PATH 
theirabforption, and local application to the circulating 
powers. This remark will likewife apply to many of the 
Sedatives ; for, though thefe latter fubftances are for 
the moll part abforbed and carried into the circulation, 
and thus operate immediately on the contradfile powers 
of veffels, others exift of which the inftantaneous adtion 
allows of no explanation except the fuppofition that they 
adt on the nervous fyftem through the medium of the 
ftomach. It is obvious however, that, ftridtly fpeaking, 
all medicines adting on the nervous fyftem fliould be 
comprehended in another divifion ; but, as we before 
obferved, the modus operandi of the refpedlive articles in 
the materia medica is not fufficiently eftablifned to allow 
us to arrange them thus clofely according to their effedfs. 
We muft obferve, in this place, that many ftimulants 
attended with difcharges mayindiredlly produce fedative 
effedts by removing plethora ; as purgatives, diuretics, 
&c. The eftablifliment of the oppofite fadf, viz. that 
fome fubftances produce diredly fedative effedts, is a 
grand feature in the new Italian dodtrine, and in which 
that dodtrine is oppofed to the Brtinonian theory, which, 
as we have before fhown, fuppofed that all medicines 
were ftimulants, and only produced debility by promoting 
difcharges. This opinion is not to be difmifl'ed with 
quite fo little ceremony as many parts of Brown’s doc¬ 
trines ; for, though not admiftible to its full extent, it is 
rational to conjecture that many fubftances do produce 
inadlion of particular parts or organs by exceflive ftimulus 
on others, and thus that the clafs of diredt fedatives is 
very limited indeed. 
The moft powerful fedative agent that we ufe in me¬ 
dicine is Bleeding. This operation is however fcarcely 
capable of being arranged under any divifion ; for, in the 
firft place, if the fyftem is gorged with blood, there can 
be no doubt that fuch a ftate may arife as will preclude 
the rapid adtion of the heart; and in this cafe, by dimi- 
niftiing the quantity of blood to be moved, the motive 
power remaining the fame, the velocity will neceflarily 
be increafed. Thus, bleeding is a Jlimulant, on the other 
hand the rapidity of the heart’s adlion is in certain 
ftates reduced, or rendered flower, by bleeding. Thus, it 
is a fedative. Again, fyncopemay be induced by bleeding; 
and, as this is dependent on diminiftied circulation 
through the brain, the operation here holds relation 
with the nervous fenfibility. And further, the emptinefs 
of the fanguineous fyftem produces increafed adtion in 
the ubforptive powers. 
According, then, to the various ftates of difeafe, this 
operation produces different effedls, which are ftill further 
varied by the time and manner of its performance. With 
regard to the time, this has great influence on the cura¬ 
tive refults. Thus in inflammations of all kinds, it i3 
necefl’ary to bleed in the early ftages, left the continuance 
of that difeafe fhould terminate in change of ftrudlure, or 
at lead in permanent dilatation of veffels. The manner of 
bleeding refpedts the abftradtion of blood from fmall or 
large orifices, by frequently-repeated and fmall, or by 
large and fudden, evacuations. Topical bleeding is ano¬ 
ther mode of abftradling blood which is ufefully employed 
in a great number of inflamed or excited parts, when 
previous exhauftion or other caufes preclude general 
bleeding. With regard to the mode of performing ve- 
nefeCtion, arteriotomy, acupunCture, &c. fee the article 
Surgery. 
The a£tion of the abforptive fyftem is increafed with a 
view to the removal of many folid depofitions, fluid fe- 
cretions, and extraneous bodies, &c. Like the circula¬ 
tory fyftem, it may have its contradlile phenomena in¬ 
creafed or diminiflied. The firft indication is attempted 
by mechanical preflure, and by certain medicines called 
ftimulants ; and it feems further increafed in direft pro¬ 
portion to the exhaufted ftate of the heart and arteries. 
The fecond change, or the diminution of the aCHvity of 
s^fpEbents, is not found to attend with certainty the ex 
hibition of particular drugs; but it is produced by various 
Vol. XIX. No. 1290. 
O L O G Y. v 09 
morbid alterations, by heat, by the defeft of mechanical 
preflure, and by the reduction of nervous fenfibility. 
To return however to the ufe of ftimulants ; mechanical 
prejfure is an agent which exerts great and general in¬ 
fluence over the abforbent fyftem. In their courfe 
through the extremities of the body, the abforbents are 
compreffed by the diftenfion of the arteries, and during 
the contraction of mufcles ; within the cavities of the 
abdomen and thorax, they are fubjeCted to the preflure 
of the ingefta, of the diftended air-cells of the lungs, the 
movements of the diaphragm, and of the refpiratory and 
abdominal mufcles. Atmofpherical preflure, as well as 
the weight of clothes, &c. is likewife to be taken into 
eftimation. It is obvious that, as abforbents are furnifhed 
with valves which prevent the return of fluids towards 
their open mouths, prejfure muft accelerate the flow of 
their contents towards their venous terminations, 
It muft here be remarked, that the effeCt of long-con¬ 
tinued preflure is probably two-fold; operating on the 
one hand to increafe abforption, on the other to prevent 
depofition. Medicines which increafe abforption operate 
for the moft part by increafing contraction. But they 
may further, in fome ipftances, render folid depofi¬ 
tions lefs difficult of abforption, by producing folu- 
tion of their conftituent parts. That an empty ftate of 
the fanguineous fyftem generally renders abforption 
more aCtive, is a faCt which we fliould be inclined to ad¬ 
mit a priori; and it has received full confirmation from 
the well-known experiments of Majendie. It explains 
how purgatives, diuretics, &c. to which the older phyfi- 
cians attributed abforptive powers, may really bring on 
abforption, by caufing depletion ; and it further renders 
plain the circumftance, that a great number of medicines 
do not manifeft their falutary operation except in ex¬ 
haufted depleted patients. 
In our therapeutical indications, one of the moft im¬ 
portant is the imitation of'nature in the production of 
oppofite difeafes. That difeafe in one part or ftruCture 
of the body often ceafes on its production in another, is, 
as we have before ftiown, a general law in pathology, fub- 
jeCt however to many exceptions. It is in expectation of 
producing this falutary change that we ufe many of the 
moft powerful ftimulants. Thus blifters, muftard-cata- 
plafms, embrocations, moxa, &c. are employed with the 
intention of converting difeafes, i. e. of inducing aCtion 
in a part not effential to life, for the purpofeof removing 
it from one in which its direefteCts are known and appa¬ 
rent. It is to be obferved, however, that contra-irrita¬ 
tion is a mean which can only be reforted to with ad¬ 
vantage in certain degrees of inflammation ; for it is 
known that, in inflammations of the higheft magnitude, 
blifters, when applied before bleeding and evacuants have 
been premifed, increafe general irritation without alle¬ 
viating topical difturbance ; and this holds good in re¬ 
gard to moft other fubftances of the fame clals. 
As appendices to the ufual and common remedies, we 
have to mention medical eleCfricity, and the inhalation 
of gazeous fluids. Each of them has received an ephe¬ 
meral and exceflive degree of praife ; and hence, like 
many of the furprifing remedies perpetually arifing, have 
fallen into undeferved contempt. 
The cure of the moft violent and inveterate difeafes 
has been afcribed to eledricity, All that now remains 
certain with regard to it is, that it is a powerful ftimu- 
lant, and one which is the more ftrongly recommended, 
becaufe it can be applied to a variety of parts, when the 
common methods of ftimulation cannot be employed. 
The mildeft modes of ufing electricity are thofe rnoli in 
vogue at prefent, as its violent application is reprobated 
by the belt practical writers. Its ufe in fufpended ani¬ 
mation, in chronic glandular enlargements, in atony of 
the organs of generation, are well known. 
Animal electricity, or Gaivanifm, is in fome refpeCts 
fimilar to common eleCtricitt n its effects, and in others 
different; but, in a medical view, it has not anfwered the 
D d expectations 
