not in all cases, the most important action of

a medicine is that which it first evidences, the subsequent operations

being secondary, and of less moment. Thus Mercury is, in the first

place, a Catalytic Hæmatic; in the second place, an Eliminative.

Creosote is firstly a general Sedative, secondly an Astringent. Antimony

probably belongs to three out of the four classes, and its second

operation is perhaps the most important. It is a Catalytic, a special

Sedative, and also an Eliminative.

COD-LIVER OIL.

Class I. Div. I. Ord. I. ALIMENTA.

This oil has been proved by the experience of many physicians to be a

medicine of great utility in most cases in which there is a general

deficiency of fat in the system. It is thought also to exert a specific

action in the cure of pulmonary Phthisis, and it certainly appears to be

the only medicine that possesses any marked or peculiar power over the

progress of this disorder. When administered in favourable cases it

seems not only to have the power of fattening the patient, but to be

able also to combat and cure the disease itself, arresting or retarding

the tubercular deposit. Sometimes it is unable to do this; but in all

cases of consumption a trial should at least be given to it. It is of

most service when the disease is only incipient, and, if given in the

first stage, may often prevent its further progress; but it may even

cure patients in whom the deposit has passed the stage of softening, as

appears from the reports of the Brompton Hospital.

It is also of use in Scrofula, in chronic Rheumatism, and in cases of

emaciation generally. It may prove nutritive in Diabetes mellitus,

because it is not likely to be converted into sugar in the system,

whereas in that disorder all kinds of food, excepting fats and oils, are

liable to this change. Cod-liver oil is assimilated to the tissues, and

there seems to be something in it which not only renders it more easy to

assimilate than other oils, but which further endows it with a special

influence over tuberculous diseases. It does not appear that any other

oils are equally effective. Though Dr. Duncan and Mr. Nunn have

recommended Almond-oil instead of Cod-liver oil, yet the general

experience of others is decidedly against such a substitution.

It has not yet been clearly ascertained to which of the constituents of

this oil its valuable properties are owing. Being itself an animal

product, it is for that reason more easy of assimilation than a

vegetable oil. Many have attributed its virtues to Iodine, of which,

according to De Jongh, it contains 29 parts in 100,000.

Dr. Theophilus Thompson has tried both Olive and Almond oils in

consumptive cases, but has not found that any material benefit is

derived from their use. He considers that Cod-oil produces its best

effects in cases where Iodine would be inadmissible. Neither does he

think its virtue to be due to the biliary matters which it contains, for

a mixture of ox-gall with Almond-oil does not supply its place. Cod-oil

contains 7-1/2 parts in 100,000 of Phosphorus. Dr. Thompson supposes

that its efficacy may be partly owing to this. He has made trial of

Phosphuretted Almond-oil, containing one grain of Phosphorus to the

pint. He suggests that this Phosphorus may be of use in diverting some

of the Oxygen from the tissues. This is to adopt Liebig's theory of the

excess of Oxygen in Phthisis; an idea which is not very consistent with

the experiments of Dr. Hutchinson on his Spirometer, from which it

appears that the quantity of air inhaled at each breath by a consumptive

patient is considerably less than in health, on account of a diminished

capacity of the lungs. But when a continual fever has set in, an

oxidation and waste of the tissues must certainly take place. (_Lancet_,

October, 1851.)

The Phosphorus in Cod-liver oil would soon be oxidized, and it would

seem to be too small in amount to be of service in this way. If any

thing were thus needed as a pabulum for Oxygen, we might suppose it to

be the oil itself that was thus burnt.

Possibly the utility of this medicine may depend upon a combination of

several constituents and various properties. It is an oil; and thus of

use as an Aliment, and as a supporter of the respiratory function. It is

an animal oil; and thus peculiarly adapted for being digested, absorbed

and assimilated to the adipose tissues of the human body. It contains

Iodine and Bromine, which are useful as Alteratives or blood medicines,

both in Phthisis and Scrofula. Their proportion will not seem so small

when the large dose of the oil and its frequent repetition are taken

into account. But their presence alone would not be sufficient to

explain the utility of the oil. It contains also Phosphorus, a general

Stimulant, which may prove of use when there is a failure of the nervous

forces.

Sometimes the dose of the oil excites a most distressing nausea. This

may perhaps be prevented by a judicious modification of the vehicle. It

may be floated on an aromatic water, on a bitter infusion, on milk, on

wine, or on cold tea, to suit various tastes. In other instances the

dose is swallowed without inconvenience, but the patient is not

fattened, nor is his condition in the least improved by it. In such

incurable conditions it is probable that there is often an organic

disease of the Pancreas, or a failure in the function of that gland. For

it appears that the absorption of fats is effected by means of an alkali

contained in the Pancreatic fluid. When there is reason to suspect this

cause of the emaciation, it is advisable to saponify the oil by shaking

it with a sufficient quantity of solution of Potash or of Carbonate of

Soda. The dose will then be in a state of solution, and ready for

absorption.

Cod-liver oil may be used with advantage as a vehicle for Iodide of

Iron, in scrofulous cases. Two grains of this may be dissolved in each

ounce of the oil. (_Vide_ pp. 119, 191, 229.[47])

SULPHURIC ACID.

Class I. Div. I. Ord. II. ACIDA.

Class III. Ord. I. ASTRINGENTIA MINERALIA.

This medicine acts chemically as an acid in the blood and in the

secretions. When diluted it is easily absorbed, and meeting in the

stomach with an acid secretion, it passes into the circulation without

being first neutralized. If in small quantity, it is neutralized by the

slight excess of alkali in the blood; if in larger amount, it may exceed

this alkali, and displace and set free other acids in the blood,

combining with their bases on account of its strong affinities. In all

cases it increases the quantity of free acid in the system, and tends to

render the secretions, as the urine, more acid than they were before.

(_Vide_ Dr. Bence Jones's _Animal Chemistry_, p. 49.)

By this chemical action Sulphuric Acid is rendered useful in alkalinity

of the blood, which may occur in fevers; or of the urine, as in

Phosphaturia. It thus acts as a Restorative Hæmatic. But it is not right

that there should be more than a certain quantity of this acid in the

system. So that when introduced in large quantity it must be excreted.

It does not appear that it is itself excreted in the urine, though it

may cause an excess of other acids in that secretion. On this point Dr.

Bence Jones has made some careful experiments. (_Anim. Chem._, p. 75.)

He finds that Sulphuric Acid does not pass off in the urine, either free

or in combination, except when given in great quantity. Now it is found

that Sulphuric Acid is of great use as an Astringent in diarrh[oe]a.

Placing these two facts in juxtaposition, it would seem that the acid,

which is doubtless absorbed in the first place, must afterwards be

eliminated from the system by the surface of the bowels. This is perhaps

because the secretion of this mucous membrane is the one which is least

likely to be deranged by the presence of the acid.

The free acid is an Astringent, and has the power of coagulating

albumen, and causing the contraction of muscular fibre. (p. 256.) Though

probably neutralized and combined while in the blood, it is free before

absorption, and after excretion. Before absorption it is an Astringent

to the surface of the stomach; after and during excretion, to the

surface of the bowels. It is useful chemically in alkaline Pyrosis. Its

astringent property explains its utility in _acid_ dyspepsia, which

appears at first sight incomprehensible. Lactic acid, or some similar

acid, is poured out in excess by the glands of the stomach. Sulphuric

acid topically constringes the muscular fibre of the ducts of these

glands, and in this way diminishes their secretion.

The acid, if in excess in the blood, may tend to brace the system by

causing a general contraction of the fibres of the voluntary muscles.

But it is chiefly on account of its anti-dyspeptic agency, and its

astringent action on the secretions, that the title of Tonic has been so

often applied to it.

Next to that of the bowels, the acid appears to act most on the

secretion of the skin. Probably there also eliminated in a free state,

it is thus able to diminish excessive diaphoresis.

It is applicable in cases of Hæmorrhage, when this takes place from a

mucous membrane, for it probably passes off in small quantities from all

the mucous surfaces. It is very useful in diarrh[oe]a. (_Vide_ p. 294.)

Being a special Astringent to the intestinal mucous surface, it may

possibly be useful even in malignant cholera, especially if given in the

early stage of that disorder. (_Vide_ pp. 120, 154, 262.)

POTASH.

Class I. Div. I. Ord. III. ALKALIA.

Class I. Div. II. Ord. I. ANTIPHLOGISTICA.

Class I. Div. II. Ord. III. ANTISCROFULOSA.

Class IV. Ord. VI. DIURETICA.

Potash is one of those medicines which have several distinct actions;

but its various operations are comparatively simple in nature, and easy

to comprehend. In the solid state it is powerfully caustic and

corrosive, having a great affinity for water, and abstracting it from

the animal tissues with which it is brought in contact.

When a dose of the solution, properly diluted with water, is

administered internally, it passes first into the stomach, and either

combines with the acid of the gastric juice, or, what is more probable,

it becomes absorbed too rapidly to be neutralized by it. It passes then

into the blood, and probably exists in that liquid in a free state, for

the blood already contains a slight excess of alkali. However this may

be, it certainly increases the amount of alkali in the system.

Its hæmatic action depends in great part on its power of neutralizing

acidity. It is thus useful in cases of acid dyspepsia, heartburn, or

gastrodynia, when it combines with the excess of acid which exists in

the gastric secretion, and probably also in the blood. For the same

reason it is useful in some cutaneous diseases that are connected with

disordered digestion. It is employed in Gout and Rheumatism, where there

is obviously an excess of acid both in the blood and in the secretions.

(p. 202.)

When Potash, is administered in any quantity, it must be excreted from

the blood. The secretion of alkalies is mainly performed by the kidneys,

and by their agency we may render the urine neutral or alkaline, and

thus counteract a tendency to lithic deposits. (_Vide_ Solvents.) For

this purpose Potash is preferable to free Soda, for the lithate of Soda

is comparatively an insoluble salt.

The salts of Potash with vegetable acids change into carbonates while in

the blood, and will render the urine alkaline. M. Wöhler, who has

discovered this fact, finds that it does not occur with the super-salts.

Even the neutral salts escape the oxidation when they are given in such

large doses as to act on the bowels.

Potash is thus a Restorative Hæmatic, and where, from any reason,

alkaline matter is needed in the system, it directly supplies the want.

But it has also other actions which render it Catalytic, and which are

evidenced in disorders in which there is no such deficiency of alkali.

By dissolving Fibrine, it tends to prevent its deposition from the

blood. It thus interferes with the inflammatory process, and acts as a

general Antiphlogistic. It is possibly by a similar action that it seems

able to counteract the deposit of crude tubercle, and exerts a special

action in the prevention and cure of strumous disorders. It is very

useful in the early stage of Phthisis, and in all stages of Scrofula. In

Syphilis, when occurring in scrofulous subjects, Potash has sometimes

been used with greater advantage than Mercury.

Potash and its salts have been used in Scurvy by Dr. Garrod, on the

supposition that there is in that disorder a particular deficiency of

Potash in the system. But the fact that Citric acid is at least of equal

utility in the treatment of scorbutic diseases, would seem to be opposed

to such an idea. When given in moderate doses, and not retained in the

system, Potash and its salts pass out into the urine, and act as

Diuretics. (_Vide_ pp. 126, 187, 193, 202, 206.)

QUININE.

Class I. Div. I. Ord. IV. TONICA.

Though the utility of this important remedy is often of a sufficiently

direct and obvious character, its precise mode of action is enveloped in

no small degree of doubt and obscurity. This subject has been discussed

at some length in the article on Tonics.

It appears, from the character and results of its medicinal influence,

that it is exerted primarily in the blood, and not on the nerves. It is

included in the Restorative group of Hæmatics, and the general results

of its action differ widely from those of a Catalytic Hæmatic. It

produces no marked effect upon the system in health. Its operation

consists in the cure of general debility, however produced, and in the

prevention of periodic disorders in the blood. Debility depends on a

want in the blood, and not on any active morbid process; and there are

circumstances which render it likely that Ague may be curable by the

supply of a similar want.

Quinine is also serviceable in Gout, Scrofula, Dyspepsia, and other

disorders; in all of which other medicines, which stimulate the

secretion of the bile, are more or less applicable. Torpidity of the

liver is likewise a usual accompaniment of the various forms of

debility, and occurs in intermittent, remittent, typhoid, and yellow

fevers; in each of which this medicine has been recommended, and used

with advantage. In fact it may be said, that in all diseases in which

Quinine is used there is a failure in the secretion of bile; and in all

diseases in which there is a failure in the secretion of bile, Quinine

is serviceable.