Robert Hooper.

A new medical dictionary, containing an explanation of the terms in anatomy, physiology ... and the various branches of natural philosophy connected with medicine online

. (page 18 of 177)
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Atbtci. Small sinuses in the rectum*
which do npt reach so&r up as to pesfo-
rate into its cavity.

ATRIPLfiX FCETroA. Atripiex •lido,
l^ttoana. Gar9mimm, Baphexm Ch^tnH"
fodtumfifMitn. BHtumfmHditm. •tink-
mg orach. The very mitd smell of this
plant, Chenop9dhtmvuhariat f^&a inU'
gmrrSmU rhombeo'-voatU, JUri6u9 eengkme'
rwtU axUaribu9t of Linnaeus, induced phy-
sicians to exhibit it in hysterteal diseases.
It is now superseded by more active prepa-
rations.

Atr'ipliz BoarBBSis. The systematic
mmie for the a»iplex %ativa of the pharma-
copoeias. See Mriplex tativa.

AmmxK SATivA, The herb and seed
of this plant, .4<f^a; hertemeU caule ereeU
kerbaeeo, foiit tnatupdaribtUt of Linnaeut,
lunre baen eihibhed medicinaUv as anti-
scorbutics, but the praetioe of the pre-
sent fiay appears to have totally Kjeeted
them.

ATBOPA. XrnmAnft9^\he^deA9
otDestiny ; sO caHed feom its Iktal^flbets.)
The deaffly night-shade.

Tbe name ot a genus of plants iu the
linniean ^stem. Claes, PerUamdritu Or*
der, MomogynU.

Atbopa BBiaawnnrA. The systenuoic
name for the 'belladonna of tbe pharmac^
poeias. See BeUt^nma. '

Atbopa XAjniBAi^Ba. Ttie systematic
name for the ^«it i^uch afibrds the rrndkc
moHdagot^ of tbe pbarmacqpeeias. See

ATEOKillA. 8ee4lrf^y.

ATSOPIfr. ^nra -m neg. and t^k^ to
nomish.) Atraplda, MmnmmtM, Nerfous
censMnptioo. This disease is marked by
a gradual wasting of the body, unaccompa-
nied either by a difficulty of breathhig,
cough, or any evident forer, but usually
attended wkh a loss of appeti^ and iai-
pjured iligeslioik It is arranged by CuUn



in tbe cfan cachexia^ and order macnre$.
There are four species : —

1. When it takes place fh>m too copious
evacuations, it is termed atrophia inanitO'
rum s by others called tabet nutricum f — 90-
datoria /— ^ oanguijhixu, &c.

% When l^m famine, atrophia fameUfi^
rxim,

3. When from corrupted «itrim«nt,a#rs-
phia eacochymica,

4. And when from an interruplioQ in the
digestive organs, atrophia dtbiUum,

The atrophy of children, is called palda*
tropia. The causae which commonly gite
rise to atrophy, ave a poor diet, unwhole-
some aift, excess in venery, fluor albus, se-
vere evacuations, continulni^ to give atiek
too long, a free use of spmtuous liciuois,
mental uneasiness, and worms ; but it fft*
quently comas on without any evident
cause. Along wilh the loss nf apatite and
impaired digestion, there is a dimimition of
atrength, the fisbce is pale and Moated, the
natural heat of the body is ^mewhat di-
miniahed, and the lower extremities are
cadematous. Atroohy, ariae from whatever
cause it mmr, is usumly very difficult to cure,
and not unfrequently terminates in dropsy.

ATT^NUANTS. {Attemuantia, sc medi-
eamentai from attemWf to make thin.)
Diluents. Those substances ate so termed,
which possess a ixywer of imparting to
the blood a more thin and more duid con-
sistence than it had previous to their exhi*
bition ; sush are, mgua, $erwm kutis^ dec.

ATTOUL£N8 AUQ»M. (Attoikno ,
from atttti», to lift tip.) AtfUent awicuUt
of Alhinus and Douglas ; Superior aurio of
Winslow, and AMiene awriculam of Cov-
per. A common muscle of the ear, vhicli
arises, thin, broad, and teivdinous, fiom the
tendon of the occipito-frontalis, from which
it is almost inseparable, whftre it covers tbe
aponenroiis of the temporal im^scle ; aiif
is mserted in^o the upper pan of the ear,
opposite to the ant^etix. Its usft is to
draw the ear upwards^ and to tnake the
parts into which it is inserted, tense.

AraoLmuM ocuii. One of the seeti-mus-
dku which lie upon the upper part of the
globe and pulls up tbe eye.

Attovitvs MOBBtrs. (From attono, to
sitfprise $ so called because the person falls
down suddenly,) AtUmittu ohtpor. The
apoplexy aiide|)i)epsy.

ATTHACTION. (From attraho^ to at-
tract. Affinity.)

The terms attraction, or affinity, and re^
pnlsion^ in the Uniguage of modjsm phi-
losophers, are employed merely as the
exjlresiton of the fi^neral facts, that
tlie masses or particles of matter have
a tcndflQcy to approach to, or to recede
from one another, and to unite to, or re-
pel each other, under certain ctrcuaKtAiH
ce»



Digitized by LjOOQIC



^



ATTRACTION.



All bodies ha\'e a teudeocy or power to
attract eac^ other more or leas, and it is
this power which is called attraction.

Attraction is mutual, it extends to inde^
finite distances. All bodies whatever, as
well as their component elementary par-
tielei, are endued with it It is not annihi-
Islted, at how great a distance soever we
suppose them to be plsced from each
other; ^ettlier does it disappear though they
be arranged ever so near each other.

The nature of this reciprocal attraction,
or at least the cause whicn produees it, is
altogether unknown to us. Whether it be
inherent in aU matter, or whether it be the
consequence of some other agsnt, are
Questions beyond the reach of human un«
^ratsnding; but its eiistence is nerertbe*
less certain.

Proqfl ofattraetkn.

That the power of attraction rrally exists
la obvious from the slightest view of the
phenomena of nature. It,is proved with
mathematical certainty that the eclestia).
bodies, which constitute the solar system,
are urged towards each otlier by a foroe
which preserves them in their orbits. It
is further proved beyond any doubt, that
this plsnetary attraction is possessed not
only by the heavenly bodies as wholes,
but that it also extends to the smaller par-
ticles t>f which they are formed, as may be
evhiced by means of the following experi-
ment!.

/Vr#«.-»If we place two or more globules
of mercury on a dry glass or esrth^ plate,
and push them gently towsrds each other,
the globules will attract each other,
and rorm one mass or sphere greater in
bulk but precisely the same in nature.

Sevndlsi-^U 9. i>kite of clean glass, per-
fectly diy, be lud on a large globule of
mercuiy, the globule, notwithstanding the
pressure applied to it, continues to preserve
its spherical form ; if we p^raduaUy charge
the plate with weiglifs carefully, the glo-
bule will be depressed and become thinner
and thinner ; but if we affain remove the
weights fiojn the plate, the mercury will
instantly recover its globular figure and
push up the glass before it

InboththeM experiments we see that
there exists an attraction between the par-
ticles of mepcurys iA the first, the globules
which are in contact with the plate of glass
leave this substance completely, they at-
tract each other and form a sphere greater
in bulk. A mere inert fluid would in any
case retain the fiffure it once possessed. It.
could not be endued with a globular form
unless a real reciprocal attraction among
its particles, took place, which in the latter
experiment is still more striking, fbr it
there is not only superior to gravitation,
but actually overcomes an external force.

THlrd^.— If aglass tube of a fine bore



be immersed in water, contained in wnf
vessel, the fluid will ascend to a certain
height within the tube above its kvel, and
its elevation in several tubes ot different
sizes will be reciprocally as the diameter
of their bores.

This kind of attraction which takes
place as well in iKkeuo as in the open air,
has been called capillary attraction. It ia
this attraction which causes water to rise
in sponee, cloth, sugar, sand, &c. for aH
these substances may be considered as fine
tubes in which the fluid ascends.

Remark, — ^The ascension of fluids ui g^lass
tubes of a fine bore succeeds best when
the inside of the tube has been previous^
moistened, which may conveniently be
done by blowing through it with the mouth.
And it the water be coloured with a little
red or black ink, its ascension will be move
obvious, pairticulari^ if the tube be bekl
against a sheet of white paper.

#Vicrf A^.— If two pUtes of glass previ-
ously wetted, be made to meet on one side*
and be kept open at the other, at a small
distance, by the interposition of a shill^^
or any other thin substance, and then im-
mersed in water, the fluid will ascend be-
tween the two plates unequally. Its upper
surfiu^ will form a curve, in which the
heights of the several points above the sur-
face of the fluid will be to one another re-
eiprocally, as their perpendicular distance
from the line in which the plates meet.
The ratio of this attraction is therefore as
the tiquares of the increments with which
thefOates open.

Here then we have two other hwtances
that an attraction prevaHs among the par-
ticles of bodies. For in both cases part of
thefluid has left the contiguous mass, ooii*
trary to the laws of gravitation. It is
drawn up as it were, or attracted by the
tube or plate of glass.

JV^A^.— If we immerse* a piece of tin,
lead, bismuth, silver, or gold, m mercury,
and draw itjout again immediately,the mer-
cury will attract the metal, and the lat-
ter w^il carry with it a portion of the
fi>rmer which will stick to it so ob-
stinately as to be videpatable by mere
friction.

There exists therefore an attraction be-
tween the diil^rent metals brought in con-
tact with each other.

S!u?C%.«'If a small stick be dipt in water
or any other fluid, and drawn - out i^^» n
drop will be found hM]irtng at the eoa of it
of a spherical form. Tht drop is spherical,
because each particle of the fluid exerts aA
equal force in every direction, drawing
otber particles towards it on every side as
far as its power extends. .

Thus the very formation of drops ob-
viously demonstrates that there must exist
a cause which produces that efl^tr This

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ATTRACnOK.



99



cuiiot be grtiFity, fcr agieeable to ezpe-
rifiDce that is rather an obstacle to the
formation rf drops ; since by the weight
4)f the particles, large globules resting on
jKilid bodies are flattened, and their regular
^herical form prevented.

To explain this phaerKunenon there re-
mains only the povirer of attraction, acting
between the particles of the liquid body ;
to if it is supposed that the particles of a
substance reciprocally attract each other
with equal force, and their aptitude for be-
ing mored upon one another be great
enou^ to overcome any impediment to
their motion, it follows by the principles of
mechanics, that the equilibrium of 4lie at*
tractive forces can only take place when
the mass has received a globular form.

Hence it is that all liquid bodies assume
a spherical figure when suffered to Ml
through the air, or form drops.
JHvinon of attraction,
Thou^ we are unable to discover the
cause ot the mutual attraction, experience
has proved to us that this agency follows
certain conditions or laws ; for similar
phenomena alwa3rs present themselves,
whenever thetircumstances of experiment
are the same.

Observaticm has taught us that attraction
takes place between bodies of the same
kind, and bo^es of a difierent kind. The
first is called attraetitn of t^gregation^ also
C9rpu9CiUar attraction ,• molecular attraction ;
and QttracHon of cotteoUm^ or the cohesi^
power.

The latter is termed chymkal aitraction,
ehymkal ajhuty, or affinity of composition,
ATTmacmov or AeemsoATioir.
Corpuscular attraction, or attraction of
cohesion or amegation, is that power by
wieans of which tbe similar particles of
bodies attract each other, and oecome uni-
ted into ooe mass, without changing, in the
kast the cfavmical properties th^ possess-
ed before their umon. The bodies may be
tn a solid, fluid, or s ei ifo t m state.

This attraction isdifleient in diflferent
bodies. It is alwavs in an inverse ratio to
the )K>wer of repuuion, or the quantity of
ealoric interposed between the particles of
the aodng bodies.

It becomes obvious from this, that the
agencjr of attnctloo of aggregation consists
in a mere successive and constant accumu-
lataon of similar ptfticles mto one mass ;
and that it produces adherence of surface,
or apparent contact in the ratio of the sur-
fiuse.

This foice is inherent in all the particles
of aU bo^n (caloric and light perhaps
excepted;) -we never find the particles of
bodies in a detached state, but constantly
in maases of greater or smaller magnitude,
made op of an indefinite number of parti-
cles united together by virtue of the force
,4{fc(Aienoii*



The simplest ease of the exertion of the
attraction of aggr^tion b that, where
two bodies placed in mutual contact with
each other form a direct imion without
changing thehr chymical properties: thus
if dinerent particles of sulphur be melted
together, they form a uniform mass or
whole, the particles of which are held to-
gether by virtue of the power of attraction
of aggregation, but the properties of the
body are not altered.

The same effect takes place when pieces
of the same metal, or particles of fesiR^
wax, &c are united in a similar manner.

The force of this attraction in solid bodies
mi^ be measured by the weight necessary
to demolish it Thus if a rod of metal^
glass, wood, Sec. be suspended in a pefrpen-
dicufair direction, and weights be attached
to its lower extremity till Uie rod is broken
1^ them, the weight attached to the rod
just before it broke is the measure of tlie
Qohesive force of the rod.

Lava ofattraeiion (^aggregation.

1. The agency of attraction of aggrega-
tion acts only at insensible distances; its
force increases as the distance of the bodies
presented to each other decreases, and as
the mahcet of spparent contact are more
numerous : thus, u we take two sections of
a leaden ball, having each a flat and smooth
surfiM:e, and press them forcibly together,
they will cohere, and a considerable eflbrt
is necessary to force them asunder : so also
two plates of glass wetted with a little wa-
ter to fill np their inequalities, when laid
together, will cohere ; and two pieces of
marble hanng each a flat, smooth, and well
polished sur&ce, when moistened and slipt
upon each other with a gentle pressure, wdl
unite, and a considerable force is required
to separate them. But if the two substan-
ces placed together, be not suflicienfly
smooth or polished, it will be in vain to try
to cause them to adhere together, for this
reason that the particles touch each other
only in a few points ; whereas on the con-
trary the particles of the former flat and
smooth surfaces touch each other in many
points. It has been noticed that a silk-worm's
thread can be interposed, but not two.

Thepressure of the atmosphere has no
influence on these experiments, for they
succeed equally well in vacu& as in the
open air.

It is on this account that caipentsrs
when they intend to glue pieces of wood
together, plane the surfaces perfectly
smooth before they apply the glue : and
that the surfaces of metals are scraped
clean before they are soldered, &c.
s Hence the attraction of aggregation al-
ways vanishes whenever the distance is
measureable, and becomes exceedingly
great whenever the distances is exceeding-
ly diminished; but the particular rate
which this power follows, ia^sti^v^^^nv



86



ATruLcnoN.



as wt li»i^ no mtfiimd nf wtm d mla g mther
the dtistance at which it acts, or ita relative
intefisi^.

3. Attraction of amei^ttion acU difier-
ently in different bocuet ; according to the
degree offeree with which it actf between
the particles of matter, the bodies appear
under different fomis.

It is on this accoiuit tiiat rock-crystal,
flint, diamond, and Tarietts o^er precious
stones are extremely bard, for the attrac-
^^ o^ aggregation unites the particles of
these bocfies with a great decree of force.
Hence a considerable mechanical effort is
necessary to disunite them.

In blocks of marble, chalk* liaie«toiie,
&c. the particles are held tosrether with a
force considerably less. In taese bodies it
|>reTents all relative motion among the par-
ticles themselves, and hence the motion
of one particle is followed by the motion of
the whole mass; orif that is impossible,
the cohesion is destroyed altogether, and
the piece breaks.

The integrant parts of wax, tallow, suet,
or lard, nuy be msde to change their situa-
tions, witha less degree of force than the
former.

In these substances the motion of one
particle of the body is not necessarily fol-
lowed by that of all the rest, neither does
that motion destroy the cohesion, nor
break them.

The particles of water, spirit, and ether,
move or slide over each other very readily i
hence their resistance is considerably less.
And lastly, vapours, the air of the atmo-
spheTe,and all the gasses,yield to the slight-
est possible impulse.

3. Attiaction of aggregation may be an-
nihilated by every effort which tends to
separate the particles of bodies.

It need hardly be mentioned that all me-
chanical forces, such as grinding, cutting,
filing, rasping, pounding, breaking, &c. ate
of this nature.

In all these oases the force ^>plied must
be more thah equal to the force of the at-
traction ; and as it waa stated before, that
the attraction of aggregation acts with dif-
ferent degrees of force between the parti-
cles of different bodies, so different clegrees
of force are necessary to destroy that at-
traction in different bodies : and hence it
is that chalk is more easily reduced to
powder tlian flint ; wood is easier broken
than lead ; lead easier than iron, &c.
CHrmcAL AFpririTT.
Chymical affinity, or affinity of composi-
tion, IS that power, by means of which the
particles of bodies, whether simple or com-
pound, attmct each other so intimately as
to produce a uniform whole, totally inse-
parable by mechanical efforts, and whose
characteristic properties are often different,
and sometimes contrary to those of its con-
stituent parts.



lift obvious ^omthb, that the paHjfiea
of those bodies which sve united if virtwi
of chymical affinity, form net a mere aggre-
gate, but an entire new body, which can
only be altered by the action of another
chymical power.

In considering this kind of al6nity,it will
be necessary to state ;— In what manner it
takes place between the particles of differ-
ent bodies ;— In wliat proportion they sf#
capable of combining ;*— .Under what con-
ditions ;-— With what degree of force they
unite;— And what takes place when a variety
ot different substances are made to act upon
each other at the same time, uoder certain
cifcuflsstances and in different proportions.

Hence chymical affinity is of greater im-
portanoe than affinity of aggregation, for
K takes place tn aH the complex operatkms
ofehymistry.

JhfteflCft rf'chyndeal afinity.

To prove that chymical amnity acts dif-
forently from attraction of aggregation;
that it takes pUce between the ultimate
constituent parts of bodies : and that It
produces substances possessing properties^
frequently very different and someUmes
contrary to those of the constituent parts^
the following experiments may serve.

1. Put into a crucible placed in a cod
fire, equal parts by weight of sulphur and
Hiercury ; stir the two substances together
for a fow minutes, sad when the sulphur is
melted, pour the contents out on a marble
dab, or a piece of glass previously warmed
and greased.

The substance obtained by this liteana is
a tulphurtt rfmersury, in which the mercu-
rv and sulphur are united by virtue of
chvmical amnity ( for the oompound haa
neither the colour, the splendour, the In-
flammability, the vQ^atUibr, nor the spe-
cific g^vity of either of its constitueiit
parts { nor can the sulphur and mercury ha
separated by mechanical means i they aie
therefore chymically united.

2. If we melt together two very msUeft.
ble and duct'de metals, for{uistanoe, tin and
iron, in equal quantities, tlie compound pro-
duced wul have totally lost the properties
which its constituent parts possessed be-
fore their union, for the alloy formed will
be a brittle metal which may easily be
broken by the blow of shammer.

3. Put two or three teaspoonfols of an
ILoueous infusion of ned cabbage or ayti^
of violets, into a wine glass of water, mix
it well, and put half the mixture into
another glass, By adding a fow drops of
sulphuric acid to one of the glmses and
stirring it, the blue will be chanj^ to a
crimson ; and by adding an alkali i for in-
stance, potash, to the other glass, the blue
fluid will be changed into a green.

If we drop carSftdly down the shies of
the gUss into the green obtained in this ex-
periment, a few drops of sulnlHiris acid,

digitized byVjOO^lC:



ATTmAOrMK*



_^ t wm be pMMfVd.at tha btltoei,

purple in the middlet and ^^een at the top.
OnaddbgaHttk alkalitb the other gbu,
containing the cruBeon* tbeie odours will
i^pear in an hireried order.

4. When equal parta of muriate of am*
mania and alaked lime, both subatancee
dndftute of odour* are intimately blended
ina atone mortaff it very pungent gaa (am-
OKonia)becoaies ovolred.

5. Water impregnated ¥dth ammonia
and coBcentratod muriatic acid, both fluids
of a strong odour* when mixed together in
proper {iroportiona^ instantly lose their
odour, and form a fluid void of smeU, (mu-
riate of ammonia.)



/^tfv¥.— nei^genoyof elqfmiaal afiaity
etiating between two or more bodies may
be doraaant, unUl it is called into action by
the interposition of another body which fre-
quently exerts no energy upon any of them
in a separate state.

Lam VI.— Th9 ratio of the eneigy of
chymical affinity acting between yariouB
bodies, is different in different substances.

£<n»yil.-^The agency of cb^mieal af-
finity if either limited, or unlimited in ce^>
tain bodies { in other words* chymical af-
flnity is capable of unidng bodies in defi-
nite, or in indefinite proportions.

Law yin.-^The energy of the efarmical
affinity of different bodies is modified in



6. Into a saturated aohition of OMTiate of proportion to the ponderable quantities of



lime, let ftU gradually concentrated sul-
phuric acid, a quantity of pungoit vapour
will become disengaged, (murialic acid
gM,) and from the two fluids will thus be
pvocLuced an almost solid compound, caU-
cd sulphate of lime.

7* Let equal parta of freah cnFstallized



the bodjea plaoed within the apheve of ac-
tion, w

Such are the leading laiwa which reguUlt
chymical affinity; th^ may.be.demonstra*
tea by experiments*

1. Chymical affinity can eaert ita action
between a number of bodies simple or



acetat of lead and acidulous sulphate of compound, and unite them chyraicaUy into



alumine and potash, be rubbed together ioi-
tlmgtely hi a atone mertar, the salme
Mixture will aoon become aoft, and laatly
fluid.

A like efiect is produced by treatinf^ in
a similar manner equal parts (^ciystalhxed
nilrate of ammonia and siilphato of sods.

A adid alloy of mercury and bismutis
and another oompoaad of lead and mercu»
ffy« all beii^ trttumted togethei^ instantly
beeome fluid.

It is obvioua ftom thia, that when chymi-
cal combination takea place* the oom-
pqund which is ^rmed does not possess
properties merely intermediate between
du»e of its component parts, but has acqui-
red others more or less neww This however
does not hold good in aUcaaea. Thereare
vaiioua oombinaCiQna In which the praper-
tiea of bodies ane only slightly altered^
Jxews tfchifmioal afimtj^.
Observation baa shown that affinity of
composition ofiers certain invariable pbeno-
Bseea, whidi being founded on m great num-
ber of&cts are regarded by cnymiats as
laws, and may be reduced under the fol-
lowing heada:

Law L— Chymieal affinitv can exert ita
action between aiamber of bodies, simple
or compound, and unite them chymically
into one whole.

Lmm IL— The efficacy of chvaaical affini«
t^ is in an inverse ratio to that of attrac-
tion of aggregation.

XowIlL— The agency of chymical affini-



whole I
. There are an infinite variety of com-
pounds, consisting of three, four, ^rt or
more simple substances in nature ; and ait
can also effect combinations in which there
are many simple bodies chymically imited
into one whole.

It frequently happens that various sm-
rate bodies presented to each other in a flu-
id, unite and form a single maas, which
possesses ail the characters of a homogene-
oua compound, and which retaina these
characters till itsxompoaition has been id-
tered by chymical means.

A considerable number of triple sslts
are known, which consists of thiee differ-
ent sobstanoes ; for instance, the common
alum of commerce ceosiata of aulphuric
acid united te alumine and potash or soda.
The salt fbnnerly called microcosmic aalt,



Online LibraryRobert HooperA new medical dictionary, containing an explanation of the terms in anatomy, physiology ... and the various branches of natural philosophy connected with medicine → online text (page 18 of 177)