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ESSAYS
AND
*
OB S ERVATION S,
' . r
PHYSICAL and LITERARY.
Read before a Society in Edinburgh,
• g
and published by them.
Volume II.
* / •;
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EDINBURGH:
Printed by G. Hamilton and J. Balfour*
Printers to the Univerfity,
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C O N T E N T S
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A r t. Pag.
I. fT’HE Defcription of a new Plant 5 by
Dr . Alex. Garden Phyjician at
Charles-town in South Carolina. *
II. A Defcription of the Matrix or Ovary of
the Buccinum Ampullatiim 5 by Robert
Whytt M. D. F. R. S. Fellow of the
Royal College of Phyficians , and Profejfor
of Medicine in the XJniverfity of Edin¬
burgh. S
III. Drawings of fome very large Bones 5 by
George Clerk, Efqy d 1 1
IV. Obfervations on Light and Colours 5 by
Thomas Melvill, M. A. 12
V. An eafy Method of computing the Parallaxes
\ of the Moon ; by - — _ 9 1
VI. A Solution of Kepler’^ Problem ; ^Ma¬
thew Stewart, Profeffor of Mathe¬
matics in the XJniverfity of Edinburgh. 105
VII. Of the Cold produced by evaporating Fluids ,
and of fome other Means of producing Cold ;
by Dr. William: Cullen Pi-'ofeffcr of
Medicine in the XJniverfity of Glafgow. 145
A R T <
C O N T £ N T . s<
9
17
Art. pag„-
• J %•> ■ ' 4 , , 1
YIII. Experiments, upon Magnefia Alba,
Quick-lime, and fome other Alkaline Sub -
. fiances ; by Joseph Black M. D . 157
IX. Of the Analyfis and XJfes oj Feat 5 by
Alex. Lind, Efq ; 226
X. The EffeBs of Semen Hyofcyami Albi j by
Dr. Archibald Hamilton Phyfician
\ 1 * 1 * . »
in Edinburgh. 243-
XI. The EffeBs of the Thorn-Apple ; by D/\
Abraham Swaine, Phyfician at Brent¬
ford. ‘247
XII. The EffeBs of Mufk in curing the Gout
in the Stomach ; by James Pringle,
m late Surgeon to the third Regiment of
Foot - Guards. 25a
XIII. An Account of an uncommon EffeB of
antimonial Wine ; by Dr. James Wal¬
ker, Surgeon and Agent for the Navy at
Edinburgh. - ‘ ; 254
XIV. An obfinate Dyfentery cured by Lime-
Water ; by James Grainger, M. D .
Phyfician at London. 257
XV. The anthelmintic Virtue of the Bark of
the wild Cabbage or Bulge-water Tree 5 by
the late Mr . Peter Duguid Sur-
** geon
CON .£* ENT L
Art. pag.
geon in Jamaica, in a Letter to Alex.
Monro fenior> M. D . & P. A . 264
XVI. The Defcription of a monftrous Feet us ;
by Mr . John Mow at Surgeon at Lang¬
holm, in a Letter to Alex. Monro jenio?\
M. D . G? P. 1 266
V *•*■**. %
XVII. The DiJJeclion of the fame Monjier con¬
tinued ; by Alexander Monro junior^
M* D . and Profijjor of Anatomy in the
TJniverfity of Edinburgh:1 270
XVIII. Bonesfound in the Ovarium of aWo-
~ ' ! man ; by Dr, George Young, and com-
municated to the Society by Dr, John Bos¬
well, Fellow 'of the Royal College ofPhyfi-
■■ ■ dans in Edinburgh. ' 273
XIX. Proofs of the Contiguity of the Lungs and
Pleura ; by Alexander Monro ' finior^
M, D. & P. A, ' 276
XX. An Account of feme 'Experiment's nmde
with Opium on living and dying Animals ;
by Robert Whytt M, D. F, R. S, Fel¬
low of the Royal College of Phyficians , and
Profefjor of Medicine in the Univerfty of
Edinburgh. 280
XXI. The Hi/lory of a compleat Luxation of the
Lhigh , in a Letter to Dr, John Ruther-
foord
CONTENT S.
$
* « * ,
Art. . Pa89
foord President of the Royal College of Phy-
fcians , W Profeffor of Medicine in the
Univerfity of Edinburgh ; by James
Mackenzie, M* D. late Phyfician at
Worcefter. 3 17
XXII. Some Obfer vat ions, on the New Method
of curing the CataraCl , by extracting the
Cryftalline Humour ; by Thom as "Young
Surgeon in Edinburgh. 324
XXIII. A Hernia from the Omentum falling
down into the Scrotum $ by Thomas Li¬
vingston, M. X). Phyfician at Aber-
dern. 333
XXIY. A Child brought forth at a Rent of the
' . 338
A Child efc aping at a Rent of the Womb
into the Abdomen 5 by Alexander
Monro, M\ D. & P. A. 339
XXV. A preternatural Collection of Waters in
the Wc mb with Fwins ; by Stephen Fell
Surgeon in Ulverftone. 342
XXVI. Hi fortes oj tophaceous Concretions in
the Aliment ary Canal ^ Alexander
Monro femor , M, D. F, Re 5. and Pro -
jeffor of Anatomy in the Univerf ty of Edin-
bur§h- • 345
XXVII.
CONTENTS.
Vll
Art> . _ Pag-
XXVII. Remarks on Procidentise Ani, Intufuf-
ceptio, Inflammation , and Volvulus of the
Inteflines ; ^Alexander Monro Jenior
. M. D . & P . A. 353
XXVIII. Hiflory of a genuine Volvulus of
the Inteflines -> by Alexander Monro
junior j M. D. <3;%/ Profefjor of Ana -
- tomy* ' ■ 368
XXIX. ^ Defcription of the American 2?/-
- Fever , ?7z ^ Fetter from Dr . John
Lining, Phyflcian at Charles-town
South Carolina, to Dr. Robert Whytt
Profeflor of Medicine in the Univerflty of
Edinburgh. ^70
XXX. Anflwer to an Objection againft Inocula¬
tion*, by Ebenezer Gilchrist M. D>
Phyflcian at Dumfries. . 396
XXXI. A Propojal of a new Method tf curing
cbflruCted Menfes ; by Dr. Archibald
Hami.ltqn Phyflcian in Edinburgh. 403
XXXII. A Dropfy unexpectedly cured ; by
Thomas Livingston M. D. Phyflcian at
Aberdeen.
XXXIII. Hiflory of a Patient ajfetted with
periodic nephritic Convulflons $ by Cornt
WELL
c O N T E n T S.;
C'O 9
mn
Art* PaS»
WELL Tathwell M. jD. Phyfician at
Stamford. , 412
XXXIV. Biftory of a Fever after Child-bear¬
ing ; by the fame. . . . 4 1 7
XXXV. Bijlory of a Fever -with badfymptoms ;
by the fame. \ ■ ,• 42°
XXXVI. Accounts of extraordinary Motions of
the Waters in fever al Places of North Bri¬
tain, and of a Shock of an Earthquake
felt at Dunbarton. , 423
ERRATA.
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page, I.4. r. 0.3190764. 1. 3. r. 2.084857. 1. I. r,
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bottom, 1. 2. r. 50°5 1**093797. p. 264. from the top 1. 5.
after Duguid dele late 0 p, 300. 1. ult, f. leramd r. learned \
X* , r * * r
ESSAYS
ESSAYS
AND
OBSERVATIONS
, < T ' > * * *\ T
# r -r *• ■ .-*■ - * «», ' . , _ ■ v . r
PHYSICAL AND LITERARY,
Article L
! The Defcription of a new Plant ; Dr. Alex¬
ander Garden, Phyfcian at Charleftoa
in South Carolina,
DOctor Garden writes DoCtor Whytt^
that, in Summer 1754, he met, about
a mile from the town of New York in
New England , with a plant 3 which, at firft*
he took to be a hypericum , but, on examining
it, found it different : upon which he took
down its characters, and fent them, fome days
after, to Mifs Jenny Colden (daughter to the
Honourable Caldwallader Colden) , a very inge¬
nious young Lady and curious Botanift. In
return to this, Mifs Colden fent Dr. Garden
the characters of a plant which proves to be
Yol, IL A the
4T
52 ESSAYS AND OBSERVATIONS
the fame : it is N° 153. of her collection ;
and was firft found by her, Summer 1753*
Uiing the privilege of a firft difcoverer, fhe
was pleafed to call this new plant Gardenia ,
in compliment to Dr. Garden .
/
The Defcription of the Gardenia, fent by
Dr. Garden to Mifs Golden.
ANONYM OS.
POLYADELPHIA EnNEANDRIA.
Radix perpendicularis, in defcenfu fibras
aliquot at plures cirros emittens, fen-
firn attenuatur, fimplex, mollis.
Caulis fimplex, fruticofus, teres, re&us,
ex alis foliorum internodiis fefquipol-
licaribus laterales emittens ramulos,
lineam craffus, cubitum plus minus
altus, cavus, annuus, glaber.
Folia fimplicia, feffilia, patula, bina ex op-
polito alternata, integerrima, obtufa,
ovata, cordata in duo auricula, circa
caulem fupra fe invicem expan fa, ad
bafin extenduntur, nitida, fuperne vi-
ridia, inferne glauca, nervo medio in^
fra
PHYSICAL and LITERARY. 3
fra prominulo, pundtis lucidis byperici
foliorum inftar perforata- - dimidium
pollicis plus minus latitudine, fefqui-
pollicari fere longitudine.
Pedunc. nunc alaris, nunc terminatrix, fili-
formis, femiuncialis.
Calyx perianthium pentaphyllum perfiftens,
foliolis linearibus, lanceolatis, acutis.
Corolla pentapetala pallide rubra, bradteis
lanceolatis, cum calyce fitum alternan-
tibus et longioribus.
Stamina. Filamenta noyem, leviter purpurea
filiformia, in tria corpora ad bafin coa-
lita. Fafciculi ifti filamentorum, in-
terpoiitione trium corporum neBareis
fimilium, a fe invicem feparantur.
Haecce corpora, colore funt bruneo-
luteo, obtufa, crafla, breviora, rece-
ptaculo feffilia, hinc modice cava, in-
de gibbofa. Anther ae fubrotundae, par-
vae, luteae.
Pistillum germen trigonum ; ftyli tres,
parum reflexi, teretes ; ftigma nullum,
vel faltem nudis oculis imperceptibile.
Receptac. parvum cyathiforme exoavatum.
Pericarp, capfula oblonga, acuminata, ob-
tufe triquetra, trilocularis, trivalvis,
tribus
4 ESSAYS and OBSERVATIONS
tribas fulcis per longitudinem decur-^
rentibus. *
Semina plurima, parva, obtufe cylindrica,
receptaculo proprio per fanem umbi-
licalem breviffimum in duobus ordini-
bus adhaerentia.
j. Hypericum inter polyadelphia polyan¬
dries collocat celeberrimus Linnaeus;
et optimo quidern jure : nam, in qua-
cunque re variant inter fe diverfae hu-
jus Tpecies, conilanter tamen exiftunt
fil amenta numerofa ; at in hacce planta
Temper novem inveniuntqr filamenta,
et Temper in tria corpora vel fafciculos
concreTcunt.
g. In hyperico nunquam occurrunt nedia-
rea ; at in anonymo Temper exsftunt
tria, conTpicua, et ftamina ab invicem
feparantia.
3. Germen et pericarpium figure. Tubro-
tunda donantur 5 at in anonymo uter-
que triquetra forma gaudet*
4. In hyperico , calyx perianth, quinque-
partitum ; at in anonymo , perianth 0
pentaphyllumo
PHYSICAL and LITERARY*' &
Mifs Col den’s Defcriptioh of the fame Plant*
: { •*- - i ^ ^ -■ * v> » * * ' i • ^
• . . " r *
N° x 53. Gardenia.
. % * w S > v *
Cover of the flower is a cup, compofed of
five lancet-lhap’d leaves continuing.
Flower is five oval-fhap’d leaves, longer
than the cup, and ipread out.
Chives are nine, placed in three bundles $
every three are joined in one body for
near half their length ; their upper
parts are fine threads ; they are a little
fhorter than the flower-leaves. The
caps are roundifh.
There are three fmail oval-fhap’d bodies,
of a bright red colour, placed on the
feat of the flower alternately with the
bundles of chives .
Pi still. The feed-bud (germen) is of a long
ovally fhape, with three deep furrows.
The files are three threads of the
length of the chives. The tips (ftigmd)
are plain.
Cover of the feed is a long oval-fhap’d
box , of a dark red colour, with three
deep furrows along it, and opening at
three
£ ESSSAYS and OBSERVATIONS
three parts at top. Before the feeds
are ripe, it contains three cells ; but
when the feeds are ripe, the divifions
feparate at the axis, and it contains
but one cell.
Seat of the feed is three ridges (being the
infide of the three furrows of the faid
box) each with two rows of feeds.
Seeds are numerous, fmall, and oval-fhap’d.
Root is fibrous ; but, tho’ fibrous, the mod
of them are about as thick as the (talk;
/
they are white and branched ; fome of
them are like fine threads.
Stalk grows fingle, is round and fmooth,
and is branched out oppofitely from
the arm-pits of the leaves.
Leaves ftand thinly in pairs oppofitely on
the ftalk and branches, they have no
leaf- ftalks, are ovaj-fhap’d, about half
as long as they are broad, broadeft in
the middle, are fmooth, have a rib a-
long the middle, with fmal! tranfpa-
rent veins extending from it towards
the edges, and the edges are intire.
The flowers are of a pale red colour ; they
ftan$i in clufters on the top of the ftalk
and
PHYSICAL and LITERARY
7
and branches , and fometimes in pairs
at the arm-pits of the /eaves.
This plant grows in wet ground, and
flowers in Augujl.
Observation. The three chives only
in each bundle, and the three oval-fhap’d bo¬
dies on the feat of the flower, together with
the feat to which the feeds adhere, diftin-
guifh this plant from the hypericums ; and,
I think, not only make it a different genus ,
but likeways makes an order which Lin¬
naeus has not.
Art.
8 ESSAYS and OBSERVATIONS
Art. IL
A Defcription of the Matrix or Ovary of the
Buccinum. Ampullatum * ; ^Robert
Whytt M. D. F. R. S. Fellow of the
Royal College of Phyficiamr and Profeffor
of Medicine in the Univerfity of Edin¬
burgh.
• * * • *»-*-*« ...•*»» u , * -
, 4
NAturalists inform us that the huccind
and purpura , the former towards the
clofe of the Winter and the latter in the
Spring, throw out a vifcid glutinous humor %
which thickening and becoming dry, forms
a congeries of cells or receptacles connefted
together, fomething refembling the cods of
white vetches, and containing the nafcent
buccina or purpura . This congeries of cells
or pods is often found upon the fhore, and
fometimes miftaken for the hardened froth
of the fea.
But whatever may be the manner in
which thefe cells are formed, the matrix s
ovary
The buccinum ampullatum is that in which the hermit*
crab is found.
PHYSICAL and LITERARY. 9
ovary or receptacle, in which the nafcent
buccina ampullata are found, has fo me thing
remarkably curious in its ftrudture.
Tab. i. fig. 1* reprefefrts the matrix , as
it is called, of the buccinum ampulla tum^ fent
me from South -Carolina by Dr. Garden ^ the
length of which was full two foot.
a a a a a, &c. are the cells, receptacles or
pods, compoling this matrix , whole number
amounted to 94. Thefe pods, towards the
extremity D, turned fmaller.
ABCD, a band or ligament connecting
he feveral cells or pods, of much the fame
and of fubftance with the fides of the cells*
out thicker and tougher.
The pods or cells are compofed of a thin*
tough, tranfparent fkin or membrane, and
contain in their cavities a considerable num¬
ber of fmall buccina .
Fig. 2. represents one of thefe cells infire*
thro' the tranfparent membrane of which
may be feen the buccina it contains.
Fig. 3. {hews one of thefe cells or pods o-
pened, that its buccina may be diftindtly feen.
Vol.IL B Fig.
xo ESSAYS AND OBSERVATIONS
Fig.. 4. exhibits fe'veral different views of
the fmali buccina , ail of their natural lize.
In fome of the pods or cells, I found 32,
in others, only 28 buccina : but, as towards
the final 1 end of the matrix the pods were
lefs, and had fewer buccina in them, we may
fuppofe that each pod might contain 25 buc¬
cina ; in which cafe, the number in the-
whole matrix muft have been 2350,
■ . j
Art,
PHYSICAL and LITERARY. n
Art. III.
Drawings of fome very large Bones > by
George C^err. Efq;
^ipAB. II. fig . i. reprefents the fcapula or
A fhoulder-blade of an animal, found in
a fhell marl-pit near the town of Drumjries ,
of a monftrous flze, meafuring in length
twenty one inches and eight tenths.
Fig . 2. is a rib twenty three inches long*
and two and two tenths broad.
Fig . 3. and 4. are alfo pieces of broken
ribs, found in the fame place ; where the
whole or greateft part of the bones of the
animal wrere afterwards difcovered, but loft
or deftroyed by the country-people who
found them.
As the bones defcribed are at leaft one
third larger than thofe of our biggeft oxen
or horfes, they are fuppofed to be the re¬
mains of an Elk or fome other animal not at
prefent an inhabitant of this country.
They are juft now in the poffeffion of
George Clerk .
Art.
% 2 ESSAYS AND OBSERVATIONS
Art. • IV.
Objervatiom on Light and Colours j by
Thomas Melvill M. A. *
SECT.' I.
On the Mutual Penetration of Light.
I • E of the firft and greateft difficulties
that occurs in reflecting on this fub-
jed, is, to conceive how it is poffible that
light
* Read January 3, and February 7. 1752.
Had the ingenious Author of this paper (who died De¬
cember 1753, at the age of 27) lived to put the fimfhlng hand
to it, he would, probably, have added many things, and
perhaps retrenched fome others, by which it would have
been rendered hill more deferving of the approbation of the
public. Mr. Melrvill ufed to obferve, that as, of all Sir
Ifaac Newtons difeoveries, thofe relating to light and colours
Were perhaps the molt curious ; it was fomewhat remark¬
able, that few, if any, of his followers had gone one hep
beyond him on thefe fubje&s, or attempted to compleat
what he had left unfinilhed. Our Author, therefore, pro-
pofed to have applied himfeJf particularly to the further il-
lullration of the theory of light and colours. The follow¬
ing eh ay is a fpecimen of what might have been expefted
from him, and fufficjently fhews the uncommon genius of
its Author, 0
V
PHYSICAL and LITERARY.
*3
light can move thro’ light in all imaginable
diredions, without occafioning the leaft
perceivable confixfion or deviation from its
redilinear courfe. Many have been induced,
from this confideration, to believe it incor-
poreal ; and all who have thoroughly weigh¬
ed the difficulty, have feen the neceffity of
afcribing a fubtility to it incomparably greater
than we are led, by any phenomena, to afcribe
to any other fpecies of bodies in Nature.
There is no phyfical point in the vifible ho¬
rizon which does not fend rays to every other
point ; no ftar in the heaven which does
not fend rays to every other ftar : the whole
horizon is filled with a fphere of rays from
every point in it ; and the whole vifible uni-
verfe, with a fphere of rays from every ftar.
In fhort, for any thing we know, there are
rays of light joining every two phyfical points
hi the univerfe, and that in contrary diredi-
ons ; except where opaque bodies inter-?
veen.
2. Those who fuppofe that light is nothing
elfe than vibrations or pulfes propagated
thro' a fubtile elaftic medium from the vifible
pbjed to the eye, may perhaps remove the
difficulty by afcribing a fufficient minute-
i4 ESSAYS and OBSERVATIONS
nefs to the particles of that medium ; fince
we fee, by experience, that found in the air,
and waves in the water, are conveyed in dif¬
ferent diredions, without fenfibly interfe-
ring : but, as that hypothecs feems infup-
portable on other accounts we mu ft endea¬
vour to accommodate our folution to the on¬
ly other conception we can frame of it $
namely, that of particles adualiy projeded
from the luminous body,
3. It is manifeft, that, tho? the mere fub-
tility of the particles of light may tend to ac¬
count for its eafy paffage, in all diredions,
thro* denfe tranfparent bodies, it will not
ferve to explain its eafy paffage thro* other
light equally fubtile : but, for this purpofe,*
it feems neceffary to fuppofe light incompa¬
rably rare when at the denfeft 3 that is, that
the femi-diameters of two of the neareft
particles in the fame or in different rays, foon
alter their emiffion, are incomparably iefs
than their diftance.
4. Let us confider a little the courfe of a
particle of light from any of the remoter fix¬
ed
•* Newtom Principia , book 2. prop. 41. and 42, See all©
pwjton s Optics, query 28.
PHYSICAL and LITERARY. 15
ed ftars to the human eye $ for inftance,
from the fmall one called the Rider in the
tail of the Great Bear : The particles by
which we fee that ftar, have, in the firft
place, palled thro’ the fpace furrounding it,
in which there are probably feveral planets
revolving, and which mull be therefore fo
filled with a fphere of rays from each of
them that they may be vifible to an eye any
where fituated in thofe fpaces ; after that, they
have palled laterally thro' the whole torrent
of light flowing from the ftar of the fecond
magnitude which we fee befide it ; and laft-
ly, they have palled likeways acrofs the
whole ocean of the folar light, and all that
light with which the fpace furrounding the
fun is filled from all the comets, planets, and
fatellites; and belides, in every phyfical point
of their numerous journey from the Rider
to our eye, they have palled thro' rays of
light flowing in all directions from every fix¬
ed ftar in the vifible univerfe : and yet, du¬
ring the whole, they have never juftled a~
gainft one particle of light ; otherwavs they
could not have arrived in their true direction
to our eye. This reflection cannot fail to
fuggeft a general notion of the rarity and te¬
nuity
I<S ESSAYS AND OBSERVATIONS
nuity of light, far furpaffmg all the fuppo-
Fitions which are ufually made about it.
ij. The chance which any one body has
to juftle with others of like magnitude, is
leffened in proportion to the bulk of the bo¬
dies with refpedl to the fpace in which they
move. It mud be therefore fuppofed, as
we mentioned above, that the diflance of the
neared particles, flowing in the fame and
in different lines, mud exceed their diame¬
ter, not indeed infinitely, but a number of
times utterly incomparable with' all cur ordi¬
nary numbers, in order that a particle may
efcape in one phyfical point of its progrefs i
but, that it may pafs freely on, thro’ the
whole didance of the remoteft fixed flars, it
is evident, that this proportion of excefs
mud be multiplied by a number again incom¬
parable. But this excefs, fp increafed, mud
be railed to a power whofe exponent is an um¬
ber equal to the number of all the fixed flars,
planets, and comets. And Sadly, if there is an
eladic medium diffufed thro’ the mundane
fpace, as the propagation of heat-* and ma¬
ny other phenomena feem to insinuate y this
lad number mud be at lead doubled, if we
Would
* Newt. Opt. (jueries. ad fins
PHYSICAL and LITERARY. if.
wcfuld exprefs the proportion in which the
diftance of the neareft rays exceed the dia¬
meters of their particles : and yet this di¬
ftance of the neareft rays, flowing from the
fame center, is fo incomparably below our
fmalleft meafures, that there is no poftibility
of defining it.
6. Had Euler confidered this extreme ra¬
rity, as well as tenuity of light, which muft
be acknowledged by all who fuppofe that its
particles are actually projected from the lucid
body, he would not have alledged, that
this opinion is inconfiftent with the freedom
and perpetuity of the celeftial motions**.
7. Some have thought, that, if the parti¬
cles of light repel one another, their mutual
perturbation may be prevented : but the
contrary is manifeft upon the leaft reflection*
for tho’, by that means, the particles might
be prevented from ftriking, they muft in-
ftantly turn one another from their redtilinear
courfes, as foon as they come, in different
directions, within the reach of their mutual
powers. Thus, we find by experience, it is
jmpoffible to make one ftream of air pene¬
trate another without confufion * for the two
ftreams either unite into a common one with
Vol. II. C an
* See his Nova theoria Iticis et colorum,
1
1
i8 ESSAYS and OBSERVATIONS
an intermediate diredtion, or produce irregu¬
lar eddies.
8. Here, by the bye, we may fee that the
ingenious fyftem of Bofcovich , the Roman
Profeffor, concerning the elements of mat¬
ter whatever may be faid for it from other
confiderations, gives us no aftiftance in com¬
prehending the mutual penetration of light;
for indivifibie points, endued with an infu-
perable repulfive power, reaching to a finite
diftance, are as fubjedt to interfere, as fokd
particles of a finite magnitude.
<* i
SEC T. II.
On the Heating of Bodies by Light .
9. It appears, by Sir Ifaac Newtons expe¬
riments on the inflexion of light, that bo¬
dies adt upon it at fome diftance ; and that
the fame power, varioufly exercifed in va¬
rious circumftances, is the caufe, likeways,
of refradiion and reflexion. We know no
inftance of any kind of attradtion or repul-
fion in Nature which is not mutual ; we ob¬
serve Lkeways that bodies are heated by the
influence of the fun's rays : it is therefore na¬
tural
5 See his Divert, de lumine etde viribus vivi3.
PHYSICAL and LITERARY.
*9
iural to look upon this- as the effeCt of the re¬
action of light upon bodies, and that, at a
diftance from them ; for, there is no reafon
to think that light produces heat by actually
striking the foiid parts of bodies, after we
are fatisfied that bodies produce the reflexion
and refraction of light, without fuffering it
to come into contaCt with them.
lOo From thefe principles it follows, that
light, in pafling out of one medium into an¬
other of different denfity, muft always pro¬
duce fome degree of heat ; becaufe it is part¬
ly refraCted and reflected at the common fur-
face : fecondly, that, in pafling forwards
thro’ the fame homogeneous or perfectly
tranfparent medium , it can produce no heat ;
becaufe there is no reflexion or refraction,
no influence of the body, upon the light, but
every ray purfues its own right-lined courfe,
as if it moved in a perfeCt void
ii. Hence it appears, that, in water,
glafs, and other tranfparent mediums , which
are
# Sir Ifaac Newton, in the third book of his Prhtcipia ,
where he difputes concerning the tails of comets, lays it
down as an obvious principle, Quod radii folis non agit-ant
media qiue permanant , nifi in ref ex tone et refradions ,
:M ESSAYS AND OBSERVATIONS
are warmed by the fun’s rays, the heat muft
be propagated from their iurfaces towards
their central parts
12. Hence hkeways we underftand why
opaque bodies are fooner heated by the fun-’
beams than tranfparent ones 5 fince, there are
innumerable reflexions and refractions within
their fubftances, befides what happen in
common with tranfparent bodies at their fu-
perficial parts. As each colorific particle of
an opaque body, by the reaction of the par¬
ticles of light, muft be fomewhat moved
when the light is reflected backward and for¬
ward between the fame particles, it is ma~
nifeft that they likeways muft be driven
backward and forward with a vibratory mo¬
tion 5 and the time of a vibration will be e-
qual to that which light takes in moving
thro’ a particle, or from one particle of a
body to another adjoining. This diftance in
moft folid opaque bodies cannot be fuppofed
greater than TTf-~th of an inch, which
fpace
1 have found, by repeated trials, that the heat of wa»
tei ^eeP lakes decreases regularly from the furface down”
PHYSICAL and LITERARY. 21
fpace a particle o£ light ddcrihes in
*-,h of a fecond. With fo
12500060® *000000
rapid a motion therefore may the inter¬
nal part of bodies be agitated by the influence
of light, as to perform 125,000,000,000,000
vibrations or more in a fecond of time J The
arrival of different particles of light at the
furface of the fame colorific particle in the
fame or different rays, may difturb the -regu¬
larity of their vibrations, but will evidently
Increafe their frequency, or raiie ftiil mi¬
nuter vibrations among the parts which com-
pofe thefe particles ; by which means the
inteftine motion becomes more fubtile and
thoroughly diffufed. If the quantity of light
admitted into the body be in area fed, the vi¬
brations of the particles mud like ways in¬
creafe in magnitude and velocity 5 till, at laft,
they may be fo violent as to make all the
component particles dafh one another to
pieces by their mutual collifions : in which
cafe, the colour and texture of the body mud
be deflroyed. Thus may we form, from
known principles, fome imperfect conce¬
ption of the manner in which bodies are
heated and burned by the addon of light :
More than an imperfedt notion of thefe fe-
cret
2 2 ESSAYS AND OBSERVATIONS
cret operations of Nature is not to be expects
ed ; for they certainly depend, in great
meafure, upon laws and principles utterly un¬
known to us.
13. If one beam or ray of light, by paf-
ling ftraight onwards thro’ the fame pellucid
fubftance, can communicate no heat to its
internal parts ; neither will the greateft
quantity of rays; tho’ crowded into the nar¬
rowed: fpace, by croffing one another. From
hence it follows, that the portion of air
which lies in the focus of the moft potent
fpeculum is not at all affefted by the paflage
of light thro’ it, but continues of the fame
temperature with the ambient air ; altho*
any opaque body, or even any tranfparent
body denfer than air, when put in the fame
place, would be ijitenfely heated in an in*
Rant.
14. This confequence, evidently flowing
from the plaineft and moft certain principles,
ieems not to have been rightly underftood
by many philofophers ^ : for which reafon,
' ‘ I
See Boerhaave element, chem. tom. 1. on Hre, corolL
5. after exper. 14. and coroll. 1. and 7. after exper. 17.
See alfo Ruth erf orth's fyftem of natural philofophy, prop.
366%
PHYSICAL and LITERARY* 23
I thought it might be worth while to fey
fomething in explication of it. The eafieft
way to be fatisfied of the matter experimen¬
tally, is, to hold a hair or down immediately
above the focus of a lens or fpeculum , or, to
blow a ftream of fmoke from a pipe hori¬
zontally over it ; for, if the air in the focus
were hotter than the {unrounding fluid, it
would continually afcend upon account of
its rarefaction, and thereby fenfibly agitate
thefe {lender bodies. Or a lens may be fa
placed as to form its focus within a body of
water or fome other tranfparent fubftance,
the heat of which can be examined from
time to time with a thermometer : but care
mu ft be taken in this experiment to hold the
lens as near as pofiible to the tranfparent bo¬
dy ; left the rays, by falling clofler than or¬
dinary on its furface, fhould warm it more
than the common fun-beams.
1 5. It is well known that the rays of light,
by pafling obliquely thro’ our atmofphere,
are
366. of the agronomical part; and Nolet lemons de pbyfique,-
torn . 4. The filence of moft phyfical writers, con-
*
cerning this paradoxical truth, makes it probable that they
were unacquainted with it.
u ESSAYS AND OBSERVATIONS
are infleCted into a curve by the continued
infraction anting from the continual increafe
of its denfity ; therefore they muft produce
fome degree of heat in every part of their
progrefs thro' it [N° io,]; But, as the
whole fucceflive refraction is juft equal to
the Single refraCtion that would be made in
paffing at once from the celeftial fpaces into
a medium as denfe as the loweft part of our
atmofphere and all the fucceflive refle¬
xions that can be made from every different
Jiratum , are but equal to what would be
made at once from the furface of a medium
' of the fame denfity ; it eafily appears, by
comparing the densities of air and water, and
their refpedive figns of refraCtion, that all
the refraCtion and reflexion which the whole
depth of our atmofphere produces is much
lefs than what happens at one furface of wa-
tei ; and consequently, the heat produced in
our atmofphere, by the immediate aCtion of
light upon it, muft like ways be much lefs
than what is raifed in water. The air
feems to have the greateft part of its heat
communicated to it from the opaque vapours
which
* ^ewtt °Pt4 2. part 2. prop.
PHYSICAL and LITERARY. 5*5
which float in it and the general furface of
. fea and land to which it is contiguous.
, SECT. III.
On the Jilver-like Appearance of Drops of
\
Water on the Leaves of Colewort*
1 6. It is common to admire the volubility
and luftre of drops of rain that lie on the
leaves of colewort and fome other vegetables ;
but no philofopher, as far as I know, has put
himfelf to the trouble of explaining this cu¬
rious phenomenon . Upon in fpe cling them nar¬
rowly, I find, that the luftre of the drop
arifes from a copious reflexion of light from
the flattened part of its furface contiguous to
the plant : I obferve further, that, when the
drop rolls along a part which has been
wetted, it immediately lofes all its luftre 5
the green plant being then feen clearly thro"
it : whereas, in the other cafe, it is hardly to
be difcerned.
ij. From thefe two obfervations laid to¬
gether, we may certainly conclude, That the
drop does not really touch the plant when
it has the mercurial appearance, but hangs
V ol. II, D
m
ESSAYS and OBSERVATIONS
in the air ' at fome distance from it, by the
force of a repul five power , for, there could
not be any copious reflexion of white light
from its under fur face, unlefs there were a
real interval between it and the furface of the
plant** [See Tab. iii. Fig. 2 .]
18. If1
* Newt. Optics, query 29.
Let AB, Tab. iii. Fig. 4. reprefent the extremity of
any repulfive body immerfed in water, for inftance a flice
of cole'worf leaf, CL and DM, the convex furfaces of
water immediately furrounding it, and GD perpendicular
to AB, the common tangent of thefe curves, which
will Be the continuation of the general furface of the water.
The forces with which any two particles, E and F, are
preiTed by the water in the directions EG, FH perpendicular
to KB, are known to be as KG and KH, and the repulfive
powers which balance them muft be in the fame proportion.
If therefore the relation between the ordinate and abfcifs in
r
the curve DM could be any way found by experiment, the
law of the repulfive power might be determined, upon fup-
pofkion that the particles are influenced by no force but the
repulfive power of the line KB and the gravity of the fuper-
incumbent fluid ; but their mutual attraction, which tends to
leflen their lateral tendency, mufl be likeways taken into the
account in order to an exadt determination.
Before I leave this fubjedl of attra&ion and repulfion, I
beg leave to propofe to the Society, the fpontaneous motions
of light bodies on the furfaces of fluids, as a thing worthy of
being inquired into ; for, tho’ it be manifefi: in general that
they depend upon the different figures of the furface, it is far
from being an eafy matter to explain the particular cafes by
siechanical or hydroftatical laws. The following account
g£
\
PHYSICAL and LITERARY. 27
18. If that furface were perfedly fmooth,
the under furface of the drop would be fo
likevvays ; and1 would therefore fhow an
image of the illuminating body by reflexion,
like
of the phenomena may be ufeful towards fuch an enquiry*
Cafe 1 . Suppofe a fluid which is attracted to the fide of its
containing veflel, a;nd confequently is elevated, at the odes,
into a concave furface : If a body be immerfed which at¬
tracts the fluid, and is therefore furrounded likevvays with a
concave elevation of the fluid ; as foon as the two elevations
begin to join, the body will move towards the fide of the
veflel with an accelerated motion. Cafe 2, Suppofe a fluid
which is formed into a convex furface, either by the repul-
five power of the containing veflel or cohefive force of its
own particles : If a light body be immerfed which attracts
the fluid ; as foon as its furrounding elevation begins to join
with the lateral depreffion of the fluid, it will begin to move
towards the middle of the vend ; and, if it be brought by
force towards the fide, it will recede from it again with an
accelerated motion.
1 4 J ’
In both the firft and fecond cafes, if the attracting
body be held faff, and the whole fluid made eafily moveable
with its containing veffel, it will remove to or from the at¬
tracting body in the lame manner as the attracting body did
with refpeCt to it ; i e. in the flrfl cafe, the whole fluid will
move fo that the attracting body may come to its edge ;
and in the fecond, fo that it may recede from it. Cafe 3.
If, in a fluid which is attracted by the fldes of its veflel, a
body be immerfed which repels the fluid, and is therefore
Unrounded with a ditch or convex depreffion of the fluid ; as
foon as that depreflion begins to join the elevation of the
fluid a: the Tides, it will recede towards the middle ; and, if
forcibly
28 ESSAYS AND OBSERVATIONS
filver : but, as it is
con fide r ably rough and unequal, the under
furface becomes rough likew&ys $ and fo, by
reflecting
forcibly brought to the fide of the veffel, will fly from it with
an accelerated, motion. Cafe 4* If» m a fluid which is rormed
into a convex furface at the fldes, a repelling body be im-
pierfed ; as foon as its depreffion begins to unite with the la¬
teral depreffion of the fluid, it will move towards the fide
with an accelerated motion. In thefe two laft cafes, the
fame pbfervation holds as with refpeft to the firft and
fecond, *oix. that the whole fluid will move with correfpon-
dent motions by the force of reaction, if the repelling body
be held faft. Qafe If two bodies be immerfed in a fluid,
which each of them attracts ; as foon as their elevations
begin to join, they will rufli towards one another with equal
forces and accelerated motions, and continue to adhere to¬
gether, Cafe 60 If two bodies be immerfed in a fluid
which they repel ; as foon as the two deprefiions that fur-
round them begin to interfere, they will likeways rofh to¬
gether with an accelerated motion. Cafe 7. If two bodies
be immerfed in a fluid, the one of which attracts and the
other repels it j as foon as the depreffion furrounding the one
begins to join with the elevation of the other, they will mu¬
tually fly from each other. Lajily , If a body be immerfed
in a fluid which it attradls i.n one part and repels in another,
it will approach to or recede from other bodies and parts of
the fluid, differently according to its fltuation, by the rules
above laid down.
r « ' . 5 • _
The different figures aferibed to the furface of the water
in thefe feveral cafes are plainly difcernible by the fight :
if the experiments are made with candle-light, they are dif-
tinguifhed by the fhadowy or luminous rings which they
PHYSICAL and LITERARY. 29
reflecting the light copioufly in different
directions, afiumes the refplendent white
colour of unpolifhed filver.
19. After it is thus proved by an opti¬
cal argument that the drop is really not in
contaCt with the plant which fupports it, we
eaffly conceive whence its wonderful volu-
projedt on tlie bottom of the veffel, according as they are
convex or concave.
Some writers have been fo inattentive as ^o afcribe the
motions in the firft cafe to an immediate attraction between
the fwimming body and the fide of the veffel. See Heljhams
Leftures. Before I had obferved the fourth and hxth cafes,
I thought the phenomena might be all explained from this
principle, that the light bodies always tend to the higheft
parts of the water. It has been fuggefted to me by fome,
that this tendency, combined with the greater or leffer im-
merfion of the bodies, upon account of the ring of water
^vhich they elevate or deprefs, may produce all the different
cafes: and by others, that the whole is explicable from the
Tingle principle of attraction between the parts of water
which caufes two drops to run into one. I believe it will
be found, on due confideration, that none of thefe accounts
is fatisfadtory : but there is no reafon to defpair of coming
to the bottom of thefe phenomena ; fince other motions of a
like kind have been l'uccefsfully explained. Thus the run¬
ning of a drop of oil towards the concourfe of two glafs-
planes and the motion of a bubble on the furface of liquors,
when the glafs is held obliquely towards that point, where
the glafs is inclined to the liquor in the fmalleft angle, are
eafily underftood from the diredtion of the compound force
with which the drop and bubble are adleqi.
ESSAYS and OBSERVATIONS
30
bility arifes, and why it leaves no tradt of
moifture where it rolls.
20. From the like reafoning, we may
conclude. That, when a fmooth needle is
piade to fwim, it does not any where touch
the water, but forms around it3 by its repul-
five power, a ditch or bed, whofe concavity
is much larger than the bulk of the needle.
[See Tab. iii. Fig. 3.] And hence it is eafy to
underftand how the needle fwims upon a fluid
lighter than itfeif ; fince the quantity of
water, difplaced by it, may be equal to the
weight of the needle. Phenomena of this
kind, inftead of being reduced to hydrofla-
tical principles, are commonly attributed to
the mere tenacity of water, and even ufed
for meafuring its cohefive power. See Muff-
ehenbroeck , Elementa Phyfices „
21. This inftance furnifhes us with a juft
and neceffary correction of the common hy~
droftatical law. That cc the whole fwimming
body is equal in weight to a quantity of
fi£ the fluid whofe bulk is equal to that of
V the part immerfed for, to comprehend
this, as well as all ordinary cafes, it fhould
be laid more generally, That £C the whole
weight of the fwimming body is equal to
the
£C
PHYSICAL and LITERARY. p
££ the weight of the quantity of the fluid dik
placed by it,
22. These Phenomena appeared to me
-%r
worthy of obfervation here : both becaufe
they (hew the fertility of optical principles in
leading to the knowledge of things other-
ways inacceflibk ; and becaufe they exhibit
a clear fpecimen of a repulfive power, flmilar
to that which we fuppofe neceflary for the
reflexion of light from the anterior furface
of a denfer medium . Nor do I fee how it is
poflible to account for the fufpenfion of the
drop in the air by comparative attractions ;
into which feme other appearances of re-
pulfion have been, perhaps, not unfuccefs-
fully, refolved*.
4
SECT. IV.
On the Change which coloured Bodies undergo
in different Lights .
23. Sir Ifaac Newton has abundantly
proved, by a variety of arguments, that the
ordinary colours of natural bodies arife folely
from
* See Jurin on capillary attraction, at the end of Gate's
hydrojlatical Lsftur&i*
32 ESSAYS AND OBSERVATIONS
from the compounded colour of thofe rays
which they refledt 3 their colour being deno¬
minated by the fpecies of thofe primitive rays
which they refledl in greateft plenty : but
this part of the Newtonian dodtrine will re¬
ceive further confirmation by examining the
different colours which the fame body
affumes when illuminated by different lights $
and which may be called, in diftindtion
from the former, their extraordinary colours.
24. Bodies of all the principal colours,
viz. red, yellow, green and blue, are very
little altered when feen by the light of burning
fpirits : but, if falts be continually mixed
with them during the burning, different
changes enfue.
25. When fal ammon. potafh or alum
are infused, the colour of red bodies appears
fomewhat faded and dirty : green and blue’
appear much the fame as in candle-light 3,
both being .faint and hardly diftinguifhible i
white and fellow are fcarcely at all affedied.
26. When nitre or fea-falt are plentifully
mixed with the burning fpirits, and the
whole is fhrred about brifkly ; the brighteft
red bodies, feen by the light then emitted,
are reduced to a dirty t^wny brown, that
fee ms
PHYSICAL and LITERARY. 33
*
feems to have nothin g of rednefs in it :
green is transformed into another fort of
brown, only diftingui (liable from the former
by a certain inclination to a livid olive-co¬
lour ; when nitre is mixed with the fpirits,
one may fllll fee fome remains of a greenifti
colour, unlefs it be poured in very plenti¬
fully : dark blue is hardly to be known
from black, except that it appears the deeper
black of the two : light blue is changed
into a very light brown of a peculiar kind :
white a (Tames a livid yellowifh caft : and
yellow alone appears unaltered and ex¬
tremely luminous. Thefe experiments I
made with different forts of rich-coloured
bodies, as fiiks, cloths and paints0 Polifhed
copper, which has contradled from the air a
high-flaming colour, is reduced by the fame
light into the appearance of yellow brafs $
the faces and hands of fpecfators appear
like thofe of a dead corpfe ; and other mixed
colours, which have red or green in their
compofition, undergo like changes.
27. Having placed a pafte-board with a
circular hole in it between my eye and the
flame of the fpirits, in order to diminifh
and circumfcribe my object. I examined the
Vol, II, E conftitutiari
34 ES'SAYS and OBSERVATION'S
conftitution of thefe different lights with a
prifm, (holding the refradling angle upwards^
and found, that, in the firft cafe [N° 25.],
when fal ammon. alum or potafli fell into
the fpirits, all forts of rays were emitted, but
not in equal quantities ; the yellow being
vaftly more copious than all the reft put
together, and red more faint than the green
and blue.
28. In the light of fpirits mixed with nitre
or fea-falt, I could ft ill obferve fome blue,
tho’ exceffively weak and diluted : with the
latter, the green was equally faint ; hut,
with the former, pretty copious. But, when
either of thefe falts were ufed, I could hardly
fee any veftige of the red at all, at leaft
when they were poured in plentifully, and
the fpirits conftantly agitated. At every
little intermiffion indeed the red rays would
fhow themfelves very manifeftly below the
hole, and red bodies feen by that light re¬
lumed fomewhat of their ordinary colour :
and it was very entertaining to obferve how
both would evanifh again at once, as foon as
the faking and ftirring were renewed.
The proportion in which the bright
yellow exceeds the other colours in this light,
is
PHYSICAL and LITERARY.
35
Is ftill more extraordinary than in the
former: infomuch that the hole feen thro’ the
prifm appears uniformly of this yellow, and as
diftindly terminated as thro’ a plain glafs ; ex¬
cept that there is adjoining to it on the upper
fide a very faint ft re am of green and blue.
f
White bodies illuminated with it, appear alfo
thro’ the prifm perfectly well defined ; both
which are very furprizing .phenomena to thofe
who have been accuftomed to the ufe of the
prifm in other heterogeneous lights, where it
never fails to throw confufion on the extre¬
mities of all vifible objeds.
29. Because the hole appears thro5 the
prifm quite circular and uniform in colour ;
the bright yellow which prevails fo much
over the other colours, muft be of one de¬
termined degree of refrangibility ; and the
tranfition from it to the fainter colour ad¬
joining, not gradual, but immediate.
30. Upon examining foap- water-films in
the fame light, 1 could only obferve lumi¬
nous bands feparated by dark ones ; the green
and blue being too weak to affed my eye in
this view. It would be needlefs labour to
enter here into a particular detail of the rea-
fons of the different transformations of co¬
loured
o& ESSAYS and OBSERVATIONS
loured bodies, above related [N° 24, 25, and
26.] 5 fince, in general, it is evident enough,
that they are owing to the dirterent compo-
fitions of the lights with which they were
illuminated : the experiments with the
prifm [N° 27, 28.] are of themfelves a
Sufficient commentary upon the reft,
SEC T. V,
A Remark on Euler’s Nova Theorla Lucis et
Colo rum,
/ ir
31. Euler, in that treatife, (publifhed
lately along with fome other tradts, under
the title of Qpufcula Mathematic a) endeavours
to amend the Huygenian hypothefis of vibra¬
tions, and fupport it again ft the objediions
which made Newton and his followers rejedt
it : we ftiall not enter here upon the difcuf-
iion of that queftion j as it would require a
difcourfe of comiderable length ; and the
rather, that the Newtonian theory of light
and colours depends not on any particular
hypothefis with refpedt to the intimate nature
of light (in like manner as his fyftem of u-
niyerial gravitation is independent of all hy-
pothefe$
PHYSICAL and LITERARY. 35?
pothefes concerning the caufe of gravity).
In his Optics, he lays down his difcoveries
at full length, without ever inquiring whe¬
ther light con lifts in vibrations propagated
thro’ a fluid or of particles proje&ed in
ftraight lines from the luminous body : and,
in his queries, where he touches this mat-
ter *, he feems to be more pofitive in rejedt-
ing the hypothefis of vibrations, than in efta-
blifhing any other.
32. But Euler likeways advances a new no¬
tion with refpedi to the origin of colours in
opaque bodies, which is intirely inconftftent
with the principal part of Sir Ifaac Newtons
dodtrine, He fuppofes, that coloured bo¬
dies reflect the fun’s incident white light from
their anterior furface ; but, that the particu¬
lar fpecies of light, by which they appear
coloured, is properly emitted by the parts of
the body : for inftance, he imagines that
vermilion does net appear red by a more co¬
pious reflexion of red than of other incident
rays, but by the new emiffion of red rays
from the particular velocity of vibration
which its elaftic parts are capable of concei¬
ving by the impulfe of the incident light.
33- lT
* Ns%vt, Opt, quer. 28. and 29.
3S ESSAYS AND OBSERVATIONS
33. It is a fufficient refutation of this
fyftem, that no phenomena prove or require
its exiftence : whereas Newton s theory not
only folves the phenomena, but is diredtly
drawn from a multitude of experiments. Ac¬
cording to Euler s hypothecs, a body of one
colour, placed in homogeneous light of an¬
other, ought not to appear of the colour of
the light, but of a middle one between that
and its own natural colour 5 which is contra-
ry to experience
34. If it fhould be faid. That none of the
incident light is capable of qualifying the
body for emitting its proper colour, but rays
of the fame colour : that which he calls
new light emitted will be, in his fcheme,
more properly incident light refledled.
35. The chief or only fa 61 which feems to
have led him into that opinion, is, that there
are many coloured bodies, fuch as metals,
which are capable of receiving a fine polifh ;
and therefore of reflecting regularly the i~
mages of other objects, and at the fame time
retain their proper colour by which they are
feen in all pofitions. Ehat light by which
we fee in them the images of ether cbjeffs,
he
Newt. Opt, book 1, part 2. prop, ics
PHYSICAL and LITERARY, y*
he acknowledges to be incident light pro-*
. perly refleded j but the other, he fuppofes, is?
properly emitted from the colorific parts of
the body. But what neceffity is there of re¬
curring to this fuppofition, when we know,
previoufly, that the component parts ^ of all
opaque bodies are tranfparent ; that, from
every tranfparent body, there is a double re¬
flexion ; part of the incident light being re¬
fleded at the firft fur face, and a part of what
paffes thro’ the firft, refleded at the fecond ?
and when we know, further, that very thin
bodies, (as foap-bubbles, Mi{f'covy -glzfs, and
air in a fradure of glafs or ice, or between
two lenfes) while they refted feme rays of all
colour from the firft furface, refled only
particular colours at the fecond •f ? Do not
thefe fads lead us naturally to fuppofe the
firft fort of light to be only a part of the in¬
cident light refleded from the firft furface
of the body ; and the fecond, a part of what
had pafied on, refleded from the pofterior
furfaces of the fuperficial particles ?
* Newt. Opt. book. 2. part 2. prop. 2.
f Ibid, book 2. pajrt 3. prop, 12,
SECT,
40 ESSAYS and OBSERVATIONS
SECT. VI.
Concerning the Caufe of the different Refrangi -
bility of the Rays of Light
f
36. In order to account for the different
tefrangibility of the differently-coloured rays.
Sir Ijaac Newton and feveral of his follow¬
ers have fuppofed, that their particles are of
different magnitudes or denfities : but, if
there be any analogy between gravity and the
refractive power, it will produce equal per¬
pendicular velocities in all particles, whate¬
ver their magnitude or deniity be ; and fo
all forts of rays would be fall equally re¬
frangible.
37. It feems therefore a more probable
opinion, which others have advanced, that
the difterently-coloured rays are projected
with
* Altho’ the dodrine contained in this fedion has been
already publifhed in the Philofophical Tranfadions for 1 75 3,
(vid. vol. xlviii. part 1. p. 262, &c.) having been communi¬
cated to the Royal Society, by the Author, in a letter to
the Reverend Dr. James Bradley D. D. F. R. S. ; yet it
could not be omitted here, on account of its connexion with
fome of the queries that follow ; belides that it contains fe¬
veral illultrations not to be found in the Tranfadions,
f Newt. Opt. query 29*
I
PHYSICAL' and LITERARY, 4*
With different velocities from the luminous
body: the red, with the greateft ; violet,
with the leaf! ; and the intermediate colours*
»
with intermediate degrees of velocity 2 for5
upon this hypothecs* it is manifeft, that
they will be differently refracted in the pris¬
matic order 5 according to obfervation Since,
according to Sir Ifaac Newtons dodtrine of
refraftion now generally received, the velo¬
city of a ray, after entering any new medium *
is, to its former velocity, as the fine of inci¬
dence to the fine of . refradfion Y; if all thd
colours move with ftqual fwiftnefs in any one
medium , their velocity will necefiarily be¬
come unequal, upon entering a denfer medium $
in the inverfe proportion of, their feveral
fines of refrangibility : tho> we fnppofe,
therefore, the fun’s rays to be emitted with
one common velocity, it will follow that
their velocities are unequal in air, glafs, wa¬
ter, or any tranfparent body, whole refra¬
ctive denfity differs from that of the Tolar at-
mofphere This confideration is fufficient
to take off the appearance of improbability
from our hypothecs.
Vol.IL P
* Nenvtoni Piincipia, lib. I. prop. 95.
}■ Sss below, qnery
38. Oh
4 2 ESSAYS and OBSERVATIONS
38. On fuppofition that the different re-*
frangibiiity of the rays of light arifes folely
from their different velocities before inci¬
dence ; thefe velocities rauft be, to one an¬
other, nearly as their fines of refraction.
39. Sir Ifaac found their fines of refra¬
ction from glafs into air, beginning from
the extreme violet* to be ^ as 78, 77-^, ,
77b 77 b 77b 77b 77> the fine of in~
cidence being 30 : from whence their fines
of refradtion out of air into glafs, begin¬
ning from the extreme red, and ending with
the extreme violet, are found to be as -f
78000, 77873, 77797, 77663,. 77496,
77330, 77220, 77000 ; the fine ofincidence
being 120 120. Thefe numbers, therefore,
nearly exprefs the velocities in air, of the
feveral rays, before their incidence J.
40. Hence
* Newt. Opt. book i. part 2. prop. 3.
•f The extreme fines are plainly reciprocal to the former;
and thofe of intermediate colours are fourth proportionals
£0 the fine in Sir Jfaac's experiment, 77 and 78.
J The quantities which give the accurate proportion of
the velocities, before incidence, mu ft be in a conftant ratio :
the fines of refraction, by which the above calculations are
made, have this condition : but, it is otherways manifeft,
that they give only a grofs approximation to the truth.
From
PHYSICAL and LITERARY. 43
40. Hence their velocities in any other
medium , may be found j for, they are, to
thefe.
From what follows, perhaps, an exadter computation might
be made, if a proper mean angle of incidence were made
ufe of, altho’ the quantities in the canon are really not in a
conftant ratio.
Tab. iii. fig. i. Let two rays, falling in the fame line of
incidence IC, with different velocities, upon AB the furface
of a denfer medium , be refradted into different lines CR, C V.
Taking any line CD in the perpendicular to reprefent the to¬
tal adtion of the refradling power on the lels refrangible
ray, and CE on the more refrangible : If, thro’ D and E,
parallels to IC be drawn, meeting the refradled rays in
V, R and G ; it is plain, that CR, CV will be, as their
refpedlive velocities after refradlion ; and DR, EV, as their
velocities before incidence. Since the whole acceleration
which a given power produces in a body, is, ceteris paribus ,
as the time in which it operates ; CD muft be to CE near¬
ly as the time which the fwifter ray takes to pafs thro’ the
refradling fpace, to that which the flower ray takes in paf-
fing thro’ the fame, inverfely , as their velocities before inci¬
dence ; that is, as EV to DR : but CD is likeways to CE as
DG to EV ; therefore DR, EV and DG, are continued
proportionals; therefore DR is to EV in the fubduplicate
ratio pf DR to DG : but DR is to DG in a ratio compound¬
ed of DR to DC, and DC to DG, that is, in the com¬
pounded ratio of S, DCR to S, DRC and of S, DGC to
S, DCG ; wherefore DR is to EV in the fubduplicate r«a-
tio of S, DCR X S, DGC to S, DCG X S, DRC; that
is, “ The velocities before incidence are nearly in the diredfc
“ fubduplicate ratio of thefe fines and the reciprocal fub-
<* duplicate ratio of the fines of the exceffes of the common
f* angle of incidence above the feveral angles of refradUpn.1!
44 ESSAYS and OBSERVATIONS
thefe, as the fins of incidence to the fine of
refradion, .when a ray paffes from air into
the given medium
41. While the differently-coloured rays
are fuppofed to move with one common ve¬
locity, any pulfes, excited in the ethereal
medium , mu ft overtake them at equal di-
ftances 5 and therefore the intervals of re-
« flexion and tranfihiffion, if they arife in this
manner, a§ Sir 1/aac Newton conjectures,
^vould be all equal : but, if the red move
fwifteft, the violet floweft, and the interme¬
diate colours with intermediate velocities \
it is plain, that the fame pulfes muff over¬
take the violet fooneft, the other colours in
their order, and, laft of all, the red ; that
is, the intervals of the fits muft be leaft in
violet, and gradually greater in the prifma-
tic order , according to obfervation.
42, As the proportion between thefe inter¬
vals in red and violet can be affigned by ex¬
periment, and the proportion of their velo¬
cities in any medium likeways, by N° 40. ;
the velocity of the ethereal pulfes in any me¬
dium, and their diftance from one another,
pay be thence computed by the following rule:
V Multiply
f Newt* Princip. lib, 2, prop, 9;
PHYSICAL and LITERARY. 45
u Multiply the product under the velocities
fc of the red and violet rays by the difference
<c of the intervals of their fits ; then divide
by the difference of the two produces
cc which are formed by multiplying the in-
<£ terval of the fits in red by the velocity
<£ ©f the violet, and the interval of the fits
cc in violet by the velocity of red the quo¬
tient fhall exprefs the velocity of the ethereal
pulfes *• :
43. The velocities of the red and violet
in air, are, by the above eftimation, as 78
and 77 -f* ; and the intervals of their fits are,
by experiment J, as 100 and 63 : from
whence, by the canon now laid down, the
velocity of the ethereal pulfes is found to
be. to that of red light, as 79763 to 78000,
. - As
* Let C denote the celerity of the ethereal pulfes, V the
velocity of red light, and <v that of violet, I and i the in¬
tervals of their fits, and D the perpendicular diftance of two
fucceeding pulfes : it is plain, from the nature of the hypo¬
thecs, that I is to D as V to C — V, and again, D to i as
C — <v to <v ; therefore, ex tequo, I is to i as CV — Y<v to
Qqj — ; from which arifes the equation j Ty
c~ i x v—, x vl
•f In the celeftia! medium they are Iefs, [No 40.] but vpnr
yearly in the fame proportion.
% Newt, Opt, book 2. p, 1, oWervat. 14,
46 ESSAYS and OBSERVATIONS
As light moves from the fun to us, by Dn
Bradleys lateft computation *, in 8', I2f\
the pulfes of the ethereal fluid will be pro¬
pagated thro* the fame fpace in 8", i".
44. The diftance between the ethereal
pulfes, is, to 'f the interval of the fits in red,
as the difference between the velocity of the
ethereal pulfes and that of red light is to the
velocity of red light ; that interval, there¬
fore, is not much more than -Vth of the in-
terval of the fits in red, and therefore does
not much exceed ttttjj * an inch J.
, 45. The velocity of the ethereal pulfes
being determined, as above, from the inter¬
vals of the fits in the two extreme colours,
as found by experiment, the intervals of the
fits in the fix intermediate rays may be calcu¬
lated from theory; for the interval in any one
colour mail be, to that in red, as a produdl
under the velocity of the given colour apd
the excefs of the velocity of the ethereal
pulfes above that of red, is to a product
under the velocity of red and the excefs of
the
* See Fames Abridg. tranfadu vol. vi, p. 157.
4 See note # to foregoing page.
X See the table of the thicknefs of coloured plates ia
Newt. Opt. part 2, book 2 .
PHYSICAL and LITERARY. 4 1
the velocity of the ethereal pulfes above that
of the given colour: but, even upon the fup-
pofition of the truth of our theory, an exadt
coincidence between calculation and experi¬
ment is not to be expected till the velocities
of the rays be more accurately determined.
46. Upon the hypothefis of the different
velocities of different colours, we may under-
ftand, at lead: in general, whence it is, that
the intervals of the fits may bear a propor¬
tion fome way related to the fpaces* occu¬
pied by the feveral colours in the fpedxum 5
an analogy otherways very unaccountable!
Since, from the velocities of the feveral rays
upon which the intervals of the feveral fits
depend, arife likeways their feveral degrees of
refrangibility, which determine the fpace
occupied by each in the fpedirum*
And thus likeways we may conceive, how
the different rays are qualified to produce
different fenfations in the mind : for, having
different degrees of impulfive force, they
may caufe vibrations of different magnitude
or velocity in the optic nerve ; by which,
according
* Compare Ne<wt% Opt, b. i, part 2. prop. 3.. with baL
part 3. prop, 16th.
48 ESSAYS and OBSERVATIONS
according to the laws of our conftitution, the
ideas of different colours may be excited :'h in
like manner as the ideas of different tones
arife from different vibrations of the air com¬
municated to the auditory-organ. It has
been faid, That the different fenfations ex¬
cited in the mind cannot arife from the dif-
' f v
ferent force of the particles of light; fince the
colour of homogeneal rays is not altered
by paffing thro’ different media , tho’ theif
velocity be thereby always increafed or di-
minifhed But it ought to be confidered,
that every ray, as it muff pafs at iaft thro5
the humours of the eye in order to vifion,
falls upon the retina with one given velocity*
whatever number of refractions it has pre-
vioufly undergone : for the velocity of any
ray in any one medium being, to its velocity in'
any other medium , in a con Rant proportion,
viz. the inverfe of the fines of incidence and
refraction, when a ray paffes from the one
into the other; it is manifest, that each ray
muii have a certain determined velocity in
any given medium , which cannot be either
increafed or diminifhed by making the ray
* Newton* s Optics, query 13.
+ Mujfchenbroeck, Eleraenta Phyfices, § 11 6s.
PHYSICAL AKTD LITERARY* 4$
jbafs previoufly thro’ any number of tranfpa-*
rent bodies any how difpofed*.
It is impoffible therefore to know, whe¬
ther an alteration of the fwiftnefs, with
which a hotnogeneai ray ftrikes the retina ,
would alter its colour • I mean the Fenfation
of colour produced by it in the mind : fince
it is impoffible to alter, at pleafure, the
denfity of that fluid which determines its
final velocity.
One may diftinguifh two different effe&s
of the refractive power on the rays of light,
*viz. the change of direction and change of
velocity. Sir Ifaac Newton has proved with
refpeCt to the firft, That it is different in the
differently-coloured rays, and of a determined
degree in each i he has further proved. That
refradion, confidered in its firft effed, does
not change the colour of any fimple ray»
But it appears, from what we have now faid,
Tnat none of his experiments prove the
Vol. IL G immutability
* Here it is proper to obferve, that the hypothecs which
fuppoies the intervals of the fits to be determined by the ve¬
locity of the ray, agrees well with a remarkable obfervation
of Sir Ifaac Newton (Optics, b„ ii. part. i. obferv. 21.):
*1)1%,. That thefe intervals in any medium, at a given angle of
Jncidence, are of a given magnitude, without regard to eb«
denfity of the furrounding, medium*
go ESSAYS and:OBSERYATIONS
immutability of Ample rays by the fecond
effedts of refraction.
. 47. As it is of great confequence in philo-
fophy to diftinguifh between facts and hypo-
thefes, however plaulible 5 it ought to be ob-
ferved, that the various refrangibility, reflexi¬
bility, and inflexibility of the feveral colours,
and their alternate difpofltions at equal inter¬
vals to be reflected and tranfmitted, which
are the whole ground- work of xhz.Newto*
nian fyftem, are to be confidered as certain
fa 6ts deduced from experiment: but whether
the velocities of the different rays are exadtly
equal, or different in the manner now de-
fcribed, is no more than probable conjecture;,
and, tho’ this point fhould be decided by :a
method propofed afterwards, it would ffilt
continue uncertain, whether the fits of re-'
flexion and tranfmiffion are oecafioned by an
alternate acceleration and retardation of the
motion of light, or in fome other manner
x
* For infbnce, it might be fuppofed, that every particle
of light has two contrary poles, like a load-ftone ; the one
of which is attra&ed by the parts of bodies, and the other
repelled ; and that, befides their uniform rectilineal motion/
the particles of differently-coloured rays revolve in different
periods round their center/ for thus, their friendly and un¬
friendly
I
PHYSICAL and LITERARY. st
And, after all, it is no more than probable
conjecture, that fuch an alternate accelera¬
tion and retardation is brought about by the
influence of pulfes excited in the ethereal
medium : nay there are fome circumflances
*r
in thefe phenomena that feem hardly intelli¬
gible by that hypothefls alone ; as, why the
intervals of the fits are lefs ® in denfer
mediums, ; and why they increafe fo fall: and
in fo intricate a proportion, according to the
obliquity •f* of incidence.
48. According to Dr. Bradley s beautiful
theory of the aberration of light, the ftars
aopear to be removed from their true places
to a certain diftance, by the proportion
which the velocity of the earth bears to the
velocity of light : It is plain therefore, that,
on our hypothefls, a ftar muft have a diffe¬
rent apparent place for every different colour;
that is, its apparent difk muft be extended
by the aberration into a longitudinal form
refembling the prifmatic fpeftrum, having
its
friendly poles being alternately turned towards the furfaces
of bodies, they might be alternately difpofed to reflexion
and tranfmiflion ; and that at different intervals, in pro¬
portion to the periods of their rotation.
* Newt. Optics, b. 2. part 3. prop. 17.
-f Prop. 15. ibidem.
J2 ESSAYS AND OBSERVATIONS
its red extremity neared: to its true place. lr\
the ftars fituated near the pole of the ecli¬
ptic, its length ihould continue always the
fame, tho5 diredled along all the different
fecondar’es of the ecliptic in the courfe of
a year : but* in thole which lye in or near
the plane of the ecliptic, it fbould be
greateft at the limits of the eaftern and
weftern aberrations ; the ftar recovering its
colour and figure when the true and mean
places coincide. But, there is no hope of
difcovering, whether our hypothefis be true
or falfe, by this confequence of it 5 for the
greateft length of the dilated difk, being, to
the whole aberration, as the difference of
the velocity of red and violet to the mean
velocity of light, /„ e. as 1 to 77 nearly,
(N° 39.) cannot much exceed one fourth
part of a fecond ; for the greateft aberration
is but about twenty fecqnds.
49. The time 'which the extreme violet
takes to move thro5 any fpace muft be, tq
that which the red takes, as 78 to 77. If
Jupiter be fuppqfed in a quadrate afpeft with
the fun, in which cafe the eclipfes of his
fate! lites are moft commodioufly obferved,
his diftance from the earth being nearly equal
to
PHYSICAL and LITERARY. 53
to his diftance from the fun ; light takes
about forty one minutes of time in paffing
from him to the earth : therefore the laft
violet light which a fatellite refledfs, before its
total immerfion into the fhadow of Jupiter ,
ought to continue to affedt the eye for a 77th
part of 41', 01*32", after the red reflected
at the fame time is gone : that is, A fatellite*
feen from the earth, ought to change its
colour above half a minute before its total
immerfion from white to a livid greenifh
colour, thence into blue, and at laft evanifh
in violet. I need fcarcely obferve, that the
fame phenomenon fhould take place in the
time of emerfion, by a contrary fucceffion
of colours, beginning with red and ending in
white.
50. If this phenomenon fhould be adtually
perceived by aftronomers, we fhall have a
fufficient diredt proof of the different velo¬
cities of the coloured rays ; for I fee not to
wnat other caufe the phenomenon could be
rationally afcribed : If it be not, we may
conclude that rays of all colours are emitted
and reflected with one common velocity.
SECT,
54
ESSAYS and OBSERVATIONS
SEC T. VII.
\ -■ ■
On the Imperfediion of our Knowledge con¬
cerning the Inflexions oj Light .
51. Sir Ifaac Newton went a very confi-
derable length in examining the inflexions of
light, as well as its reflexions and refractions ;
but did not bring his inquiry on this head to
a conclufion. He tells us, that he intended
once, if other bufinefs had not called him
off, to have made more experiments; not for
confirming himfelf in preconceived opinions,
as many do ; but for difcovering the true
manner in which light is infleCted, for pro¬
ducing the coloured fringes with black lines
between them. He adds, however, fome
queries which contain hints of what he
had gathered on this fubjed from his own
observations, viz, that the rays of light differ
according to their colour in their degree's of
flexibility, and that they are bent feveral
times backwards and forwards with a fer-
pentine motion in paffing by the (harp edges
of bodies : thefe thoughts he threw out “in
ct order to incite others to a further fearch
But,
v . Opt, p. 313. fee the firft two or three queries.,
1
1
PHYSICAL and. LITERARY. 55
But, fo far have his intentions been difap-
pointed hitherto, that few phyfical writers
feem to comprehend 'diftindtly the hints
which he has left concerning the manner of
inflexions and none, as far as I know, has
advanced
* When any opaque body is held at the didance of three
or four inches from the eye, fo that a part of fome more
» i 1 * - .
Aidant luminous objeft, fuch as the window or the flame of
a candle, may be feen by rays paffing near its edge : If
Mother opaque bddf, nearer to the eye, be brought acrofid
from the oppofite-Yide ; the edge of the firft body will feerri
td fwell outwards -and meet the latter, and, in doing fo, will-
intercept a portion of the luminous object that was feen
before. - '
1m:
*jThls phenomenon has been-rafhly afcribed to the inflexion
of light, by fuch as 'underflood not thoroughly the nature of
inflexion, nor obferved accurately the cifcumdances of the
& rr ■ ' - id r, ' . e;:;
? T ' r f ^
Let AB reprefent the luminous objefl. (Tab. iii. Fig. 5.)
to which the fight is directed, CD the more diftant opaque
body, GH the nearer, and EF the diameter of the pupil;
join ED, FD, EG, FG, and produce them till they meet
AB in K, N, M and Li It is plain, that the parts AN,
MB of the luminous object cannot be feen. But, taking any
point a between N and K, and drawing FDd ; fince the
portion dY of the pupil i-s filled with light flowing from
that point, it mud be vifible : any point b between a
and K mud fill f F a greater portion of the pupil, and
therefore mud appear brighter. Again, any point c between
l and K mud appear brighter than b becaufe it fills a
greater portion gF with light. The point K itfelf, and every
sther point in the fpace KL, muft appear with compleat
luitrs 5
56 ESSAYS and OBSERVATIONS
advanced one ftep beyond them. It is fur-
prizing, that, before Sir lfaac Newton, the
world continued fo long entirely ignorant of
the true theory of light and colours ; and it
is no lefs io, that, fince he quitted the fub-
je<5t, no further difcovery of any moment has
vet been made amongft all the philofophical
Societies in Europe . i
52. Many
f » f
> • ? vf; n S
luflre; fmce they fend entire pencils of rays EKF, ELF td
the eye : and the vifible brightnefs of every point from L
towards M muft decreafe gradually as from K to N : i. e*
The lpaces KN, LM will appear as dim fhadowy borders or
fringes adjacent to the edges of the opaque bodies. When,
the edge G is brought to touch the right line KF, the pe~
mumbra’s unite ; and, as foon a° it reaches NDF, the above
fleenomenon begins : for it cannot pafs that right line without
meeting feme line aDd drawn from a point between N and
K, and, by intercepting all its rays that fell upon the pupil;
render it in vifible. In advancing gradually to the line KDE,
It will meet other lines bDf9 cDg, ire- and therefore render
the points b , c , &c. from N to K fucceffively invifible ;
and therefore the edge of the 6xed opaque body CD muft
feem to fwell outwards, and cover the whole fpace NK,
while GH by its motion covers MIC. When GH is put to
a greater diftance from the eye, CD continuing fixed j the
fpace OP to be palled over for intercepting NK is lefs j and
therefore, with an equal motion of GH, the apparent fwel-
ling of CD muft be quicker ; which is found true by expe¬
rience If ML reprefents a luminous objedt, and REFQ_
any plane expofed to its light; the fpace FQjvill be entirely
fhaded
PHYSICAL a£jd LITERARY. 57
52. Many ingenious men have bellowed
infinite thought and labour on the more
complex and aftonifhing phenomena of
Nature, without arriving at any certain or
definite difcoveries 5 filch as earthquakes,
thunder and other meteors, magnetifm,
electricity, vegetation, fermentation and
other chemical operations : and the fubtilty
of thofe matters will probably continue to
elude the fearch of lateft pofterity. But, iri
the Ampler, Readier, and more regular fub-
jedts, fuch as light and colours, which are
capable of accurate menfuration and mathe¬
matical reafoning, a fagacious and induflri-
r * > at
ous obferver can hardly fail of making fomd
progrefs ; efpecially in a branch of the in¬
quiry which is already pufhed to a confider-
able length. Difcoveries of this kind are
capable of a particular fort of proof which
is very beautiful and convincing, from the
exaft coincidence of the computed effects
Vol. II, II with
fbaded from the rays, and the fpace FE will be occupied
by a -penumbra gradually darker bom E to F : Let now GH
continue fixed, and CD move parallel to the plane EF §
and, as foon as it is paffes the line LF, it is evident, that the
fhadow QF will feem to fwell outwards, and when CD
reaches ME fo as to cover with its fhadow the fpace RE*
Of by its extenfion will cover FE. This is found to held
V
true likeways by experiment*
fit ESSAYS and OBSERVATIONS
with the real ones, as to quantity. Many
inftances of this occur in Sir IJaac New¬
ton s writings, and in all mathematical philo-
fophy : fuch as the calculation of the
moon's irregularities of the tides ; of the
preceffion of the equinoxes ; of the refi-
ftance of fluids ; and, in optics, his compu¬
tation of the dimenflons of the rainbow
of the aberration of colours ; of the inter¬
vals of the fits of reflexion and tranfmif-
fion ; and of the coloured rings refled ed
by thick tranfparent Jpeculums*
What further I have to offer concerning
light and colours, confifting chiefly of doubts,
difficulties or loofe conjedures, fhall be pro-
pofed under the form of queries.
SE C T,
PHYSICAL and LITERARY. 59
SECT. VIII.
* «
Queries , confuting of Doubts , Difficulties , and
Conjectures , concerning Lights Colours , and
coloured Bodies .
Query I. Are not the rays, emitted by
all forts of luminous bodies, fimilar to thofe
of the fun, both as to colour and degrees of
refrangibility ? And, do not luminous bo¬
dies differ from one another only according
to the colours which they emit moft plenti¬
fully, in like manner as opaque bodies are
diftinguifned by the colours of incident light
which they refled: in greatelt abundance ?
( See N° 24, 25, 26, 27, 28, and 29.) But,
to make our induction fufficiently ftrorig,
ought not experiments to be made with the
lights of a greater variety of bodies? And
would it not further conduce to the illuftra-
tion of this queftion to form, by Sir Jfaac s
method a beam of folar light, confiding
of luch colours and in fuch proportions as
were feen in the lights of falls and burning:
fpirits ; and then to obferve in it the appear¬
ance
* Newt. Opt. book 1. part 2. prop, 11.
%
ESSAYS and OBSERVATIONS
ance of coloured bodies ? Further, are not
the Intervals of the fits, in rays of any one
colour, the fame in the fame medium , from
whatever luminous body they are emitted ?
For, if thefe intervals were different, would
there not be changes in the colours of bodies
not to be accounted for by the compofitions of
the lights with which they are illuminated* ?
Quer. II. Do not all luminous bodies,
the rnoft languid as well as mod bright, emit
their lights of any one colour with one de¬
terminate velocity 5 lince it is found by ex¬
perience that they are all equally refradted by
the fame medium t And therefore, does not
the different fplendor of luminous bodies
*
proceed wholly from the different denfity of
their light at equal diftances ? And is not
this confirmed by the equality of Bradley s
aberration of light in fixed ftars of all ma g-
nitrides ? If this be fo, the comparative
ftrength of different lights, fuch as of the
inn, moon, a candle, &c. may be ealily
pfti mated by finding the greateft diftances to
which the fame opaque body is vifible when
illuminated by each of them, or the limits be-
yond
* See Art.
t Eem*** Abridg. of franfaft. yol. 6. p. 158.
PHYSICAL and LITERARY. 6x
yond which it is invifible to a given eye ;
for the aenfities of the incident lights are
nearly as the fquares of the diftances of thefe
limits from, the objeCt *. Does not all light
move with the fame velocity after reflexion
as before ; fince the angle of reflexion is al¬
ways equal to the angle of incidence ? The
exception, made by fome, of electrical light
is founded on no lefs a miftake than con¬
founding the luminous body with its light
But, the befl: proof of this propofition is from
the coincidence of the computations of the
velocity of light, from the equation of the
eclipfes of Jupiter $ fatellites and the aber¬
ration of the fixed ftars J.
* Let A and a (Tab. iii. fig% 6.) denote the fame or two
equal bodies of the fame colour illuminated with different
lights, and B, b , the limits. As we fuppofe the light re¬
ceived by the eye, at thefe points, is juft fufhcient to affedt
it fenlibly and no more, the two lights at thefe different di¬
ftances muft be nearly of the fame denfity ; taking therefore
in AB a line A$ equal to ab, the denftty of the light at muft
be, to The denlity of the light, at b, nearly asABi to A bx ;
and, it is evident, that thefe denftties, at equal diftances,
muft be as the whole quantities of light reflected ; and thefe
again very nearly as the whole quantities of light incident.
t Mujjchenbroeck' s Elementa Phyfices, late edition, in hi^
chapter on electricity.
% Earnest Tranfadt. vol. vi. &c.
t *
6a ESSAYS and OBSERVATIONS
QtJER. III. Is light emitted with the fame
velocity, in whatever medium the luminous
body be placed ? Or, is it not rather emitted
with greater velocity in denfer med'ums , and
that in proportion to their refractive powers?
The fame argument Rom whence we
gather in general the equal velocity of light
emitted by all forts of luminous bodies, feems
to prove the truth of the latter fuppofition.
For, fince rays of any one colour, from the
fun and a candle, for inftance, are equally
refraded by a furface of glafs or water, we
may conclude, that their velocities in air are
equal. Wherefore, if the denfitv of the
fun's atmofphere, contiguous to his furface,
be different from the denfity of our lower
air, as may be fafely prefumed, his rays
muff have been emitted with more or lefs
velocity than that of the candle 5 otherways,
they could not have the fame velocity after¬
wards in any common medium : for, the ve¬
locity with which any ray is emitted, is, by
the laves of refradion, to its velocity in any
eiven medium , as the fine of refraction to the
ppe of incidence, when a ray paffes from
the
f i
PHYSICAL and LITERARY;
the medium of e million into the given
medium .
4
Quer. IV, If the atmofphere is not much
warmed by the pafiage of the fun's light
thro’ it, but chiefly by its contact with the
heated furface of the globe, as we Ah e wed
above (N° 15.); may we not hence give
one very Ample and plaufible reafon, why
it is coldeft in all climates on the tops of
very high mountains 3 namely, becaufe they
are removed to the greateft diflance from the-
general furface of the earth ? For it is well-
known, that a fluid heated by its contadt
with a folid body decreafes in heat, in fome
inverfe proportion to the diftance from the
body. But, to have this queftion fully de¬
termined, the temperature of the air in the
valley and on the mountain -top mud be ob-
ferved every hour both night and day, and
carefully compared together.
Quer. V. From what has been laid down
in Sedt ii. concerning the manner of the
adlion of light in heating bodies, is it not
reafonable to fuppofe that the heat produced
by a given number of rays, in an opaque
body of a given magnitude, mud be greater
when
5 4 ESSAYS and OBSERVATIONS
when the rays are more inclined to one
another, than when they are lefs fo ? For
the dire&ion of the vibrations, railed by
the adtion of the light, whether in the
colorific particles or thofe of an inferior
order, will more interfere with one another 3
from whence the inteftine (hocks and colli-
fions mu ft increafe : befides this, the colori¬
fic particles of opaque bodies being dif-
pofed in various fituations, perhaps, upon
the whole, the rays will fall more diredtly
on each, the more they are inclined to one
another. Is not this the reafon of what has
been remarked by philofophers^j*, That
the heat of the fun’s light, colledled into a
cone, increafes in approaching the focus in a
much highef proportion than according to
its denfity ? That the difference of the
angle, in which the rays fall on any particle
of a given magnitude placed at different
diftances from the focus, is but final], is no
proof that the phenomenon cannot be afcribed
to it 3 fince we know not in what high
proportion one or both the circumftances
now mentioned may operate. However,
that
* Boerhaawe , Element, chemic. de igne.
t Muffcbenbr . Elementa Plryfices, § 1040,
PHYSICAL and LITERARY, 65
that it proceeds not from any unknown
action of the rays upon one another, as has
been infinuated*', is evident from this, that
each particular ray, after pafling thro’ the
focus, preferves its- own colour and its
Own direction, in the fame manner as if it
were alone.
Quer. VI. May it not be inferred, that
the component parts of opaque bodies are
greater than thole of tranfparent ones, as
theory requires -j^, from this Ample obferva-
tion, that the former, fitch as metals, ftones^
woods, &c. when broken tranfverfely, {hew
a vifible roughnefs and inequality at the
fradture , whereas the latter, fuch as glafs,
chryftal, gems, ice7 &c, appear as fmooth*
almoflq as when they are polifhed ?
Quer. VII. Do not Newton's experiments
with the ifland and rock chryftal fufficiently
* ■ % - * *•
prove, that the rays of light have different
permanent properties in their different tides,
relative to thefe two bodies ? Muft we not
therefore conceive each particle of light to
preferve its pofition invariably while it moves
forward, at leaf! fo as not to revolve round
Vol. II. I its
* MuJfchenbroecJt s Eiementa phyfices, $ 1040.
f Opt. Book 2. part 3. prop! 4^
66 ESSAYS and OBSERVATIONS
its center perpendicularly to the direction of
its motion? Would it not be proper to try
how light is infledled in paffing clofely by
the feveral angles and fides of thefe foffils ?
Qijek. VIII. Is it not poffible to prove by
experiment what Sir Ifaac Newton takes for
granted as a reafonable fuppofition, that thin
tranfparent plates, of any uniform colour,
divided into fmaller fragments, would com-
pofe a powder of like colour ? And would
not this tend to ftrengthen the analogy be¬
tween the colours of fuch plates and thofe
of natural bodies ? For this purpofe, I have
tried to freeze foap-bubbles ; but could ne¬
ver make any Hand till they were turned to
ice, except fuch as were too thick to have
lively colours : however, I doubt not, but,
with due care, the thing might be done ;
efpecially, if the foap- water, inftead of be¬
ing blown with a pipe into bubbles, were
drawn out into a plain plate upon any wooden
or metalline frame : for, the fides of a plain
furface bearing a greater proportion to its
area, than a bafe of a fpherical fegment to
its furface, the froft would be fooner com¬
municated-
Newton' s Opt. book 2. part 3. prop.- 5.
PHYSICAL and LITERARY. 6 7
I
municated to the whole water in the former
cafe than in the latter. There is this advan-
tage too in ufing a plain fur face of foap- wa¬
ter, that, before it freezes, the obferver
may draw out any particular colour or feries
of colours, which he chufes, to a greater
breadth, by ftroaking it along with a wet
finger. For this reafon, amongft others,
I have found it a more convenient fubjedt for
examining the various orders of colours, than
fpherical bubbles adhering to a plane. Per¬
haps, melted rofin might be drawn out into
a thin-coloured plate before it hardens 5 for
I have often blown it into bubbles with a to¬
bacco-pipe till it became coloured. I know no
other ways in which the various orders of co-
lours can be prcferved for deliberate infpedion,
but either in a frozen plate of water or rofin,
or in the permanent fcoria that appear on
heated metals. I have counted, on the fide
of a clean-polifhed copper tea-kettle, the
fix firft orders of colours diftindtly and regu¬
larly ranged in the fame fucceffion in which
they appear in the foap- bubbles 3 the firft or¬
der being formed on that part of the kettle
that had been leaft heated,
Qjjer,
68 ESSAYS and OBSERVATIONS
■Quer. IX. What eife is the inflexion of
light towards the fine edges of bodies than a
particular cafe of refraction, in which the
rays, after being bent by the attractive
power, are carried beyond the refracting
furface, and mifs 'entring it, becaufe of its
fmall extent ? For, if the furface of the
edge be produced, it will meet the infieCted
rays ; and thus the inflexion will become
properly refraction. And, in like manner,
we may conflder the inflexion of light off
from the edges of bodies, as a fpecies of re¬
flexion.
Quer. X. Is it not impoflible that an ani-
fnal can fee, if the diameter of its eye be
much lets than the interval between the fits
of tranfmiffion and reflexion in water, that
is, than -rh of an inch ?
Quer. XL There are many experiments
which fhew that a yellow and blue ray
mixed, make a green one ; a yellow and
blue powder, a green powder; and a mixture
of rays or paints of all the prifmatic colours,
a white ray or paint : Now, do not the fame
experiments equally demon ftr ate, that the
lap of green is a confufiqn or mixture of the
ideas
PHYSICAL and LITERARY. 69
Ideas of yellow and blue ; the idea of white,
a mixture of the ideas of all the colours ; and,
in general, the ideas of all compound colours,
a mixture of the ideas of their eonftituents ?
In the experiments which Sir Ifaac Newton
performed with the toothed inftrument, the
component colours are not, indeed, prefented
to the eye all at once ; yet they follow one
another in fo rapid a fucceffion, that their
refpedtive imprefiions remain in the eye till
they are renewed, and therefore they muft
affedt the mind all at once If a piece of
paper
* It is in this manner that philosophers explain (Newt,
(Opt. Quer. 1 6.) the appearance of a fiery circle, which is
made by a burning body whirled about fwiftly. We fhalj
here give an account of fome other phenomena that flow from
the fame principle.
If a white rod be moved rapidly backwards and forwards
with an angular motion, the whole circular fpace which it
runs over will appear whitifh ; but not equally fo, being
fainted and mod dilute in the middle, and brighter towards
the two Tides, which feem to be didinctly terminated with
two white rods interfe&ing each other in the center of ro¬
tation. (See Tab. iii. Fig 7.)
The total impredion made upon the eye by equal fmali
parts of the fedlor mud be, as the quantity of light emitted
from it and the frequency of the returns of the rod to it ;
u s. inverfely, as the time between the returns of the rod,
i i ’ ; • * v
Let
fo ESSAYS AND OBSERVATIONS
paper be daubed all over with (mail dots of
blue and yellow, it will appear green to an eye
which is placed at too great a diftanee to di-
ftinguifh
Let ABC reprefent the circular fedor, and DC a line bi-
feding it ; the rod always returns to DC after the time of
of one vibration ; and, to any other line EC between DC
and AC or AB, the mean time of it? return is the fame ; for^
it alternately returns in twice the time of defcribing AE,
and twice the time of defcribing EB; fo that two fuc-
ceeding intervals of its returns are equal to the time of two
vibrations : but the intervals of the returns to the lines AC
&r CB are manifeflly equal to the time of two entire vibra¬
tions. The brightnefs of the fedor therefore in DC, -or any
♦
line between DC and AB or BC, mull; be fimply as the quan¬
tity of light emitted from equal fmail portions of the fedor ;
that is, in the inverfe proportion of the velocities of the rod
when in thefe lines. It is plain from this, that the fedor
mult be incomparably brighter in AC and BC, where it relts,
than any where elfe, notwithftanding that the intervals of
return thither are double ; that is, it will appear to be
bounded diltindly with a white rod on each fide.
If the rod be agitated with fmail and quick vibrations of
its own, by flicking it againlt fome folid body immediately
before it is hurried backwards and forwards with the angular
motion, the fedor appears divided, at equal intervals, by a
great many dillind rods, almoft as bright as the two lateral
ones (Tab. iii. Fig. 8.) refembling the (pokes of a fpread fan.
The reafon of which curious phenomenon is plainly this j that
its angular motion, being alternately in the fame and in a
contrary diredion to its particular vibrations, is alternately-
accelerated and retarded or ftopt. In the interval, where it is
accelerated, the fedor mu ft appear very dilute i and, where .
PHYSICAL and LITERARY, jt
flinguifh the feparate points. In whatever
manner fenfation be performed, it is certain*
that the organs which receive the firft im-
pulfe from external objedts cannot convey to
us any ideas, if they, or the imprefiions made
by them, be lets than of a certain definite
magnitude. A number of things feparately
intangible, if joined together, may be felt by
the touch : A certain number of invisible
points become fufficient to affect the fight
by their united rays ; and a certain number
of founds too fmall to be heard feparately, at
laft form an audible found
it is greatly retarded or brought to reft, muft appear very
luminous or divided by white rods, for the fame reafon that
•'t r* • '
they appear at the Tides.
* Some Sceptics have difputed againft the endJefs divift-
bility of quantity, becaufe the imagination foon arrives at 3
minimum ; alledging from thence, that our idea of extenfion
involves the notion of indivisibles, and is as it were com¬
pounded of them. Nothing corporeal can be imagined or.
conceived at all which is not conceived as feen, handled , or
otherways fenftbly perceived. Imaginative ideas are nothin??
elfe than tranfcripts or images of fenfations, and therefore
muft be limited by the fame bounds and in the fame manner
as fenfation. Now the minimum fenjihile is rather in all cafes
a confufed, indiftindt and uncertain tranfition from per¬
ceivable to not perceivable , than the clear perception of a
point indivifible in magnitude ; for its magnitude depends
72 ESSAYS AND OBSERVATIONS
Quer. XII. Since bodies derive their
colours from the original and immutable
qualities of thofe rays which they refled:
moft copioufly, ought they not to appear of
the fame colour, whether viewed at the
gfeateft or leaf!: distances ? Whence is it
therefore, that the planets whofe foiid parts
are probably covered with vegetables, and
mufl therefore refted a great fuperiority of
green
on the luffre of the objedl. That nothing can be conceived
Or imagined which is lefs than a certain bulk, is no more ari
argument againft the endlefs divifibility of quantity, than
that nothing can be felt or feen below that fize ; which, it is
evident, from every magnifying glafs and from every diffe¬
rent diflance of an objedt, depends not at all on the confti?
tution of the thing perceived, but on that of the perceiver, or
the means and circumftances of his perception.
Nor, tho’ it were granted that the mini?num < vifilile is di~
flin&ly feen as an indivifible point, would it follow, that
the idea of extenfion, received by fight, i* made up of the
Ideas of indivifibles; for we receive the idea of extenfion
by that motion of the eye which is neceffary to diredt its
axis to different objedts or parts of an object : and, it is
well known, that the generation of quantity by motion is
preferred by the beft writers, for this very reafon, that it
neceffarily excludes the notion of indivifibles. It fhould be
remembered likeways, that a vifible objedt is not divided by
the eye into a number of contiguous minima <vifihilia ; for, to
whatever mathematical point in the objedt the eye is di-
redted, a miiiimum <vijibile may be feen there by means of &■
certain portion of the objedt immediately furrounding k.
I
PHYSICAL Aftrf LITERARY.' 73
\
green rays, appear almoft intirely white
when viewed from the earth ? May not this
be accounted for, in the fame manner as the
change of colour obfervable in earthly ob-
]eds feen thro’ a great trad: of the atmo-
fphere ? A mountain covered with the
frefheft verdure, at the diftance of twelve or
fifteen miles, looks blueifh ; and at twenty
or thirty, efpecially if the air be thickened,
degenerates into a dim white, fo that one
can hardly diftinguifh it from the clouds that
fkirt the horizon. With refped to the pri¬
mary planets, it may be like ways anfwered,
that perhaps we fee them chiefly by light
refleded from the air and vapours that fur-
round them,,
* * *
Quer. XIII. Why is it fo hard to diftin¬
guifh green bodies from blue by candle¬
light ?
Quer. XIV. Whence proceeds the blue-
nels of the fky ? Since it is certain that no
body affumes any particular colour, but be-
caufe it refleds one fort of rays more abun¬
dantly than the reft , and fince it cannot be
fuppofed that the conftituent parts of pure
air are grofs enough to feparate any colours
of themfelves ; muft we not conclude, with
Vol, II, K Sir
74 ESSAYS and OBSERVATIONS
Sir Ifaac Newton that the violet and blue-
<
making rays are refledted more abundantly
than the reft, by the finer vapours diffufed
thro" the atmofphere whofe parts are not
big enough to give them the appearance of
vifibie opaque clouds ? Do not thofe who
fay that the ethereal blue proceeds from
the mixture of the fun’s white light refledt-
ed faintly by the atmofphere with the perfect
blacknefs of the celeftial fpace behind, re¬
vive, without any neceflity, the antient con-
fufed notion, that all colours may be formed
by certain compofitions of light and fhade ?
Altho" the atmofphere refledts more blue rays
than what go to the formation of perfedt
white, it is eafy to conceive how coloured
bodies, illuminated by it, may not be fenfi-
bly tindtured with blue. Let us fuppofe,
that the atmofphere refledts ~ more of blue
rays than of the other colours, and that ver¬
milion refledls of the red rays incident '
upon it, and — of every other colour;
then, it is dear, that the red rays, refledted
by the vermilion, will ftill exceed the blue
refledted by it, as 19 exceeds 1 fo
that
* Opt. book 2. part gv prop. 7.
•J- Nature difplayed, vol. iv. And Mu/chen . Phyf. § 1403..
PHYSICAL and LITERARY. 75
that the purity of its red colour will not be
fenfibly impaired. But, to (hew that, in
proper circumftances, the blueiffi colour of
Iky-light may be feen on bodies illuminated
by it, as it is objected fliouid always hap¬
pen*; expofe to the fun -beams, on a clear
cloudlefs day, a fheet of white paper, and
place on it any opaque body ; you will per¬
ceive that the fpace of the fhadow, which is
illuminated only by the Iky, appears remark¬
ably blueiffi, compared with the reft of the
paper which receives the fun’s aired: rays. If
certain white and black paints mixed together
produce blue, it is becaufe the black is not
perfed (hade, but a dark blue or purple ‘f*
Any mixture of whitenefs and true black
can only form a fainter white or grey, which
has no more affinity with blue than with red
or any other colour,
Quer. XV. Is not the opinion which Sir
Jfaac Newton feems to have had ||, and, fince
him, the generality of philofophers, con¬
cerning the caufe of the various colours re-
fleded
* Mu/chen. Phyf. § 1403.
Ibid. § 1172.
\ Newt. Opt. book 2. part 3. prop. 7.
J Opt. book 2. part 3. prop. 5. near the end.
ESSAYS and OBSERVATIONS
fleCted by the clouds at fun-rifing and fetting,
liable to great difficulties ? For, why ffiould
the particles of the clouds become, at that
particular time and never at any other, of
fuch magnitude as to feparate thefe colours ?
And why are they rarely, if ever, feen tin¬
ctured with blue and green, as well as red,
orange and yellow ? Is it not more credi¬
ble that the reparation of rays is made in paf-
ling thro' the horizontal atmofphere ? and
that the clouds only refect and tranfmit the
fun’s light, as any half transparent coiourlefs
body would do in their place ? For, fince the
atmofphere, as was faid in the laft query,
reflects a greater quantity of blue and violet
rays than of the reft, the fun’s light, tranf-
mitted thro’ it, ought to draw towards yel¬
low, orange, or red ; efpecially when it
paffes thro’ the greateft trad: of air : accord¬
ingly, every one muft have remarked, that the
fun’s horizontal light is fometimes fo deeply
tinCtured, that objects direCtly illuminated by
it appear of a high orange or even red 3 at
that inftant, is it any wonder that the colour-
lefs clouds refled the fame rays in a more
bright and lively manner ? It is obfervable,
that the clouds do not commonly a ffume .
their
PHYSICAL and LITERARY. 77
their brighter dyes till the fun is fome mi¬
nutes fet ; and that they pafs from yellow to
a flaming golden colour ; and thence, by
degrees, to red 5 which turns deeper and
deeper, tho’ fainter, till the fun leaves them
altogether. Now, it is plain, that the clouds,
at that time, receive the fun's light thro’ a
much longer tradl of air than we do at
the inftant of fetting, perhaps by the diffe¬
rence of a hundred miles or more ; as may be
computed from their height or the duration
of their colours. Is it not, therefore, na¬
tural to imagine, that, as the fun’s light be¬
comes always fome what yellowifh or orange
in paffing thro’ the depth of the atmofphere
horizontally, it ought to incline more and
more from orange towards red, by paffing
thro’ a Hill greater length of air 5 fo that the
clouds, according to their different altitude,
may affume all the variety of colours, obfer-
ved in them at fun-rifmg and fetting, by
barely reflecting the fun’s incident light as
they receive it ? I have often obferved with
pleafure, when in Switzerland , that the
fnowy fummits of the Alps turn more and
more reddifh after fun-fet, in the fame
manner as the - clouds. What makes the
fame
73 ESSAYS and OBSERVATIONS
fame colours much more rich and copious
in the clouds, is their femi-tranfparency joined
with the obliquity of their fituation.
Does it not greatly confirm this explica¬
tion, that thefe coloured clouds immediately
refume that dark leaden hue which they re¬
ceive from the fky as foon as the fun’s diredt
rays ceafe to ftrike upon them ? For, if
their gaudy colours arofe, like thofe of the
foap-bubble, from the particular fize of their
parts, they would preferve nearly the fame
colours, tho’ much fainter, when illumi¬
nated only by the atmofphere. About the
time of fun-fet or a little after, the lower part
of the iky, to fome diftance on each fide from
the place of his fetting, feems to incline to
a faint fea-greeri, by the mixture of his
tranfmitted beams, which are then yellowiih,
with the ethereal blue : at greater diftances,
this faint green gradually changes into a red-
difh brown $ becaufe the fun’s rays, by
pafllng thro’ more air, begin to incline to
orange : and, on the oppofite fide of the
hemifphere, the colour of the horizontal
iky inclines fenfibly to purple ; becaufe his
tranfmitted light which mixes with the
azure, by paffing thro’ a (till greater length
of
PHYSICAL and LITERARY. 79
of air, becomes reddifh ; as we have faid
above.
To underftand diftindtly why the fun’s
rays, by pafiing thro’ a greater and greater
quantity of air, change by degrees from
white to yellow, thence to orange, and laftly
to red, we have only to apply to the atmo-
fphere, what Sir Jfaac fays (Book I. of his
Optics, part 2. prop. 10.) concerning the
colour of tranfparent liquors in general.
Is it not the fame coloured light of the
rifing and fetting fun which tindtures the
clouds, that, being thrown by the refradtion
of the atmofphere into the earth’s fhadow*
gives the moon fometimes, in total eclipfes,
the obfcure reddifh colour of brick? As
the rays which pafs thro’ the greateft tract of
air, become reddifh 5 thofe which pafs thro*
the lea ft, yellowifh ; and the intermediate
ones, orange: the red mu ft converge fafteff
into the fhadow 5 after them, the orange $
and laftly, the yellow : fo, that the whole
fpace of the earth’s fhadow, from the point
of the cone to about femidiameters from'
the earth, being filled with a faint light,
whofe colours verge always more to red
in approaching the earth 5 the colour of the
moon.
go ESSAYS AND OBSERVATIONS
moon, in total eclipfes, muft needs vary like-
ways, according to her diftance from the
earth at the time of obfervatidn ; and, if I
mi flake not, be always more inclined to red
at entering and leaving the fhadow, than in
the middle. Let Aftronomers determine,
whether the phenomena agree with this
theory. It is not furprizing, that this re¬
fracted light is very faint and obfcure at the
diftance of the moon ; fince its mean denfity
there, will be as much lefs than the denfity of
the light of the fetting fun, as the annular fpace
of the lower air thro' which it pafies, drawn
into the moon’s horizontal parallax, is lefs than
the area of a great circle of the earth drawn
into four times the excefs of the horizontal
refraftion of the atmofphere above the fame
parallax; that is perhaps as i to or more,
Quer. XVI. I have obferved, when at fea,
that, tho’ I prefled my body and head
firmly to a corner of the cabin, fo as to be at
reft in refpeft of every objeCt about me, the
different irregular motions of the fhip, in
rolling or pitching, were ftill difcernible by
the fight : How is this facfl to be reconciled
to optical principles ? Shall we conclude,
that the eye, by the hidden motions of the
veffel*
PHYSICAL and LITERARY. Bt
veffel, is rolled out of its due poiition ? Or,
if it retains a fixed fituation in the head, is
the perception of the (hip’s motion owing to
a vertigo in the brain, a deception of the
imagination ; or to what other caufe ?
Quer. XVII. Has not gold been reduced,
by beating, to a degree of thicknefs little
exceeding that which muft be afcribed to its
colorific parts* according to Sir Ifaac New¬
ton's theory ? But, how can it cohere into a
continuous leaf, fo as to leave no vifible
pores, unlefs there be many of its compo¬
nent particles contained in its thicknefs ?
Quer. XVIII. When one looks ftedfaft-
ly at Sirius or any bright ftar not much ele¬
vated above the horizon, its colour leems not
to be conftantiy white, but appears tinctured,
at every twinkling, alternately with red and
blue: To what is this appearance owing ?
Is not the reparation of colours by the re¬
fraction of the atmofphere too fmail to be
perceived ?
Quer. XIX. Bodies become black by
burning; becaufe they are reduced* into
very fmail parts : but, whence is it, that
Vol.II. L mod
\
* Kewt. Opt. Book iii, part 2. prop, 7.
82 ESSAYS AND OBSERVATIONS
moft bodies, when further burned to afhes,
affume a grey or whitifh colour ?
Quer, XX. Since the caufe of blacknefs
in bodies is the fmallnefs of their tranfparent
parts, which renders them incapable of re¬
flecting any colour ; how can black bodies,
folid or fluid, be at the fame time opaque ?
Can light be finally ftifled by the refraCtive
powers of the particles alone? or, ought it not
rather to make its way thro’ the body, if
there be no reflexion, without any fenfible
lofs, altliQ* the feveral rays might iffue in
various directions ? And, may it not be de¬
manded, in like manner, concerning all co¬
loured opaque bodies, How all forts of light
can be ftifled and ftopt within a body, whofe
internal parts are fitted to refleCt only one or
two colours, and tranfmit all the reft ?
Quer. XXL If the parts and pores of
pellucid bodies be much lefs than the leaft
interval between the fits of 'reflexion and
tranfmiffion ? it is plain, that rays of light,
entering a part or pore in a fit of tranfmiffion,
will not be reflected at its back furface : and
thus it may be underftood, how all rays that
enter the firft furface of a tranfparent body
continue to be tranffnitted thro’ its fubftance
PHYSICAL and LITERARY. 83
to the greateft diftances, viz, if the rays are
always put into a new fit of mojt eajy tranfr
million at entering every new pore or particle.
But is not that fuppofition contrary to what
Sir Ifaac teaches el fe where ; That the fits of
reflexion and tranfiniffion continue to return
at equal intervals, after a ray has entered a
tranfparent body, and are thus regularly pro¬
pagated to the greateft diftances^? And, if
this be true, how can the rays be tranfmitted
to any fenfible difiance, fince they muft
often arrive in fits of eafy reflexion at the
common furfaces of pores and particles ? But,
altho’ it could be underftood by the dodtrine
of the fits in light why there is no reflexion
from the interior parts of water and other
pellucid mediums 'j-, does not the redtilinear
tranfmiiilon of light thro" thefe bodies in all
directions, and confequently in all degrees of
obliquity, to their internal parts, prove, that
thefe parts, upon account of their minuteneis,
lofe their powers of refraction as well as
reflexion ? And to what known property of
light or bodies can this be attributed ?
Quer,
# Newt. Opt. Book ii. part 2. prop. \z,
•f Ibid. Book ii. part 3. prop. 4.
§4 ESSAYS and OBSERVATIONS
Quer. XXII. If the fits are produced by
an alternate acceleration and retardation of
the particles of light, fome of the particles,
which are fwift enough to be tranfmitted at
the firft furface of a tranfparent medium , muft:
overcome the reflecting power more eafily
than others 3 namely, thole that happen to
be in their point of greateft celerity or
neareft to it : Now, muft not rays that are
moving with different velocities be different¬
ly bent from their courfe, as we argued
above with refpeCt to ftmple-coloured rays,
by the fame refractive power ? Why there¬
fore is not every beam of light, homogeneai
or heterogeneal, diffufed by refraction into
innumerable rays, according to the refpe-
Ctive velocities with which they entered the
refraCting furface ? Is it a fufticient anfwer
to this query, That rays which are fartheft
from their point of greateft fwiftnefs will be
mod bent in a direction contrary to that of
refraCtion, by the reflecting power, and will
therefore only return to the direction of
iwifter rays by a greater degree of refraCtion ?
Qu e r . XX III. Sir Ijaac Newton j uftly ar¬
gues, that light muft be reflected at a diftanee
from bodies.; becaine the moft polifhed fur-
PHYSICAL and LITERARY. 85
face, being extremely rough and uneven in
, f, e , , \
refpeCt of the particles of light, would di-
fperfe them indifferently in all directions, if
they rebounded from it by ftriking: But,
will not the like difficulty ftill remain, viz*
how light can be reflected or refraCted regu¬
larly by the beft-polifhed furface, if the
power of the body proceeds from an attra¬
ction or repulfion belonging to each phyficai
point ? It might be perhaps fuppofed, that
the repulfive power produces reflexion at a
diftance fo great, in refpeCt of the inequa¬
lities that are left in polifhed bodies, that the
direction of force, refulting from their joint
action, may be very nearly perpendicular to
the general furface of the body ; and this
might tend to account for the regular refle¬
xion from the anterior furface of a denfer
medium . But, will this fuppofition fuffice
for explaining the regularity of refraction,
and of reflexion, from the pofterior furface
of a denfer medium : in both which cafes,
the light mu ft actually enter the pores of tjie
attracting body, and therefore approach
much nearer to one inequality than another $
iince the pores,* by which it enters, are cer¬
tainly much iefs than thole inequalities? In
water*
86 ESSAYS and OBSERVATIONS
*
water and other tranfparent liquors, this
muft certainly be the cafe, if their globular
particles touch one another, as is commonly
concluded from their incompreffibility : for,
as a number of fpheres laid together leave no
re&ilinear paffages between them, the tranf-
mitted light muft pafs thro" the component
particles ; and therefore the pores, by which
it enters, muft be much lefs than the wdiole
hemifpherieal furfaces of the particles which
evidently conftitute the inequalities of the ge¬
neral furface of the liquor
Qjjer. XXIV. How does light preferve
its reftilinear courfe in paffing thro’ air, cether
and other elaftic fluids ? Will not the diffi¬
culty ft ill continue, whatever fubtility or ra¬
rity is afcribed to thefe mediums ; fince the
powers from whence their elafticity arifes,
muft prevail thro’ all the free fpaces that in-
terveen their particles ? Muft we not, there¬
fore, fuppofe, that the rays of light are not
fubjedt
* We are certain, that the inequalities of a craggy rock
or rough wall are much greater than the particles of air
or their diftance from one another, by which their re¬
pul five powers are probably terminated (Newt. Princip.):
Why is found, therefore, reflected fo regularly from iuch
bodies, that the echo is faintly heard,- except at an angle of
incidence equal to the angle of reflexion 1
PHYSICAL and LITERARY. '87
fubied to'thefe repulfive powers, tho* they
oafs thro’ the fphere of their adion ? Does
not the refradion of light towards the per¬
pendicular, out of the celeftial fpaces into
air, even prove that it is attracted by the par¬
ticles of air? Would it not be extravagant
and incongruous beyond meafure, to imagine
the tether fo fubtile, in refped of light, that,
tho’ it be driven out of the way by the rays,
as air is by common projediles, it is not ca¬
pable of retarding them fenfibly in their mo¬
tion from the mod diflant fixed ftars to our
eye ? Do not thefe and many other difficul¬
ties, in the phyfical part of Optics, whofe
folution is fought for in vain from any prin¬
ciples hitherto difcovered, fhew the necef-
lity of extending our views and inlarging
our flock of principles by further experi¬
mental inquiry ? Such objedions are not to
be confidered as demonftrations of the falfe-
hood of our prefent theory ; but as proofs
of its narrownefs, partiality and imperfe-
dion.
Des Cartes, contenting himfelf with a
fuperficial and inaccurate knowledge of the
laws of impulfe, vainly dreamed, that he
had got pofleffion of the univerfal caufe
from
M ESSAYS and OBSERVATIONS
from whence all effefts in Nature are deri¬
ved ; when, in truth, he was unable to de¬
duce from them the fimpleft cafes of colli*
fion. Many in this age, who write and Spe¬
culate on phyfical fubjedfs, feem to fall into
a like error; while they employ their whole
fludy in endeavouring to reconcile all phce-
mmena with the new principles difcovered by
Sir Ifaac Newton : and, when they find, to
their mortification, that this will not always
fucceed ; phenomena muft be difguifed, and
Nature tortured, to hide their ignorance.
From the lazy method of philofophizing in
the clofet, among books and diagrams, there
never arofe, there never will arife, any difi*
Covery of confequence : Great inventors u*
fually under ftand the extent of their own
principles too well, to leave much of the ap*
plication of them to others.
The difcovery of the different refrangibi*
lity of the rays, was an ineftimable addition
to natural knowledge ; as it ferves, at once,
for explaining innumerable phenomena in Na¬
ture which flow from it as immediate and
neceffary confequences : and, if it fliall be
demonftrated by the obfervation propofed in
N° 49. that the differently-coloured rays
really ,
PHYSICAL and LITERARY. %
y 4 9 • ».
really move with different velocities, our
theory of light will be ftill farther improved ;
as the different refrangibility can be thence
mechanically explained.
The whole fyftem of Nature is one i ru¬
men fe feries of caufes and effeds, whofe be¬
ginning and end are equally hid in the
depths of infinity. Only a fmail, a very
fmall portion of it, comes under our imme¬
diate obfervation ; being expofed alike to
the fight and other fenfes of all mankind.
Almoft every ph<znome?vm is, at once, the
caufe of manifold eflfeds 5 and one effed,
among many, of a fuperior caufe. The bu-
finefs of Science is to extend our views, by
unfolding the latent caufes which exift in
Nature ; and thence explaining their mani-
feft effeds. The difcovery of one fuch
real caufe, unknown before, if it be of ge¬
neral or very extenfive influence, as that of
univerfal gravity, is to be efteemed a great
advancement of natural philofophy. To
undervalue fuch a difcovery, as fome have
done, becaufe the caufe of that caufe can¬
not yet be afligned, is highly abfurd : fince
the fame objection muft for ever ly againft
Vol. II. M all
go ESSAYS anet OBSERVATIONS
all caufes, except primary ones ; which are
certainly removed far beyond the reach of
human inquiry. The proper office, and
higheft boaft of true philofophy, is, to
bring us ftill nearer to the Deity, by lead¬
ing us upwards, ftep by flep^ in the migh¬
ty fcale. of Nature* s . :
i ” ,
r> - . * - . ■ , . .
V ' 1 - * - • • • t . * ' 1 '• * • '
'* '* ; ■ r. ? f>r\ ■ r •
• ' - - * *-* - • ^ -• A-*- ~ i ■ .
*
' s
/
' V
\
J
I
t
/
\
I
\
• I
v >
I
PHYSICAL and LITERARY, fi
Art. V.
•' ■**
An eajy Method of computing the Parallaxes
of the Moon ^ , by - **—
t* ♦ r *
•••. ' , c. : , : ■ "i, ; • ;; r. ;
\-> *
TA B. IV. fig, i. i. If from ©, the
center of the fun, a right line ©W be
carried round, always touching the earth's fur-
face, this line will form a conical furface;
which, being cut, by a plane palling through
the center of the earth, at right angles to the
i • * »
line joining the centers of the fun and earth,
the fedlion, fo made, is the difk of the earth.
/•'' • rf * % . Y f A *
2. The fame conical furface will cut off a
circular portion of the moon's fphere, wn e S}
within which, any arches, intercepted by
lines drawn from the center of the fun and ex¬
tended to the difk of the earth, will be nearly
in the fame proportion to one another, as the
refpeftive diflances intercepted on the difk.
3. Hence, c being the center of the circular
portion, fyce the ecliptic ; if the femidiameter
of the difk be expreffed by the number of fe-
conds in the arch cw or c e~ horizontal pa¬
rallax
* November 6th, 1755.
m ESSAYS and OBSERVATIONS
>
railax of the moon from the fun, every line
drawn on the difk will be expreffed by the fe-
conds of its correfpondent arch of the moon’s
fphere.
4. Let C be the center of the difk, W E,
N S, the projections of we the ecliptic, and
ns a circle of latitude j WNE being the up¬
per or northern femicircle, and WSB the
lower or fouthern. Let V be the place of a-
ny given vertex on the difk, and v the cor¬
refpondent point in the moon's fphere 3 VA,
V B, perpendiculars to N S, W E, and v a ,
v b their correlatives. If the point v be the
true place of the moon,, u e. if the vifible pla¬
ces of the fun and moon be the fame, then
will VA be the par. Ion. 3) a ®, and VB
the par. lat. to a fpeCtator at the point V on
the difk, or at the given vertex on the furface
of the earth. For the par. Ion. D a © is the
difference of the vif. ion. 2 a © obferved at
V and C : but the vif. long. D a © obferved at
C, is the fame as if feen from A ; therefore
I the par. Ion. 5> a © is equal to the difference
of the vif. Ion. , a © obferved at V and A,
which is equal to the arch va the meafure
of V A. In like manner, V B may be proved
• to
PHYSICAL and LITERARY.
93
to be the par. lat. D a @ ; the vif. lat. being
the fame when obferved at B or C.
5. In any* other pofition of the moon, if its
diftance from the point v exceeds not one de¬
gree, which it can never do in the time of an
eclipfe ; the parallaxes, to a fpeftator at the
point V of the difk, wdll continue nearly the
fame as before, without any fenfible alteration.
Let / be the place of the moon, l d, lf> perpen¬
diculars to c n, ce j and let//, v a, be pro¬
duced till they meet in the pointy, and let Id
meet with vb in the point t ; the vif. Ion. 2>
d ©, will be nearly the fame at the points
g and /. Therefore the vif. long d ©, ob¬
ferved at V, is the angle under which the
arch vg is feen from that point. But the arch
vg will be feen nearly under the fame angle
from the points V and C ; and confequently it
is the meafure of the vif. Ion. D d ©. But the
true Ion. is dl—ag : therefore vg — ag zz va
is the par. Ion. Da®. Again, a d zz / g zr. vif.
lat. ]) aq; and cdzzfl— tr. lat. : therefore
v b — a c — a d 4- d c — par .lat. D a ©.
6. But thefe parallaxes va, vb, and the
vif. Ion. and lat. vg, vt, fuppofe the fpedtator
at the point V on the difk ; whereas his
true
54 ESSAYS and OBSERVATIONS
true place is at the correfpondent point of
the furface of the earth ; confiequently,
the vif. Ion. and lat. a ©, vg , vt,
muft be increafed in the ratio of the di-
fiance of the point ro from the fpettator’s place
,on the furface, to its diftance from the point V
on the difk. But, as the horizontal femidiame-
ter of the moon fhould likewrfe be increafed
in the fame ration it will equally anfwer the
purpofe of finding the times and phafis of an
eclipfe, to let thefe continue unaltered, and to
diminifh the fun’s apparent femidiameter in
the fame ratio.
7. Let C P be the axis of the earth pro-
jetted on the difk, F M D the ellipfe into
which the parallel of the given place is pro-
jetted, D F its greater axis, O M its lefier fe-
miaxis, V G perpendicular to C O j M H,
G K, perpendiculars to CW, and M I, G L,
at right angles to C N and, for fhortening
the rules, put C W, the femidiameter of the
difk, or the horizontal parallel D a ©3 equal
to the radius of the tables of fines and tan¬
gents.
8. For computing the parallaxes V As
V B, it will be convenient firft to fuppofe the
fun 111 the meridian, and the place of the vei-
PHYSICAL and LITERARY. 9S
tcx at M ; then to compute the variation of pa¬
rallaxes, for the given time, from noon.
9. The meridian par. Ion. 3) a © is MI or CH ;
and the meridian par. lat. D a © is M H or
Cl : for finding which the requifites are.
Cof ^ ^at* ^ie P^ace>
j To be found
Sine ? ’
£o(- > of the declination of the fun, ^ from the
Sine? rT^XT , f . 'l Tables.
q0£ r of PCN ~ complement of the meriaian angle, J
^ W* IL ■ * * -«► V v . ;
n r _ S, lat. pi. X cof. decl. O J North \ if the lat. f North.
“ J[ \ South. f pi. be South.
‘ ’ •' - ' <8
Cof. lat. pi. X S, decl. O of a contr. fpec. to the decl. q.
R v ,
► * f A
r A/r_ C Biff. ? C C and O M, if they C the fame 7 1 c *
C M- 1 Sum 5 are of ' { different $ SPecles'
Merid.par
. par. Ion. » 2 G=MI=HC~ p^erid.ang.
Eaft
Weft
7 f i C Summer 7.^., C Winter 7 folftice C North.
^fromthe|Wjn£er jtothej 5^ South.
. n/rTT _ . — . CMX S, merid. ang. C of £
Merid. par. lat. D a O = MH=IC = - - R- - & | fpec_
a contr.
to CM.
10. The variations from the merid. parallaxes
for the given hour from noon, may be conceived
to be made up, each of two parts ; which are the
projections of MG and GV upon CW for the Ion.
and upon CN for the lat. : the former being HK,
' KBs
s6 ESSAYS and OBSERVATIONS
KB; and the latter I L, LA. For finding which,
befides the foregoing requifites, there is required
" _ 1 • f ' . -\
VeH" Sine \ — ^^Srees ^rom R00n»
_ , ~ OM X verf. S, deg. a noon
MG= - - - ^ -
GV
V
Cof. lat. pi. X S, deg. a noon
' — £ -
Variation of the Par* Lon. d a O.
4 « '■ - i li i >’ • ••
<
MG X cof. merid. ang.
ift Part —
Weft?
R
Eaft 5
when the fun is in
■w «w x r « n.
S SI IK a ni ^ ,
, _ GV X S, merid. ang. C Eaft AM.
jd Part = - - - s | Weft PM.
o
Variation of the Par. Lat. 5 a ©.
■ * > < *\ i . .. *
„ r, MG XSt mend. ang. C South ? . t
[ft P art — - - - - < North ^contrary to the decl.0,
sd Part
£ North ^
GV X cof. merid. ang.
R
^ <; South ?, . . . (yprXVy I,
forenoon | North | when tne lun ls m | s ^ Ift * 1ft. f .
,r C North ? , , , . . C HP K T B. Hr
Afternoon £ South £ when the fun is in ^ $ ft ift - Ift f .
ii. Bv
PHYSICAL and LITERARY, 9?
1 1. By art. 6. the part to be fubtrafted
from the apparent femid. © mud bear the
fame proportion to the whole, as the di¬
ftance of the vertex on the furface of the
earth from its point on the difk, to the di~
ftance of the points V, v ; which is nearly
the fame with the femidiameter of the
moon’s orbit, and may always be expreffed
by a conftant number, viz. that of the 2ds
of a degree equal to the radius of a circle.
The diftance of the vertex from its point on
the difk may be conceived to be made up of
two parts, poftive , or negative : the firft of
which is the perpendicular diftance of the
centre of the given parallel circle from the
plane of the difk; the fecond part is the per¬
pendicular diftance of the given vertex from
a plane palling thro’ the forefaid centre, and
parallel to the difk.
4 p , ?.T _ S, lat. pi X S, decl. Q Pof. 1 when the 1st. pi
R cNeg. 5 and decl. Q are
of
the fame
\ Species.
^ different 5
, „ Cof. lat. pi X cof. decl. O X co^ « 110011
xd Part = r - — - - - -
RR
Pofitive ? th jyen hour from noon be j J; ‘5 \ than 6°
Negative 5 6 C more J
VOL. II.
N
12. It
9S ESSAYS AND OBSERVATIONS
12. It would be eafy, from the foregoing
rules, to conftrud tables of the parallaxes for
any given latitude. Such tables would be
fufficiently exadt, if calculated for every
third degree of the fun’s longitude, and e-
very quarter of an hour from noon to 6
hours, affirming ioooo for radius, or the ho-
riz. par. ^ a 0. The equation to be fubtra-
dfed from the apparent femid. 0 needs only
be calculated for every ioth degree of longi¬
tude, and every half hour from noon to 6
hours, taking the mean femid. ©.
13. If the given time from noon be more
than 6 hours, fuhtraft it from 12 hours, and
the Ion. © from 12 figns ; and, for the re¬
maining time and longitude, feek the intire
parallax, and the equation for the femid. ©3
changing its fign.
14. Such tables* tho’ conftrudted for a
particular latitude, may eafily be made to
ferve for any other latitude. For the varia-
tions from the meridian parallaxes are always
proportional to the cofine of latitude. And
the meridian parallax, whether of Ion: or
lat. is made up of the fum or difference of
two parts 3 the firft of which is proportional
to the fine, the iecond to the cofine of lat.
Thefe
PHYSICAL and LITERARY. 99
Thefe two parts for the tabular latitude are
found thus. To the given Ion. 0 add 6 fig ns 5
and take out the merid. parallax anfwering
to each longitude. Half the fum of thefe
gives the ift part, and half their difference
the 2d part, to be added to the firft when the
merid. par. for the given Ion. © is greater than
the other, and to be fubt rafted when lefs. In
like manner, the equation for the femid. ®
confifis of two parts; the ift of which is pro¬
portional to the fine, the 2d to the cofine of
lat. The ift part is the equation for the given
Ion. ©, and 6 hours from noon ; and this
fubtrafted from the equation for the given
Ion. © and hour from noon, gives the
2d part.
15. The fame rules will ferve for finding
the moon’s parallaxes from a fixt fiar or p a-
net. If the femid. of the p’anet have no
fenfible magnitude, there will be no place
for the correction mentioned in art. 6. But,
as the requifites could not be found from the
common tables, if the fiar has latitude, it
will be convenient, fir ft, to Juppofe it lias
none, and afterwards to apply a proper cor¬
rection. Befides, the proceeding in this way
will make the tables already defcnbed to be
c
or
100 ESSAYS AND OBSERVATIONS
of the fame ufe as in folar eclipfes, fubftitu-
ting the Ion. # for the Ion. ©, and, for the
hour from noon, the equatorial diftance of
the ftar’s ecliptic place from the meridian,
converted into time at the common rate of
1 5 degrees to an hour.
1 6. Jf the ftar have latitude, then the
true Ion. and lat. ^ a * are meafured by ar¬
ches, from the center of the moon, perpen¬
dicular to a circle of latitude, and to a great
circle at right angles to it, both paffing thro'
the ftar. Hence,
As radius to cof. true lat. fG tr. Ion. >
a ^ to the fame projected. And,
As cof. tr. Ion. p a * to radius, fo tan.
tr. lat. P to the fame projected : or,
without any fenfible error, fo tr. lat. $
to the fame projedled,
17. To find the correflion of the paral¬
laxes for the latitude of a ftar : let C W
(fig. 2,) be the ecliptic on the earth’s fur-
face, N its pole ; CN a circle of latitude
thro’ the ftar ; W its pole 5 V the given ver¬
tex, CD, the lat. « ; WVA a great circle
thro’ the vertex V, meeting with the circle
gf
PHYSICAL and LITERARY, ioe
of latitude in A, WD another great circle ;
VB, W, arches perpendicular to WC, WD.
Then WA is a quadrant, and the fine of V A
is the par. Ion. D a * , whether the far has
latitude, or not : the fine of VB is the par.
]at. if the flar be in the ecliptic ; but, if it is
in the circle WD, the par. lat. will be the
fine of Yb 5 which may be found from the
parallaxes of Ion. and lat. given for the ecli¬
ptic place of the ftar : thus,
S, WVzz Cof. VA ~ v/R •+■ par. Ion. X R— par. ion.
c VWn __ R X S, VB (par, lat)
^ X W ~ S, WV
VW£ = VWB £ + | CWD, if the lat * be £
S, WV X s, vw£
S, Vb — par. lat. D =
R
18. Since the radius of the tables of fines
and tangents was all along taken for the ho-
riz. par. I a © or * ; the parallaxes and
equation found muft be altered propor¬
tionally.
E X A M-
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Physical and literary. 105
Art. VI.
A Solution of Kepler’ s Problem ; by Matthew
Stewart, Profeffor of Mathematics in the
Univerfty s/* Edinburgh •*.
THO’ the problem propofed by the cele-
brated Kepler has been Solved by Seve¬
ral Mathematicians of great note : yet, as
this is of considerable ufe in aftronomy, it is
hoped the following Solution may be agree¬
able to fome ; as it requires a lefs degree of
knowledge in the more difficult parts of Ma-\
thematicSj than the other methods do.
PROP. 1. Tab. V. Fig. i.
Let there be a {freight line AB, and
CD a portion of a curve wholly
concave towards AB, and draw AC,
%
BD parallel to each other, meeting
the curve in C, D ; let C E, a tan-
Vol. II. O
* December 4, 1 7 5 5^
gent
xo6 ESSAYS and OBSERVATIONS
gent to the curve at C, meet BD
in E; join AD, AE, BC, and let
AE meet the curve in F : the tri¬
angle ABC will be greater than the
fector ACF, but lefs than the fe-
6tor ACD.
\
Join CD. Becaufe AC, BE, are parallel,
the triangles, ABC, AEC, wilt be equal:
but the triangle AEC is greater than the
fedor ACF ; therefore the triangle ABC
is greater than the fedor ACF. Again, be-
caufe AC, BD, are parallel, the triangles,
ABC, ADC, are equal : but the triangle
ADC is lefs than the fedor ACD ; therefore
the triangle ABC is lefs than the fedor ACD„
: PRO P. ' II. Fig. 2.
Let there be a curve AEB, wholly
concave towards the ftreight line
AB, and let C, D, be two points in
the line AB ; draw DE to any point
E
\
PHYSICAL and LITERARY. 107
E in the curve, and drawCF paral¬
lel to DE, meeting the curve in F ;
let EG, a tangent to the curve at E,
meet CF in G, and join DF, DG,
and let DG meet the curve in H ;
let the point D be between the
points, A, G : the feet or ACE will
be greater than the lector ADH,
but lefs than the lector ADF ; and
the fedtor BCE will be greater than
the fe&or BDF, but lefs than the
lector BDH.
Because the triangle DEC is greater than
the fedor EDH, let the fedor ADE be added
to both ; and the (pace ACE will be greater
than the fedor ADH : and, becanfe the tri¬
angle DEC is lefs than the fedor EDF, let
the fedor ADE be added to both ; and the fe-
dor ACE will be lefs than the fedor ADF.
Again, becaufe the fedor ACE together
with the fedor BCE, is equal to the fedor
ADF together with the fedor BDF, and the
fedor
io8 ESSAYS and OBSERVATIONS
fedor ACE is lefs than the fedor ADF ;
therefore the fedor BCE is greater than the
fedor BDP : and, becaufe the fedor ACE to¬
gether with the fedor BCE, is equal to the
fedor ADH together with the fedor BDH,
and the fedor ACE is greater than the fedor
ADH ; therefore the fedor BCE will be lefs
than the fedor BDH.
PROP. III. Probl. i. Fig. 3.
Let there be a given circle AEB, and
let D be a given point within the
circle; and from D let there be
drawn DE, DF, to two given
points, E, F, in the circle : granting
the quadrature of the circle, it is
required to draw a line DG meeting
the arc FE in G ; fo that the fector
EDG may be to the fector GDF in
a given ratio, fuppofe that of m to n.
Let C be the center of the circle, and join
€E, CF \ draw DH, DK5 perpendicular to
CES
PHYSICAL and LITERARY. 109
CE, CF, meeting CE, CF in FI, K ; and let
EL, FM, be tangents to the circle at the
points, E, F.
Because the points, D, E, F, are given,
and the circle is given, the fe&or DEF will
be given ; and, becaufe the fe&or EDG is to
the fe&or GDF in the given ratio of m to ny
the fe&ors, EDG, GDF, will, each of them,
be given in magnitude. In the tangent EL
take the point L towards F ; fo that, joining
HL, the triangle HEL may be equal to the
fe&or EDG : again, in the tangent FM take
the point M towards E 5 fo that, joining KM,
the triangle KFM will be equal to the fe&or
FDG : it is evident, the points, L, M, will be
given. Join DL, DM, meeting the circle in
N, O ; the point G will fall between the
points, N, O. For, becaufe EL, FM, are
tangents to the circle at E, F, the angles
HEL, KFM, will be right ; and therefore
DH, EL, will be parallel : likeways DK, FM,
will be parallel ; therefore the triangles,
DEL, HEL, will be equal, and likeways the
triangles, DFM, KFM, will be equal : and
therefore the triangle DEL will be equal to
the fe&or DEG, and the triangle DFM equal
n® ESSAYS and OBSERVATIONS
to the fedor DFG; therefore the fedor DEG
will be greater than the fedor DEN, and the
fedor DFG greater than the fedor DFO;
therefore the line DG will fall between the
lines, DN, DO ; therefore the point G will
fall between the points, N, O.
Again, Becaufe the points, L, M are
given, and the point D like ways given, the
fedors, DEN, DFO, will be given 5 and, be¬
caufe the fedors, DEG, DFG, are given,
the fedors, DNG, DOG, will be given ; and
therefore the fedor NDG will be to the fe¬
dor GDO in a given ratio, fuppofe that of
p to q. The problem, therefore, will be re¬
duced to this again, To divide the fedor
NDO by the line DG, fo that the fedor
NDG may be to the fedor GDO in the gi¬
ven ratio of p to q. And thus, repeating the
operation, the point G will be found within
a very narrow limit.
N. j B. The limit ON might have been
found by taking in the tangents, EL, FM,
the point L towards F, and the point M to¬
wards E ; fo that, joining DL, DM, meeting
the circle in N, O, the triangle DEL would
be equal to the fedor EDG, and the triangle
PFM -
PHYSICAL and LITERARY in
DFM equal to the fedtor DFG: but the
other way points out the method of cal¬
culation.
PROP. IV. Probl. 2. Fig. 4>'
Let there be a femicircle whofe dia¬
meter is AB and center C, and let
D be a point in the diameter:
granting the quadrature of the cir¬
cle, it is required to draw a line DE
meeting the circle in E, fo that the
femicircle may be to the fedlor
BDE in a given ratio, luppofe that
of> to q.
Suppose the problem folved. Let the fe¬
micircle be to the fedtor BCF as p is to q $
join DF ; draw CG parallel to DF, meeting
I G, a tangent to the circle at F, in G, and
join DG meeting the circle in H ; let CG
meet the circle in K, and join DK, FK, CFL
Because the femicircle is to the fedtor
BDE asp toy, that is, as the femicircle to the
fector
i 12 ESSAYS and OBSERVATIONS
fedor BCF, the fedor BDE will be equal to
the fedor BCF : but the fedlor BCF is
[Prop, 2. ] greater than the fedor BDK, but
lefs than the fedor BDH ; therefore the fedor
BDE is greater than the fedor BDK, and lefs
than the fedor BDH ; therefore the line DE
falls between the lines, DH, DK 5 and there¬
fore the point E falls between the points, H,
K. Again, becaufe the fedor BDE is equal
to the fedor BCF, and the fedor BCIv is
common to both, the fpace KCDEK will be
equal to the fedor KCF ; and, becaufe the
triangles, KCD, KCF, are equal, (becaufe
KC, DF, are parallel), therefore the fedor
KDE is equal to the fpace KEFK ; and, be¬
caufe the triangles, GDK, GFK, are equal,
taking the common fpace GHK from both*
the fedor KDIT will be equal to the fpace
KEFK together with the fpace GFHG; but
the fedor KDE is equal to the fpace KEFK,
therefore the fedor EDH is equal to the
fpace GFHG.
Because the femicircle is to the fedor
BCF as p to q, therefore the angle BCF is
given, and therefore the angle FCD is like-
ways given : and, in the triangle FCD, be¬
caufe the fides, CF, CD, are given, and like-
ways
PHYSICAL and LITERARY, r 1.3
ways the angle FCD, the angles CDF,
CFD will be given; and therefore the
angles BCK, KCF will be given ; therefore
the arcs BK, KF are given: hecaufe FG is
a tangent to the circle at the point F, the
angle CFG will be a right angle: and be-
caufe the angle FCG is given, and likeways
the fide CF given, the fides CG, CF will
be given : in the triangle GCD, becaufe the
fides GC, CD are given, and the angle GCD
given, the angles CGD, CDG will be given:
and in the triangle GCH, becaufe the fides
GC, CFI and the angle CGH is given, the
angle GCH will be given ; and therefore the
arc HK will be given : and becaufe the arc
FK is given, therefore the arc FH is given.
Again, becaufe the arc FK is given, the fedtor
FCK will be given, and likeways the tri¬
angle FCK given, therefore the fpace
KEFK will be given ; and becaufe the
triangles, GFC, GHC, are given, the fpace
GFCHG will be given ; and becaufe the arc
FH is given, the fedtor FCH will be given 3
therefore the fpace GFHG will be given,
V 0L1 IL P Profit
1 14 ESSAYS and OBSERVATIONS
From this , the following conjlrnBion may be
deduced .
't ■ -- *
CONSTRUCTION.
In the femicircle take the point F, and
let the arc AFB be to the arc BF
as p is to q) join CF, DF, and draw
CG parallel to DF, meeting FG, a
tangent to the circle, at F in G; and
the circle in K; join DG meeting the
circle in H, and join FK, DK ; draw
the line DE \Trop. :>.] meeting the
circle in E, fo that the fe£lor KDE
may be to the feftor EDH as the
fpace KEFK to the fpace GFHG:
the i'emicircle will be to the fe£tor
BDE as f is to q.
Because the fe&or KDE is to' the feftor
EDH, as the fpace KEFK to the fpace
GFHG 5 the fedor EDH will be to the
fedtor KDH, as the fpace KEFK to the fum
of the fpaces KEFK, GFHG : but, becaufe
the
PHYSICAL andLITERARY. ii*
the triangles, GDK, GFK are equal, and the
fpace GHK common to both, the fedtor KDH
will be equal to the fum of the fpaces KEFK,
GFHG ; therefore the fedtor KDE is equal
to the fpace KEFK. And, becaufe the tri¬
angle KDC is equal to the triangle KFC, the
fpace KCDE will be equal to the fedtor KCF;
therefore (adding the fedtor BCK to both)
the fedtor BDE will be equal to the fedtor
BCF. A^ain, becaufe the arc AFB is to the
arc BF as p is to y, the femicircle will be to
the fedtor BCF as p is to q ; therefore the
femicircle will be to the fedtor BDE as p is
to q. Ch E. D,
But, as this would require a good deal of
trigonometrical calculation, the following
method may be ufed ; which will give the
point fought very nearly, when this problem
is of ufe in the planetary fyftem*
PROP. V. Probl. 3, Fig. 5.
Let there be a femicircle ‘whofe dia¬
meter is AB and centre C, and let
D be a point in the diameter not
very
'll 8 ESSAYS and OBSERVATIONS
very excentric ; granting the qua¬
drature of the circle, it is required
to draw a line, DE, meeting the
circle in E, fo that the femicircle
may be to the feftor BDE in a
given ratio, fuppofe that of^> to q.
Suppose the problem folved ; and let the
femicircle be to the fedor ECF as p is to q ;
join DF, and draw CG parallel to DF meet¬
ing FG a tangent to the circle at F in G 5
join DG, and let CG, DG meet the circle
in H, K : joih DH, FH ; draw CM parallel
to DH meeting HM a tangent to the circle
at H in M ; draw DL perpendicular to CH
meeting CH in L ; join LE, and let FN
perpendicular to CH meet CFI in N.
Because the femicircle is to the fedor
BDE as p is to q , that is, as the femicircle to
the fedtor BCF, the fedor BDE will be equal
to the fedor BCF : and becaufe the fedor
BCH is common to both, the fpace HCDE
will be equal to the fedor HCF ; but be¬
caufe CH, DF are parallel, the triangle
DCH is equal to the triangle FCH 5 there-
fore
PHYSICAL and LITERARY. 1x7
fore the fedor EDH will be equal to the
{pace contained by the arc HF and the chord
FH. Again, becaufe the fedor BDE is
equal to the fedor BCF, and the fedor BCF
is [Prop. 2.] greater than the fedor BDH,
and lefs than the fedor BDK, the fedor
BDE will be greater than the fedor BDH,
and lefs than the fedor BDK: therefore the
point E is in the arc HK between the points
H, K. [Let the arc HK be called the limi¬
ting arc]. Becaufe the point D is not very
excentric, the limiting arc will be little. In
the orbit of Mercury , the mod excentric of
all the planets, the limiting arc will be lefs
than fixteen minutes in that part of the orbit
where it is greateft ; therefore EH may be
coniidered as coinciding with the tangent to
the circle at the point H 5 and therefore the
triangle ELH will be equal to the fedor
EDH, that is, equal to the fpace contained
by the arc FH and the chord FH; therefore
the redangle LHE will be double of the
fpace contained by the arc FI I and the chord
FH. Becaufe the redangle contained by
CH and the arc FH is double of the fedor
CFH, and the redangle contained by CH,
L.N is double of the triangle CFH; the
redangle
ii3 ESSAYS AND OBSERVATIONS
redangle contained by CH and the excefs of
the arc FH above FN will be double of the
fpace contained by the arc FH and the
chord FH ; therefore the redangle LHE
will be equal to the rectangle contained by
CH and the excefs of the arc FH above
FN ; therefore LH will be to HC as the
excefs of the arc FFI above FN to FIE ;
but becaufe the triangles DLIL CHM are
fimilar, LH will be to HC as DL or FN
to HM ; therefore FN will be to HM as
the excefs of the arc FH above FN to HE,
From this, the following confruction may he
deduced .
CONSTRUCTION.
Let the femicircle be to the fecior
BCF as p is to q\ join DF, draw
CH parallel to DF meeting the
circle in H ; join DH, draw CM
parallel to DH meeting HM a
tangent to the circle at H in M;
and let FN perpendicular to CH
meet CH in N 5 in the tangent,
HM
PHYSICAL and LITERARY, i iq
HM take HE towards F, (o that
FN may be to HM as the excels
of the arc FH above FN to HE;
join DE: the femicircle will be
to the feftor BDE as p is to q.
Let DL, perpendicular to CH, meet CH
in L y join FH, LE. Let CH meet FG, a
tangent to the circle at F, nn G 3 join DG
meeting the circle in K.
Because the triangles DLH, CHM are
limilar, LH will be to HC as DL or FN to
HM 5 that is, as the excels of the arc FH
above FN to HE : therefore the rectangle
LHE will be equal to the re&angle con¬
tained by HC and the excefs of the arc HF
above FN ; but, becaufe the reftangie con¬
tained by CH and the arc HF is double of
the fedlor HCF, and the redtangle contained
by CH, FN is double of the triangle CFH ;
therefore the redtangle contained by CH and
the excefs of the arc FH above FN will be
double of the fpace contained by the arc
1 H and the chord FH ; therefore the rect¬
angle LHE will be double of the fpace
contained by the arc FH and the chord FI I;
and
1 20 ESSAYS AND OBSERVATIONS
a
and therefore the triangle LHE will be equal
to the fpace contained by the arc FH and
the chord FH : but, becaufe DL, FIE
are parallel, the triangles DHE, LHE are
equal $ therefore the triangle DHE is equal
to the fpace contained by the arc FFI and
the chord FH: and, becaufe DF, CH arc
parallel, the triangles CDH, CFH are equal;
therefore the fpace HCDE will be equal to'
the fedor CFH* Let the fedor BCH be
added to both, and the fedor BDE will be
equal to the fedor BCF 2 but, becaufe the
fedor BCF is greater than the fedor BDH
and lefs than the fedor BDK, therefore the
fedor BDE is greater than the fedor BDH
and lefs than the fedor BDK, and therefore
DE falls between DFJ, DK : and, becaufe
the point D is not very excentric, the limi¬
ting arc HK will be little ; therefore the1
tangent HE may be confidered as coinciding
with the arc HK : becaufe the fedor BDE
is equal to the fedor BCF, the femicircle
will be to the fedor BDE as the femicircle
to the fedor BCF : but the femicircle is to
the fedor BCF as p is to q ; therefore the
femicircle is to the fedor BDE as p is to q .
Q^E. D.
Kepler .
PHYSICAL and LITERARY, tit
Kepler fir ft of all difeovered that the pla¬
nets revolved in ellipfes round the fun placed
♦ »
in one of the foci , and that they de (bribed
equal areas in equal times round the fun. Let
the femi-ellipfe, [Fig. 6.] whofe greatef axis
is AP, focus S, and centre C, reprefent half
the orbit of a planet round the fun in S; and
fuppofe the planet at the point K in its orbit j
join SK : half the periodic time of the planet
round the fun, is to the time the planet movei
from A to F, as the area of the femi-ellipfe
to the area ASK 3 and therefore to find the
place of the planet at any given time, it is
neceffary to find the pofition of the right
line SK, which fhall cut off the area ASK
proportional to the time, that is, To draw thd
line SK fo that the area of the femi-ellipfe
may be to the area ASK, as half the periodic
time of the planet round the fun to the
given time.
From K let fall KH perpendicular to AP*
meeting the femicircle deferibed upon AP in
G, and join SG : it is evident, from the na¬
ture of the ellipfe and circle, that the femi¬
circle is to the fedtor ASG as the femi-ellipfe
to the fedtor ASK 3 therefore the femicircle is
to the fedtor ASG as half the periodic time of
V oh i IL Q thd
1
/
•122 ESSAYS AND OBSERVATIONS
the planet round the fun to the time the
planet moves from A to K : the problem
therefore is reduced to this, To draw the
line SG meeting the femicircle in G, fo that
the femicircle may be to the febtor ASG as
half the periodic time of the planet round
the fun to the given time. In the femicircle,
take the arc AB, fo that the arc ABP may be
to the arc AB as half the periodic time of the
planet round the fun to the given time, join
CB 5 the femicircle therefore will be to the
febtor ACB as half the periodic time of the
planet round the fun to the given time, that
is, as the femicircle to the febtor ASG ; there¬
fore the febtors ACB, ASG, are equal ; join
CG.
The angle ACB is called by Kepler the
mean anomaly, the angle ACG the anomaly
of the excentric, and the angle ASK the co~
equate or true anomaly. The problem there¬
fore is reduced to this : The mean anomaly
of a planet being given, to find the anomaly
of the excentric and the coequate anomaly.
*
PRO P,
PHYSICAL and LITERARY. 123
PROP. VI. Probl. IV. Fig. 6.
Let AP be the greater axis of a pla¬
net’s orbit, S the focus the place
of the iun, A the aphelion, P the
perihelion ; upon AP let the fe mi-
circle ABP be defcribed ; let C be
the center, and let the angle ACR
be the mean anomaly of the planet
at any given time : it is required
to find the anomaly .of the excen-
tric.
Join SB, and draw CD parallel to SB
meeting the circle in D : join SD in BD :
take the arc DG, fo that the fine of the angle
BCD may be to the tangent of the angle
CDS, as the excefs of the arc BD above its
fine to the arc DG ; and join CG : the
angle ACG will be nearly the anomaly of the
excentric.
Join SG 5 draw BE perpendicular to CD
meeting CD in E, and draw CP parallel to
SD meeting DF a tangent to the circle at D
in F.
Because
124 ESSAYS AND OBSERVATIONS
Because BE is the line of the angle
BCD, and DF the tangent of the angle
DCF, that is, of the angle SDC ; BE will
be to DF as the excefs of the arc BD above
BE to the arc DG ; therefore [Prop. 5.] the
fedtor ASG is equal to the fedlor ACB 5
therefore the angle ACG is the anomaly of
the excentric*
The computation is as follows : In the
triangle BCS, as the fum of the lides BC, CS,
is to the difference of the lides BC, CS, fo is
the tangent of half the angle ACB to the
tangent of half the difference of the angles,
CSB, CBS ; therefore the angles, CSB, CBS
will be given, that is, the angles, ACD,
DCB, will be given. Again, in the triangle
CSD, the fum of the fides, CD, CS, is to
the difference of the lides CD, CS, as the
tangent of half the angle ACD to the tangent
of half the difference of the angles, CSD,
CDS 5 therefore the angle CDS will be
giyen. Again, becaufe as the line of the angle
BCD is to the tangent pf the angle CDS, fo
is the excefs of the arc BD above its line to
the arc GD ; fay as the radius is to the fine
pf the angle BCD, fo is 570. 2957795 &c-
fhe number of degrees in an angle fubtended
PHYSICAL and LITERARY, xsf
by an arc equal to the radius, to the number
of degrees in an angle fubtended by an arc
equal to the fine of the angle BCD ; [let
this angle be called A]. Again, as the fine
of the angle BCD to the tangent of the angle
CDS, fo is the excefs of the angle BCD
above the angle A, to the angle GCD.
Therefore the angle ACG, the anomaly of
the excentric, will be given.
EXAMPLE I.
In the orbit of Mercury , the mean diffance
is to the excentricity as iooooo to 20589,
Suppofe the mean anomaly from the apheli¬
on to be 6o°, it is required to find the ano¬
maly of the excentric. In the triangle BCS,
as 120589, the furn of BC, CS, is to 7941 1
the difference of the fides BC, CS, fo is the
tangent of 30°, half the fum of the angles,
CSB, CBS, to the tangent of half the differ¬
ence of the angles CSB, CBS.
The log. tang, of 30° is 9.7 614394
The log. of 7941 1 is 4.8998807
The fum is 14.66 13 201
The log. of 1 20589 is 5.0813077
The difference
"3 i \ 1 • L' i \ . L
9.5800124 is the
jpg.
*26 ESSAYS AND OBSERVATIONS
log. tang, of 20° 49'. 00894 half the difference
of the angles CSB, CBS 5 therefore the an¬
gle CSB or ACD is 50° 49'.oo894, and the
angle CBS or BCD is 90 io'.99io6. Again,
in the triangle DCS, as 120589 the fum of
DC, CS, is 1079411 the difference of DC,
CS, fo is the tangent of 250 24". 50447 half
the fum of the angles CSD, CDS, to the tan-
i
gent of half the difference of the angles
CSD, CDS.
The log. tang. of 250 24'. 504 47 is 9.6767070
The log. of 794.1 1 is 4.8998807
The fum is 14.5765877
The log. of 120589 is 5.0813077
The difference 9.4952800
is the log. tang, of 17?- 22821093 half the dif¬
ference of the angles CSD, CDS ; therefore
the angle-CDS is 8° 2829354. Again, as the
radius is to the fine of 90 10899106, fo is
570 .2957795 t^le number of degrees
in an angle fubtended by an arc equal
to the radius, to the number of degrees and
minutes in an angle fubtended by an arc equal
to the fine of 90 10899106.
• * The
I
PHYSICAL and LITERARY. 127
The log. of 57.2957795 is j. 7581226
The log. fine of 90 10'. 99106 is 9.2030097
The fum is 10.961 1323
The log. of rad. is 10.0000000
The difference v 0.9611323
is the log, of 90 8'. 6349999, the number of
degrees and minutes contained in an angle
fu biended by an arc equal to the fine of
90 10.99 1 06. The angle A therefore is
90 8 .6349999 ; the excels therefore of the
angle BCD above the angle A is 2'. 3 5606.
Again, as the fine of 90 10.99106 is to the
tangent of 8° 2^.293 54, angle
2'. 3 5606 to the angle DCG.
The log. of 2'. 35606 is 0.3721863
The log. tang, of 8° 2'. 29354 is 9.1498998
The fum is 9.5220861
The log. fine of g° 10'. 99106 is 9.2030097
The difference 0.3190964
j
is the log. of 2',o84953 the angle DCG, the
angle ACG the anomaly of the excentric is*
5°° 51'-°93893> tha* « 5°c S1' 5 -6335s-
Let
128 ESSAYS AND OBSERVATIONS
Let SM, perpendicular to CG, meet CG
in M : It is evident, becaufe the fedor ACG
is common to both the fedors ASG, ACB,
that, if the fedor ASG be equal to the fedor
ACB, the triangle SCG will be equal to the
fedor BCG ; and therefore the line SM will
be equal to the arc BG : if the fedor ASG
be greater than the fedor ACB, the triangle
SCG will be greater than the fedor BCG ;
and therefore the line SM will be greater
than the arc BG : and, if the fedor ASG be
lefs than the fedor ACB, the triangle SCG
will be lefs than the fedor BCG ; and there¬
fore the line SM will be lefs than the arc
BG : that is, if the arc AG be greater/
equal, or lefs, than the true anomaly of the
excentric, the line SM will be greater, equal,
or lets, than the arc BG 5 and therefore, the
lefs the difference is between the line SM
and the arc BG, the lefs will the difference
be between the arc AG and the anomaly of
the excentric.
Because the triangles GCH, CSM, are
fimilar, CG is to GO as CS to SM ; that is,
the radius is to the fine of 50° 51 . °93^93
as 20589 to CM.
Th«
PHYSICAL and LITERARY.
129
The log. of 20589 is 4-3 1 3^353
The log. fine of 50° 5B.093797 is 9.8895890
The fum is
The log. of rad. is
The difference
14.2032243
10.0000000
4.2032243
is the log. of SM. Again, as CA to SM, fo is
570. 295779 5>&c. the number of degrees in
an angle fubtended by an arc equal to CA, to
the number of degrees in an angle fubtended
by an arc equal to SM.
\ a
The log. of 570. 2957795, &c. is 1.7581226
The log. of SM is 4.2032243
The fum is 5.9613469
The log. of CA 5.0000000
The difference 0.9613469
is the log. of 90 8/-9o62 5 the number of de¬
grees and minutes in an angle fubtended by an
arc equal to SM : but, becaufe the arc AB is
6o°, and the arc AG is 50° 51'. 093797, the
arc BG will be 90 8'. 906203 ; the difference
therefore between SM and the arc BG
Yol. IL R is
230 ESSAYS AND OBSERVATIONS
is 0^.000047 ; the difference therefore is lefs
than the 354th part of a fecond.
Mr. Machin, in his folution of this pro¬
blem in the Philofophical Tranfadtions,
Number 447. makes the anomaly of the ex-
centric to be 1 290. 14846, when the mean
anomaly reckoned from the perihelion is 120°;
and therefore, if the mean anomaly reckoned
from the aphelion be 6o°, the anomaly of
the excentric will be 50°. 85154, that is
50° 5T.0924,
In order to determine the difference be¬
tween SH and the arc BG according to this
computation.
The log. of 20589 is 4-3r36353
The log. fine of 50° 51'. 0924 is 9.8895888
The fum is 14.2032241
The log. of rad. is 10.0000000
The difference 4.2032241
is the log. of SM. Again, as CA to SM, fo is
570. 2957795, &c. the number of degrees in
an angle fubtended by an arc equal to CA, to
the number of degrees in an angle fubtended
by an arc equal to SM.
The
PHYSICAL and LITERARY. i3i
The log. of 57°. 2957795, &c. is 1.7581226 •
The log. of SM is 4.2032241
The fum is 5.9613467
The log. of CA is 5.0000000
The difference 0.9613467
is the log. of 90 86905998, the number of
degrees and minutes in an angle fubtended by
an arc equal to SM : but, becaufe the arc AB is
6o°, and the arc AG is 50° 5160924, the arc
BG will be 90 869076 ; the difference there¬
fore between SM and the arc BG is 0600 1 602,
very nearly one tenth of a fecond, and is
more than thirty four times greater than the
former difference.
Because AS is equal to the fum of BC,
CS, and PS equal to the difference of BC,
CS ; it is evident, that, if, from the Jog.
tang, of half the angle ACB, the difference
of the logarithms of AS, SP be fubtrafted,
the remainder will be the log. tang, of an
angle, which, if added to half the angle
ACB, will give the angle ASB or ACD;
and, if fubtrafted from half the angle ACB,
will give the angle CBS or BCD.
EX.
132 ESSAYS AND OBSERVATIONS
EXAMPLE II.
In the orbit of Mars} the mean diftance is
to the excentricity as 152369 to 14100..
Suppofing the mean anomaly to be i°, it is
required to find the anomaly of the excentric.
The log. tang, of 30', half the
angle ACB, is 7.9408584
The difference of the logs, of AS,
SP is 0.0806086
The difference 7.8602498
is the log. tang, of 2489196814, half the dif¬
ference of the angles CSB, CBS 5 therefore,
the angle CSB, that is the angle ACD, is
5489196814; and the angie CBS, that is
the angle BCD, is 5.0803186. Again, to
determine the angle CDS,
The log. tang, of half the angle
ACD is 7.8958249
The difference of the logs, of
AS, SP is 0.0806086
The difference 7.8152163
is the log. tang, of 228464 1426, half the
difference of the angles CSD, CDS ; there¬
fore
PHYSICAL and LITERARY. 133
fore the angle CDS, that is the angle DCF,
is 4/.Q95698 1.
Again, as the radius is to the fine of
5'.o8o3i86, fo is 57° 2997795, &c. the
number of degrees in an angle fubtended by
an arc equal to the radius, to the number of
degrees and minutes in an angle fubtended
by an arc equal to the fine of 5/.o8o3 186.
The log. of 570. 2957795 *s 1-7581226
The log. fine of 5'. 0803186 is 7.163331^
The fum is 8.92 14539
The log. of radius is io.oococoo
The difference —2.9214539
is the log. of 580073162, the number of
minutes contained in the angle A 5 the excefs
therefore of the angle BCD, above the angle
A, is 080930024. Again, as the fine of
the gngle BCD is to the tangent of the angle
DCF, fo is 080930024 to the angle DCG.
The log. of 080930024 is — 2.9684941
The log. tang, of the angle DCF is 7.1622795
The fum is 6.1307736
The log. fine of the angle BCD is 7*16333 13
Thp difference 2.9674423
134 ESSAYS and OBSERVATIONS
is the log. of ©'.0927774; the angle DCG
therefore is o’. 0927774 ; therefore the angle
ACG, the anomaly of the excentrie, is
55'.oi24588.
EXAMPLE III.
Supposing the mean anomaly in the fame
orbit to he 450, it is required to find the ano¬
maly of the excentrie.
The log. tang, of 220 30' is 9.6172243
The diff. of the logs, of AS, SP is 0.080608 5
The difference 9.5366158
is the log. tang, of 180 59.1327325, half the
difference of the angles CSB, CBS ; the
angle CSB, that is the angle ACD, therefore
is 410 29'. 1327325 ; and the angle CBS or
BCD is 30 30'. 8672675.
The log. tang, of half the angle
ACD is. 9*57^ 32°3
The diff. of the logs, of AS, SP is 0.080608 c
The difference 9.4977 118
is the log. tang, of 17*27.7082672, half
the difference of the angles CSD, CDS ;
the angle CDS or DCF, therefore, is
30 16', 858099=
i
PHYSICAL and LITERARY. 135
30 i6'.858o99. Again, as radius is to the
fine of the angle BCD, fo is 570. 2957795,
&c. to the angle A.
The log. of 570. 2957795, &c. is 1.7581226
The log. fine of the angle BCD is 8.7874623
The fum is 10.5455849
The log. of rad. is 10.0000006
The difference 0.5455849
is the log. of 30. 5122459; the angle A,
therefore, is 30 3o'.734754; the excefs of the
angle BCD above the angle A is o'. 13 25 13 5.
Again, as the fine of the angle BCD is to the
tangent of the angle SDC or DCF, fo is
o'.i325i35 to the angle DCG.
The log. of o'. 1 325 1 35 is —1.1222601
The log. tang, of the angle SDC is 8.7583537
The fum is 7.8806138
The log. fine of the angle BCD is 8.7874623
The difference — 1 .093 1515
is the log. of o'. 1239228; the angle DCG,
therefore, is o'.i239228 ; therefore the
angle ACGa the anomaly of the excentric, is
41° 29.2566553.
EX-
1 2 6 ESS AY S and OBSERVATIONS
EXAMPLE IV.
Again, in the fame orbit fuppofing the
mean anomaly to be ioo° degrees, it is re¬
quired to find the anomaly of the excentric.
The log. tang, of 50° half the
angle ACB is 10.0761865
The difference of the logs, of
AS, SP is 0.0806086
The difference 9*9955779
is the log. tang, of 44° 4284982 192, half the
difference of the angles CSB, CBS ; there¬
fore the angle CSB, that is the angle ACD,
is 940 4284982 192 3 and the angle CBS,
that is the angle BCD, is 50 1785017808.
Again, to determine the angle CDS*
The log. tang, of half the angle
ACD is 10.0557285'
The difference of the logs, of
AS, SP is 0.0806086
j r r.—l ' —
The difference 9.975 1199
is the log. tang, of 430 2185819834, half
the difference of the angles CSD, CDS 3
therefore the angle CDS, that is the angle
DCF, is 3° 5986671212.
Again,
PHYSICAL and LITERARY; 137
Again, as the radius is to the fine
of 50 1 7^50 17808 the angle BCD, fo is
570. 2997795 to the angle A.
The log* of 57°. 2957795 is 1.7581226
The log. fine of 50 17'. 5017808 is 8.964238 1
The fum is 10.7223607
The log. of radius is 10.0000000
The difference 0.7223607
is the log. of 50 166600752 the number of
degrees and minutes contained in the angle
A 5 the excefs therefore of the angle BCD
above the angle A is 069010288. Again,
as the fine of the angle BCD is to the tangent
of the angle DCF, fo is 069010288 to the
angle DCG.
The log. of 089010288 is — 1.9547387
The log. tang, of the angle DCF is 8.844043 1
The fum is 8.7987818
The log. fine of the angle BCD is 8.9642381
The difference —1.8345437
is the log. of o'. 683*934; the angle DCG
therefore is o'. 6831934; therefore the
angle ACG the anomaly of the excentrie is
940 4361814126.-
Vol. II. S
The
i38 ESSAYS and OBSERVATIONS
The three laft examples are taken from Dr.
Keif s aftronomical Ledtures, Lecture 23d.
and the numbers agree very nearly with his.
In the orbits of Mercury and Mars , if the
excels of the angle BCD above the angle A
be added to the angle ACD, the fum will be
nearly the anomaly of the excentrie reckoned
from the aphelion.
In orbits of fmall excentricity, the angle
ACD is nearly the anomaly of the excentrie ;
therefore the following rule will give the
anomaly of the excentrie very nearly.
From the logarithmic tangent of half the
mean anomaly, fubtradt the difference of the
logarithms of the aphelion and perihelion
diftances ; the remainder is the logarithmic
tangent of an angle, which call B : to the
angle B, add half the mean anomaly ; the^
fum will give very nearly the anomaly of the
excentrie.
EXAMPLE V.
In the earth’s orbit, the mean di fiance is
to the excentricity as 100000 to 1691. Sup-
pofe the mean anomaly from the aphelion
to be 30°, it is required to find the anomaly
of the excentrie.
The
PHYSICAL and LITERARY.
*39
The log. tang, of 15° is 9.4280525
The diff. of the logs, of AS, SP is 0.0146892
The difference 9.4133633
is the log. tang, of 14° 3L.3670421, half the
difference of the angles CSB, CBS ; there¬
fore the angle CSB, that is the angle ACD,
is 290 3 1'. 367042 ; therefore the anomaly of
the excentric is nearly 290 3i/.367042i, that
is 290 3 i'.22".o22526, which agrees very
nearly with Dr. KeiV s numbers in the
forefaid Ledhire,
EXAMPLE VI.
Again, in the earth’s orbit, fuppofe the
mean anomaly to be 6o°, it is required to find
the anomaly of the excentric.
The log. tang, of 30° is 9.7614394
The diff. of the logs, of AS, SP is 0.0146892
The difference 9.7467502
is the log. tang, of 290 io'.o8i873, half the
difference of the angles CSB, CBS ; there-
fore the angle CSB, that is the angle ACD,
is 590 io/.o8i873 ; therefore the anomaly of
the excentric is nearly 59° 10608 1873.
EX-
140 ESSAYS and OBSERVATIONS'
E X A M P L E VII,
In the orbit of Venus > the mean diftance is
to the excentricity as 10000000 to 69855.
Suppofe the mean anomaly reckoned from
the aphelion to be 6o°, it is required to find
the anomaly of the excentric.
The log. tango of 30° is 9.7614394
The diff. of the logs, of AS, SP is 0.00606 77
The difference 9-75537*7
is the log, tang, of 290 39^.2739959, half the
difference of the angles CSC, CBS ; therefore
the angle CSB, that is the angle ACD, is
590 3^.2739959 ; therefore the anomaly of
the excentric is nearly 590 39S2739959, that
is 590 39'. i6".439754.
If the mean anomaly reckoned from the
perihelion be 120°, the anomaly of the ex-
centric would be nearly 120° 20743" 560246,
which agrees very nearly with Mr. Machine
numbers in the forecited transaction.
The anomaly of the excentric being found,
the coequate or true anomaly will be found
by the relolution of the triangle GCS : Thus,
from the log. tang, of half the anomaly of
pmentric, fubtra<ff the difference of the
logs.
PHYSICAL and LITERARY.
141
logs, of the aphelion and perihelion diftances,
the remainder will be the log. tang, of an
angle ; to this angle add half the anomaly of
the excentric ; let the fain be called the
angle C ; to the log. tang, of the angle C,
add half the fum of the logs, of the aphelion
and perihelion diftances; from this fum, fub-
traCt the log. of the mean diftance ; the re¬
mainder will be the log. tang, of the coequate
or true anomaly.
Let CL be the leffer axis of the planet’s
orbit. Recaufe, from the nature of the
ellipfe, the fquare of CL is equal to the re¬
ctangle ASP, the log. of CL will be equal to
half the fum of the logs, of AS, SP : and, be-
caufe the tangent of the angle KSH is to the
tangent of the angle GSH as HK to HG ;
that is, from the nature of the ellipfe, as LC
to CA; therefore, if to the log. tang, of
the angle GSH, the log. of CL be added,
and from the fum the log. of AC be fub-
trafted, the remainder will be the log. tang,
of the angle KSH.
Again, the fine of the true anomaly is to
the fine of the anomaly of the excentric, as
the leffer axis of the orbit to the diftance of
the planet from the fun.
Because
142 ESSAYS and OBSERVATIONS
Because CL is to HK as CG to GH,
that is, as the radius to the fine of the ano¬
maly of the excentric, and HK is to KS as
the fine of the true anomaly to the radius ;
therefore CL is to KS as the fine of the true
anomaly to the anomaly of the excentric.
The place of a planet in an elliptic orbit
[granting the quadrature of the ellipfe] may be
found at any given time within a fmall limit,
by the following theorem.
THEORE M. Fig. 7.
Let the ellipfe, whole greater axis
is AP, foci S, K, and center C,
reprefent the orbit of a planet
round the fun at S; and, fuppofing
the periodic time of the planet
round the fun to be known, and
like ways the time the planet palled
thro" the aphelion A : As the pe¬
riodic time of the planet round
' the fun, is to the time elapfed
fmee the planet palled thro’ the
point
PHYSICAL and LITERARY. 143:
point A, i'o let the area of the el-
lipfe be to the lector ACB ; join
SB, and draw CD parallel to SB on
the lame fide of AP that SB is ;
and let CD be equal to CA ; join
SD; let CD, SD, meet the elliple in
E, F : the true place of the planet
is between the points E, F ; that
is, the planet is palled the point
E, but not come to the point F.
Let G be the place of the planet ; join
SG, and ioin BD meeting AP in H, and
join KB ; draw SL parallel to KB meeting
BD in L. Becaufe CD is parallel to SB,
CD will be to SB as CH to ITS ; therefore,
twice CD will be to SB as twice CH to HS.
But, becaufc twice CD is equal to AP, that
is, equal to KB together with BS, and twice
CH is equal to KH together with HS; there¬
fore KB together with, BS will he to BS as*
KH together with HS is to HS ; and there¬
fore KB will be to BS as KH to HS, that is,
as KB to SL; therefore BS, SL are equal:
therefore the angle SBL is equal to the angle
SLB,
144 ESSAYS and OBSERVATIONS
SLB, that is, equal to the angle KBD ; and
therefore, from a known property of the
ellipfe, BD is a tangent to the eilipfe at the
point R; and therefore \_Prop . 2.3 the fedor
ACB is greater than the fedor AS£> and lefs
than the fedor ASF : but, becaufe G is the
place of the planet, the area of the ellipfe
will be to the fedor ASG as the periodic
time of the planet round the fun is to the
time elapfed lince the planet paffed thro’ the
point A, that is, as the area of the ellipfe to
the fedor ACB ; therefore the fedor ASG
is equal to the fedor ACB ; and therefore
the fedor ASG is greater than the fedor
ASE, and lefs than the fedor ASF ; there¬
fore the line SG falls between the lines SE,
SF 5 and therefore G, the place of the planet,
is between the points E, F ; therefore the
planet has paffed the point E, but not come
to the point F,
1
Art,-
I
PHYSICAL and LITERARY* 145
Art. VII.
Of the Cold produced by Evaporating Fluids , and
of fome other Means of producing Cold ; by
Dr. William Cullen Profeffor of Me¬
dicine in the Univerfity of Glafgow^.
A Young Gentleman one of my pupils*
whom I had employed to examine the
heat or cold that might be produced by the
folution of certain fubftances in fpirit of wine*
obferved to me : That, when a thermometer
had been immerfed in fpirit of wine, tho’ the
fpirit was exactly of the temperature of the
furrounding air, or fome what colder ; yet,
upon taking the thermometer out of the
fpirit, and fufpending it in the air, the mer¬
cury in the thermometer, which was of Fa -
renheif s conftruftion, always funk two or
three degrees. This recalled to my mind
fome experiments and obfervations of M.
de Mairan to the fame purpofe 5 which I
had read fome time before. See Differtation
fur la glace , edit. 1749. pag . 248, & Jeq .
Vol. II. T When
* May 1. 1755.
'14.6 ESSAYS and OBSERVATIONS
When I firft read the experiments of M. de
Miaran in the place referred to, I fufpedted,
that water, and perhaps other fluids, in eva¬
porating, produced, or, as the phrafe is, gene¬
rated fome degree of cold. The above ex¬
periment of my Pupil confirmed my fufpi-
cion, and engaged me to verify it by a variety
of new trials.
I began by repeating the experiment with
fpirit of wine ; and found, when I had taken
the utmoft care to have the fpirit exactly of
the temperature of the air, that eonftantly
however, upon taking the thermometer out
of the fpirit, the mercury funk feveral de¬
grees, and indeed continued to fink fo long
as the ball of the thermometer continued wet
with the fpirit of wine. I found alfo, when
the ball began to dry, and the mercury to
rife again in the ftem of the thermometer,
that, if the ball was again dipped into the
fpirit and immediately taken out, the mer¬
cury in the thermometer might be again
obferved to fink, and that thus, by repeated
dippings, the cold produced might be ren¬
dered very remarkable. The cold produced
was alfo obferved to be ftill greater, when,
between each dipping, the thermometer was
moved
PHYSICAL and LITERARY. 147
moved very nimbly to and fro in the air ; or
if, while the ball was wet with fpirit of
wine, it was blown upon by a pair of bellows;
or indeed if the air about the ball was other-
wife any how put in motion. If any of thefe
means for putting the air in motion are em¬
ployed, the repeated moiftenings of the ball
of the thermometer may be performed by
dipping it into the fpirit of wine. But,
when a certain degree of cold has been
produced by a firft dipping, that is apt to be
diminifhed by dipping again into the warmer
fpirit ; and therefore the thermometer ought
either to be dipped into the fpirit and taken
out again very quickly, or, what is ftili better,
the ball of the thermometer ought to be moifb-
ened by a feather that has been dipped into
the fpirit of wine. By taking thefe methods,
I have by fpirit of wine made the mercury
in the thermometer fink from 44 degrees to
below the freezing point 5 and, by employing
fome other fluids to be mentioned by and
by, I have produced a finking of the thermo¬
meter much more confiderable.
In making experiments of this kind, it
is to be obferved, that the cold produced is
pf very fhort duration. On this account it
is
i48 ESSAYS and OBSERVATIONS
is not proper to employ a thermometer in-
clofed in a glafs tube; and it is neceffary to
employ one having a fmall ball, which may
render it more fenfible. But, as a fmall ball
occalions the divifions of the fcale to be the
fmaller, a thermometer filled with quick-
filver is not fo proper for thefe experiments,
as one filled with fpirit of wine ; having at
the fame time both a fmall ball and a {lender
Rem. What beft of all {hews the cold pro¬
duced, and is indeed, with relped: to feveral
fluids, quite necefiary, is an jltr thermometer.
This too will be rendered more convenient
by having the upper part of
the tube bent as in the figure
annexed, fo that the ball
may be moiftened without
the liquor's running down
upon the ftem and fcale,
I have entered into this detail for the fake of
tnofe who may deiire to repeat my experi¬
ments. Having now faid enough on the man-
fiei oi making them, I go on to obferve, that
in this way I have examined a great variety of
fluids. Such as?
The
PHYSICAL and LITERARY. 149
The quick- lime fpirit of fal. ammoniac ,
The aether of Frobenius,
The nitrous a then.
The volatile tinSlure of fulphur ,
Spirit of wine ,
Spirit of JaL ammoniac made with the fixed
alkali 5
. 'Brandy , - '
Winey
Vinegar ,
Water ,
0/7 0/ turpentine ,
0/7 */ mint ,
Oil of pimento .
By each of thefe employed to mol (ten the
ball of the thermometer, fome degree of cold
is produced. I dare not however at prefent
determine exa&ly what is the finking of the
thermometer produced by each. For this
purpofe, it would be neceffary to repeat the
trials often and with precifely the fame cir-
cumffcances at each time : which I find to be
very difficult* In the mean time I have
endeavoured to give a notion of the compara¬
tive power of thefe fluids in producing cold,
by the order in which I have fet them down;
having mentioned that fluid firfl: which
; ' * * . < a «. » •
feemed
1 5 9- ESSAYS and OBSERVATIONS
feemed to me to occafion the greateft finking
of the thermometer, and the reft follow in
order as they feemed to occafion lefs and
lefs.
From the above enumeration I imagine it
will appear, that the power of evaporating
fluids in producing cold, is nearly according
to the degree of volatility in each. If to this
we join the confideration, that the cold is
made greater by whatever haftens the eva¬
poration, and particularly, that the finking of
the thermometer is greater as the air in which
the experiment is made is warmer, if dry at
the fame time ; I think we may now con¬
clude, that the cold produced is the ejfeti of
evaporation,
I did not think it neceflary to diverfify my
experiments further by examining a great
many fluids, which are manifeftly of a like
nature with thefe above-mentioned. I pre-
fume pretty confidently, that the feveral fpi-
rituous, watery, and oily fluids, akin to thefe
already tried, will be found all of them to
have fimilar efifeds. And, confidering how
many fluids thefe clafles comprehend, and
that, in thefe already tried, the cold produced
feems to depend more on the volatility of the
aggregate
PHYSICAL and LITERARY. E^r
3ggregate than on the nature of the mixt^
I was ready to conclude, that all fluids what¬
ever, would, in evaporating, produce cold.
But I have found a feeming exception.
When the ball of the thermometer is
moiftened with any of the fofiil acids, a
confiderable degree of heat is produced. It
is however to be doubted, if this affords an
exception. We know that thefe acids attrad
water from the air ; and alfo that thefe acids,
mixed with water, always produce heat : it
may therefore be fuppofed, that the heat pro¬
duced, by moiftening the ball of the ther¬
mometer with thefe acids, is to be imputed
rather to their mixing with the water of -the
air, than to their evaporation fingly. This
perhaps cannot be pofitively determined, till
the evaporation of thefe acids, in a very per-
fed vacuum, is examined which I have not
yet had an opportunity of doing. In the
mean time, I have made an experiment
which I think is to the purpofe. To one
part of ftrong acid of vitriol, I added two
parts of fpring-water. When this mixture,
which produces a great degree of heat, was
returned to the temperature of the air, I ufed
it for moiftening the ball of the thermome-
ESSAYS and OBSERVATIONS
ter, and found it produced a fenfible degree
of cold, and feemingly a greater than water
alone would have done. I need not here
obferve, that the mixture I ufed was ftill a
Very acid liquor, only fo much faturated
with water, that it would not now attradt any
from the air. Whether it would not have
had the fame effedt, tho* lefs diluted, I have
not had time to examine. The experiment,
as it ftands, tends to prove, that the heat
produced by acids, applied to the ball of the
thermometer, is owing to the mixture of
thefe with the water of the air ; and there¬
fore, it is ftill very probable, that all fluids,
which do not immediately affedt the mixture
of the air, will, in evaporating, produce cold.
When I had proceeded thus far, I began
to confider, whether the cold produced in
the above experiments might not be the effedt
of the mixture of the feveral fluids with the
air 5 and that therefore, to a lift of cooling
mixtures and foiutions which I was then
making up, I fliould now add the feveral fo-
tions made by the air. By one who fuppofes
the evaporation of fluids to depend upon the
abtion of the air as a menftruum, this would
be readily admitted 3 but, as I knew that
fluids
PHYSICAL and LITERARY. iS3
fluids evaporate in vacuo as well as in the air,
I refolved to fufpend my opinion, till I
• fliould repeat my experiments in an ex-
haufted receiver.
In prolecuting thefe, a number of new
and to me curious phenomena have prefented
thernfelves ; fo many, that I find the experi¬
ments mull be often repeated, and much
diverfified, before I can give the Society a
proper account of them. In the mean time,
I fhall give you the following fads already
fufficiently verified.
A thermometer hung in the receiver of
an air-pump, finks always two or three de¬
grees upon the air's being exhaufted. After
a little time, the thermometer in vacuo re¬
turns to the temperature of the air in the
chamber, and upon letting air again into the
receiver, the thermometer always rifes two
or three degrees above the temperature of the
external air.
When a veflel containing fpirit of wine,
with a thermometer immerled in it, is fet
under the receiver of an air-pump ; upon
exhaufting the air, the mercury in the ther¬
mometer finks feveral degrees. It becomes
more efpecially remarkable when the air in
Vol. II. U any
*54 ESSAYS and OBSERVATIONS
any plenty iffues out of the fpirit of wine,
A$ the fpirit continues long to give out air,
fo it is long before the thermometer im-
merfed in it returns to the temperature of the
external air. But when after fome time it
appears ftationary, if it is then drawn up out
of the fpirits and fufpended in the vacuum,
the mercury finks very quickly eight or
nine degrees ; a good deal farther than it
would have done in the fame circumftances
in the air. In the fame manner as in the
air, the thermometer in *vacno may be
made ' to finkd lower by repeated dippings
into the fpirit of wine : but here thefe
repeated dippings have not fo remarkable
an effedt as in the air ; becaufe the dipping
cannot be fo quickly performed, and the
thermometer is therefore more affedled by
the warmth of the fpirit. It is fometimes
alfo affedted by a drop of the fpirit which
the ball takes up along with it, and which,
as I fhould have obferved above, ought al¬
ways to be taken away in the experiments
made in the air. This experiment with
fpirit of wine was often enough repeated, to
fhew clearly, that the evaporation of the fpirit
in ■
PHYSICAL and LITERARY.
i55
in vacuo prodaces a greater degree of cold
than the evaporation of the fame in the air.
Satisfied of this, I have tried alfo fome
other fluids, as the quick-lime fpirit of fal.
ammoniac, and the two kinds of aether.
VefTeis containing thefe with a thermometer
immerfed in the liquor, but feparately and at
different times, were fet under the receiver.
With regard to the different fluids, the phe¬
nomena were much the fame. Upon ex~
hau fling the receiver, the fluid gave out a
great quantity of elaftic air 5 and while this
happened, the mercury in the immerfed
thermometer funk very fafi: and to a great
length. In our trials, it generally funk below
the fcale applied fo that we could not
meafure exactly how far. In one experi¬
ment before exhaufting the receiver, the
thermometer had flood at 50 degrees, and*
after exhaufting, we could judge very cer¬
tainly that it funk to below 20. In another
j
experiment made with the nitrous aether,
when the heat of the air was about 53 de¬
grees, we fet the veffel containing the aether
in another a little larger containing water.
Upon exhaufting the receiver, and the veflefs
remaining for a few minutes in vacuo* we
found
1 56 ESSAYS and OBSERVATIONS
found the moft part of the water frozen, and
the veffel containing the asther iurrounded
with a thick and firm cruft of ice.
Such a means of producing cold, and to
fo great a degree, has not, fo far as I know,
been obferved before, and it feems to deferve
being further examined by experiments.
Till that is done, I do not chufe to give any
account of fome other remarkable phenomena
that have occurred in the above experiments,
nor to enter into the feveral fpeculations that
the fubjedt feems to fuggeft.
Since writing the above, I have had occa-
fion to obferve, that Mr. Kick-man of the A-
cadamy of Peterjburg has taken notice of the
effedl of evaporating fluids in producing cold;
but does not impute it to the evaporation
alone. His very exadt account of th e pheno¬
mena , and his theory with regard to them,
may be feen in Nov . Comment . Acad . Petropo -
Utance ad ami, 174 7 & 1748. page 284.
Art.
/
PHYSICAL and LITERARY. 157
Art. VIII.
Experiments upon Magndia alba, Quicklime ,
and fome other Alcaline Subjiances $ by
Joseph Black, M, D. *
t
Part I.
i
HOFFMAN , in one of his obferva-
tions, gives the hiftory of a powder
called magnejia alba , which had been long
ufed and efteemed as a mild and taftelefs
purgative 3 but the method of preparing it
was not generally known before he made it
public ‘f*.
It was originally obtained from a liquor
called the mother of nitre , which is produced
in the following manner :
Salt-petre is feparated from the brine
which fir ft affords it, or from the water
with which it is wafhed out of nitrous earths,
by the procefs commonly ufed in cryftallizing
falts. In this procefs the brine is gradually
diminifhed, and at length reduced to a fmall
quantity of an undtuous bitter faline liquor,
affording
* June 5- 175?*
■f Hoff. op. T. iv. p. 479.
x58 ESSAYS and OBSERVATIONS
affording no more falt-petre by evaporation ;
but, if urged with a brifk fire, drying up into
a confufed mafs which attracts water ftrongly,
and becomes fluid again when expofed to the
open air„
To this liquor the workmen have given
the name of the mother of nitre \ and Hof man,
finding it compofed of the magnefia united to
an acid, obtained a feparation of thefe, either
by expofing the compound to a ftrong fire in
which the acid was diflipated and the magne-
Jia remained behind, or by the addition of an
alkali which attracted the acid to itlelf : and
this laft method he recommends as the befL
He like wife makes an inquiry into the nature
and virtues of the powder thus prepared ; and
obferves, that it is an abforbent earth which
joins readily with all acids, and mu ft ne-
ceffarily deftroy any acidity it meets in the
ftomach ; but that its purgative power is un¬
certain, for fometimes it has not the leaft
effect of that kind. As it is a mere infipid
earth, he rationally concludes it to be pur¬
gative only when converted into a fort of
neutral fait by an acid in the ftomach, and
that its effect is therefore proportional to the
quantity of this acid.
Althq*
PHYSICAL and LITERARY. 15?
Alt ho' magnejia appears from this hiftory
of it to be a very innocent medicine, yet
having obferved, that feme hypochondriacs
who ufed it frequently, were fubjed to flatu¬
lencies and fpafms, he feems to have fufpeded
it of feme noxious quality. The circum-
ftances however which gave rife to his fufpi-
cion, may very poffibly have proceeded from
the imprudence of his patients, who, trailing
too much to magnejia , (which is properly a
palliative in that difeafe,) and negleding the
affiftance of other remedies, allowed their
difcrder to increafe upon them. It may in¬
deed be alledged, that magnejia , as a purga¬
tive, is not the molt eligible medicine for
fuch conftitutions, as they agree bell with
thofe that ftrengthen, ftimulate and warm ;
which the faline purges commonly ufed are
not obferved to do. But there feems at leaf:
to be no obiedion to its ufe when children
are troubled with an acid in their ftomachj
for gentle purging in this cafe is very proper,
and it is often more conveniently procured by
means of magnejia than of any other medicine,
on account of its being intirely infipid.
The above-mentioned Author obferving*
feme time after, that a bitter faline liquor,
fimilar
«
| So ESSAYS and OBSERVATIONS
fimiiar to that obtained from the brine of
fait-petre, was like wife produced by the
evaporation of thofe waters which contain
common fait, had the curiofity to try if this
would alfo yield a magnejia . The experi¬
ment fucceeded : and he thus found out
another procefs for obtaining this powder,
and at the fame time allured himfelf by ex¬
periments, that the produd from both was
exadly the fame
My curiofity led me fome time ago to in¬
quire more particularly into the nature of
magnejia , and efpecially to compare its pro¬
perties with thofe of the other abforbent
earths, of which there plainly appeared to me
to be very different kinds, altho’ commonly
confounded together under one name. I
was indeed led to this examination of the
abforbent earths, partly by the hope of dis¬
covering a new fort of lime and lime-water,
which might poffibly be a more powerful
folvent of the ftone than that commonly
ufed; but was difappointed in my expecta¬
tions.
I have had no opportunity of feeing Hoff-
mans firft magnejia or the liquor from which
it
* Hoff. Op. T. iv. p. 500.
PHYSICAL and; LITER ARY. :l6i
f x r T * ,a r *r
it is prepared, and have therefore been
obliged to make my experiments upon the
fecond.
In order to prepare it, I at firfi employed
the bitter faline liquor called bittern , which
remains in the pans after the evaporation of
fea water. But as that liquor is not always
eafily procured, I afterwards made ufe of a
fait called epfom-jalt , which is feparated from
the bittern by cryftallization, and is evidently
compofed of magnejia and the vitriolic acid.
There is likewile a fpurious kind of
Glauber fait, which yields plenty of magnejia ,
and feems to be no other than the epfom fait
of fea water reduced to cryftals of a larger
fize. And common fait alfo affords a fmall
. * ”* k ' t ■ i- i
quantity of this powder 3 becaufe being fepa¬
rated from the bittern by one hafty cryftalli¬
zation only, it neceffarily contains a portion
of that liquor.
I hose who would prepare a magnejia from
epfom-^alt, may ufe the following procefs.
Dissolve equal quantities of epfbm-falt,
and of pearl allies feparately in a fufficient
quantity of water; purify each folution from
its dregs, and mix them accurately together
Vol. IL X ' by
1 62 ESSAYS AND OBSERVATIONS
* * ‘ % ' 1 '* \ 41 V
by violent agitation: then make them juft to
boil over a brilk fire.
Add now to the mixture three or four
times its quantity of hot water ; after a little
agitation, allow the magnefia to fettle to the
bottom, and decant off as much of the water
as poflible. Pour on the fame quantity of
cold water ; and, after fettling, decant it off
in the fame manner. Repeat this wafhing
with the cold water ten or twelve times : or
■ \ y . « * 0 t A 1 +•* * *• ■*>**• ■**-■* • • * 4 * v
even oftner, if the magnefia be required per¬
fectly pure for chemical experiments.
When it is fufficiently wafhed, the water
may be ftrained and fqueezed from it in a
linen cloth ; for very little of the magnefia
pafles throb
The alkali in the mixture uniting with the
acid, feparates it from the magnefia ; which not
being of itfelf foluble in water, mult conse¬
quently appear immediately under a folid form.
But the powder which thus appears is not
intirely magnefia j part of it is the neutral fait,
formed from the union of the acid and alkali.
This neutral fait is found, upon examination,
to agree in all refpeCts with vitriolated tartar,
and requires a large quantity of hot water to
diflolve it. As much of it is therefore dif-
folved
PHYSICAL and LITERARY. 163 1
folved as the water can take up; the reft is
difperfed thro’ the mixture in the form of a
•powder. Hence the neceffity of wafhing the
magnefia with fo much trouble ; for the fir ft
affufion of hot water is intended to diffolve
the whole of the fait, and the fubfequent ad¬
ditions of cold water to waih away this fo-
lution. - -
The caution given of boiling the mixture is
not unneceftary; if it be neglected, the whole
of the magnejia is not accurately Yeparated at
once ; and by allowing it to reft for fome
time, that powder concretes into minute
grains, which, when viewed with the mi-
crofcope, appear to be aflemblages of needles -
diverging from a point. This happens more
efpecially when the folutions of the epfom-
falt and of the alkali are diluted with too
much water before they are mixed together.
Thus, if a dram of epfom-falt and of fait of
tartar be diffolved each in four ounces .of 2
water, and be mixed, and then allowed to reft ;
three or four days, the whole of the magnefia
will be formed into thefe grains. Or if we
filtrate the mixture foon after it is made, and
heat the clear liquor which paffes thro’ ; it
will become turbid, and depofite a magnefia* *
I
? 64 ESSAYS and OBSERVATIONS
I had the curiofity to fatisfy myfelf of the
purgative power of magnefia , and of Hoffman s
opinion concerning it, by the following eafy
experiment. I made a neutral fait of magnefia \
and diftilled vinegar ; choofing this acid as
being, like that in weak ftomachs, the product
of fermentation. Six drams of this I di'f-
fblved in water, and gave to a -middle-aged
man, de firing him to take it by degrees.
After having taken about a third, he deiifted,
and purged four times in an eafy and gentle
manner. A woman of a ftrong conftitution
got the remainder as a brifk purgative, and
it operated ten times without caufing any un-
eafinefs. The tafte of this fait is not dis¬
agreeable, and it appears to be rather of the
cooling than of the acrid kind.
Having thus given a Abort fketch of the
hiftory and medical virtues of magnefia , I
now proceed to an account of its chemical
properties. By my firft experiments, I in- .
tended to learn what fort of neutral falts
might be obtained by joining it to each of
the vulgar acids ; and the refult was as
follows.
Magnesia is quickly diifolved with vio- ..
lept effervefcence, or explofion of air, by the
acids
V • V \ • \
PHYS ICAL and LITER ARY. 165
acids of vitriol, nitre, and of common fait,
*
and by diftilled vinegar 3 the neutral faline
liquors thence produced having each their
peculiar properties,
That which is made with the vitriolic
acid, may be condenfed into cryftals fimilar
in all refpefts to epfom-falt.
That which is made with the nitrous
is of a yellow colour, and yields faline
cryftals, which retain their form in a very
dry air, but melt in a moift one.
That which is produced by means of
fpirit of fait, yields no cryftals; and if eva¬
porated to drynefs, foon melts again when ex-
pofed to the air.
That which is obtained from the union
of diftilled vinegar with magnejia , affords no
cryftals by evaporation, but is condenfed
into a faline mafs, which, while warm, is
extremely tough and vifcid, very much re-
fembling a ftrong glue both in colour and
confidence, and becomes brittle when cold.
* •
By thefe experiments magnejia appears to
be a fubftance very different from thofe of
the calcarious clafs ; under which I would
be underftood to comprehend all thofe that
$re converted into a perfect quick-lime in a
ftrqng
1 66 ESSAYS and OBSERVATIONS
ftrong fire, fuch as lime-ftone , marble , chalk,
thofe /pars and marles, which efFervefce
with aqua fortis, all animal Jhelh and the
bodies called lithophyta . All of thefe, by
being joined* with acids, yield a fet of
compounds which are very different from
thofe we have juft now defcribed Thus, if
a fmall quantity of any calcarious matter be
reduced to a fine * powder and thrown into
fpirit of vitriol, it is attacked by this acid
with a brifk effervefcence ; but little or no
diffolution enfues. It abforbs the acid, and
remains united with it in the form of a
white powder, at the bottom of the veffel,
while the liquor has hardly any tafte, and
fhews only a very light cloud upon the addi¬
tion of an alkali*.
The fame white powder is alfo formed
when fpirit of vitriol is added to a calca-
carious earth diffolved in any other acid j
the vitriolic expelling the other acid, and
joining
* Mr. Margraaf has lately demonftrated, byafet of curious
and accurate experiments, that this powder is of the nature,
and poffefTes the properties, of the gypfeous or felenitic fub-
ftances. That fuch fubflances can be refolved into vitriolic
acid and calcarious earth, and can be again compofed by-
joining thefe two ingredients together, Mem de 1’Acad, de
Berlin, an. 175c, p. 144.
PHYSICAL and LITERARY. 167
joining itfelf to the earth by a ftronger attra¬
ction ; and upon this account the magnejia of
Tea- water feems to be different from either of
thofe defcribed by Hoffman . He fays ex-
prefsly, that the folutions of each of his pow¬
ders, or, what is equivalent, that the liquors
from which they are obtained, formed a
coagulum, and depofited a white powder,
when he added the vitriolic acid*; which
experiment I have often tried with the
marine bittern, but without fuccefs. The
coagulum thus formed in the mother of
nitre may be owing to a quantity of quick¬
lime contained in it 3 for quick-lime is ufed
in extracting the falt-petre from its matrix.
But it is more difficult to account for the dif¬
ference between Hoffman s bittern and ours,
unlefs we will be fatisfied to refer it to this,
that he got his from the waters of fait fprings,
which may poffibly be different from thofe
of the fea.
Magnesia is not lefs remarkably diftin-
guiffied from the calcarious earths, by joining
it to the nitrous and vegetable acids, than to
the vitriolic. Thofe earths, when combined
with fpirit of nitre, cannot be reduced to a
cryftalline
J
* Hoff. Op. T, iv. p, 480 & 500.
1 6$ -ESSAYS and OBSERVATIONS
cryflalline form, and if they are diflblved in
diftilled vinegar, the mixture fpontaneoufly
dries up into a friable fait.
Having thus found magnefia to differ
from the common alkaline earths, the objeCt
of my next inquiry was its peculiar degree of
attraction for acids, or what was the place
due to it in Mr. Geoffroy s table of eledtive
attractions*
Three drams of magnejia in fine powder,
an ounce of fait ammoniac, and fix ounces
of water were mixed together, and digefted
fix days in a retort joined to a receiver.
During the whole time, the neck of the
retort was pointed a little upwards, and the
moft watery part of the vapour, ; which was
condenfed there, fell back into its body. In
the beginning of the experiment, a volatile
fait was therefore collected in a dry form in
the receiver, and afterwards diflblved into
fpirit.
When all was cool, I found in the retort
a faline liquor, fome undiflolved magnejia , and
fome fait ammoniac cryftallized. The faline
liquor was feparated from the other two, and
then mixed with the alkaline fpirit. A
coagulum
PHYSICAL and LITERARY, 1 6g
coagulum was immediately formed, and a
magnefia precipitated from the mixture.
The magnefia which had remained in the
retort, when well wafhed and dried, weighed
two fcruples and fifteen grains.
W e learn by the latter part of this experi¬
ment, that the attraction of the volatile alkali
for acids is ftronger than that of magnefia ,
fince it feparated this powder from the acid
to which it was joined. But it alfo appears,
that a gentle heat is capable of overcoming
this fuperiority of attraction, and of gradually
elevating the alkali, while it leaves the lefs
volatile acid with the magnefia .
Dissolve a dram of any calcarious fub-
ftance in the acid of nitre or of common fait,
taking care that the folution be rendered per¬
fectly neutral, or that no fuperfiuous acid be
added. Mix with this folution a dram of
magnefia in fine powder, and digeft it in the
heat of boiling water about twenty four
hours j then dilute the mixture with double
its quantity of water, and filtrate. The
greateft part of the earth now left in the
filtre is calcarious, and the liquor which
paffed thro’, if mixed with a diffolved alkali,
Vol. II. \ yields
i7o ESSAYS and OBSERVATIONS
'Sb '
yields a white powder, the largeft portion of
which is a true magnejia .
From this experiment it appears, that an
acid quits a calcarious earth to join itfelf to
magnefia ; but the exchange being performed
flowly, fome of the magnefia is ftill un-
dilfolved, and part of the calcarious earth
remains yet joined to the acid.
When a fmall quantity of magnejia is
thrown into a folution of the corrofive fubli-
mate of mercury, it foon feparates part of the
mercury in the form of a dark red powder,
and is itfelf diflblved.
Imagining that I perceived fome refem-
blanee between the properties of magnejia
and thofe of alkalis, I was led to try what
change this fubftance would fuffer from the
addition of quick-lime, which alters in fuch a
peculiar manner the alkaline falts.
Twenty feven grains of magnejia in fine
powder were mixed with eighteen ounces of
lime-water in a flafk, which was corked clofe
and fhaken frequently for four days. During
this time, I frequently dipp’d into it little
bits of paper, which were coloured with the
juice of violets ; and thefe became green as
foon as they touched the water, until the
fourth
PHYSICAL and LITERARY. 171
fourth day, when their colour did not feem
to be altered. The water being now poured
off, was intirely infipid, and agreed in every
chemical trial with pure water. The» pow¬
der, after being perfectly well dried, weighed
thirty feven grains. It did not diffolve intirely
in fpirit of vitriol ; but, after a brifk effer^-
vefcence, part of it fubfided in the fame man¬
ner as the calcarious earths, when mixed
with this acid. . -
When I firft tried this "experiment, ‘ Lwas
at the trouble of digefting the mixture in the
heat of boiling water, and did not then know
that it would fucceed in the heat of the
air. But Dr . Alftm, who has obliged the
world with many curious and ufeful difco-
veries on the fubjeCt of quick-lime, having
had occaiion to repeat it, I learned from him
that heat is not neceffary ; and he has more¬
over added an ufeful purpofe to which this
property of fnagnejia may be applied ; X mean
the fweetening of water at fea, with which
lime may have been mixed to prevent its pu¬
trefaction.
That part of the dried powder. ‘'which
does not diffolve in fpirit of vitriol, confifts of
the lime feparated from the water. : :r
Quick-lime
172 t< s s A.'y s and OBSERVATIONS
Quick -lime itfe-lf is alfo rendered mild
by magnefia^ if thefe two are well rubbed
together and infufed with a fmall quantity of
water.
By the following experiments, I propofed
to know whether this fubftance could be re¬
duced to a quick-lime.
An ounce of magnejia was expofed in a
crucible for about an hour to fueh a heat as
is fufhcient to melt copper. When taken
out, it weighed three drams and one fcruple,
or had loft T7T of its former weight.
I repeated, with the magnejia prepared in
this manner, moft of thofe experiments
I had already made upon it before calcina¬
tion, and the refult was as follows.
It diftolves in all the acids, and with thefe
compofes felts exadlly fimilar to thofe de-
fcribed in the firft fet of experiments : but
what is particularly to be remarked, it is dif-
folved without any the leaft degree of effer-
vefcence.
It flowly precipitates the corrofive fub-
limate of mercury in the form of a black
powder.
It feparates the volatile alkali in felt am-
pioruac from the acid, when it is mixed
with
PHYSICAL and LITERARY. 173
with a warm folution of that fait. * But it
does not feparate an acid from a calcarious
earth, not does it induce the leaft change
upon lime-water.
Lastly, when a dram of it is digefted
with an ounce of water in a bottle for fome
hours, it does not make any the leaft change
in the water. The magnefia , when dried, is
found to have gained ten grains 3 but it nei¬
ther effervefces with acids, nor does it fen-
fibly affedt lime-water.
Observing magnefia to lofe fuch a re-
markable proportion of its weight in the fire,
my next attempts were directed to the in-
veftigation of this volatile part, and, among
other experiments, the following feemed to
throw fome light upon it.
Three ounces of magnefia were diftilled in
a glafs retort and receiver, the fire being
gradually increafed until the magnefia was
obfcurely red hot. When all was cool, I
found only five drams of a whitifh water in
the receiver, which had a faint fmell of the
fpirit of hartfhorn, gave a green colour to the
juice of violets, and rendered the folutions of
corrofive fublimate and of filver very flightly
turbid.
i-4 ESSAYS and OBSERVATIONS
turbid. But it did not fenfibly effervefce with
acids. ,
The magnefia , when taken out of the re¬
tort, weighed an ounce, three drams, and
thirty grains, or had loft more than the half
4 , J J O 1 -
*■ j _
of its weight. It ftill effervefced pretty brilk-
ly with acids, tho’ not fo ftrongly as before
this operation.
The fire fhould have been raifed here to
the degree requifite for the perfect calcinati¬
on of magnefia . But even from this imper¬
fect experiment, it is -evident, that of the vo¬
latile parts contained in that powder, a final!
proportion only is water 5 the reft cannot, it
feerns, be retained in vefiels, under a vifible
form. Chemifts have often observed, in their
diftillations, that part of a body has vanifhed
from their fenfes, notwithstanding the utmoft
care to retain i t; and they have always found,
c " 1 * ’ \
upon further inquiry, that fuhtile part to be
air, which having been imprifoned in the
body, under a folid form, was fet free and
rendered fluid and elaftic by the fire. We
may therefore fafely conclude, that the vola¬
tile matter, loft in the calcination of magnefia ,
is inoftly air y and hence the calcined mag-
• f ; , nefia
PHYSICAL and LITERARY. 175
nejia does not emit air, or make an effervef-
eence, when mixed with acids.
The water, from its properties, feems to
contain a fmall portion of volatile alkali,
which was probably formed from the earth,
air, and water, or from fome of thefe com*
bined together ; and perhaps alfo from a
fmall quantity of inflammable matter which
adhered accidentally to the magnefia . When¬
ever Chemifts meet with this fait, they are
inclined to afcribe its origin to fome animal,
or putrid vegetable, fubftance 5 and this they
have always done, when they obtained it
from the calcarious earths, all of which af¬
ford a fmall quantity of it. There is, how-'
ever, no doubt that it can fometimes be pro¬
duced independently of any fuch mixture,
fince many frefh vegetables and tartar afford a
confiderable quantity of it. And how can
it, in the prefent inftance, be fuppofed, that
any animal or vegetable matter adhered to the
magnefia , while it was diffolved by an acid,
feparated from this by an alkali, and waffl¬
ed with fo much water ?
Two drams of magnefia were calcined in a
crucible, in the manner defcribed above, and
thus reduced to two fcruples and twelve
grains.
1 76 ESSAYS and OBSERVATIONS
grains. This calcined magnefia was difiolved
in a fufficient quantity of fpirit of vitriol, and
then again feparated from the acid by the ad¬
dition of an alkali, of which a large quanti¬
ty is necelTary for this purpofe. The mag-
nefia being very well wafhed and dryed,
weighed one dram and fifty grains. It effer-
vefced violently, or emitted a large quantity
of air, when thrown into acids, formed a red
powder when mixed with a folution of fub-
limate, feparated the calcarious earths from
an acid, and fweetened lime-water : and had
thus recovered all thofe properties which it
had but juft now loft by calcination: nor
had it only recovered its original properties,
but acquired befides an addition of weight
nearly equal to what had been loft in the fire;
and, as it is found to effervefce with acids,
part of the addition muft certainly be air.
This air feems to have been furnifhed by
the alkali from which it was feparated by
the acid ; for Dr. Hales has clearly proved,
that alkaline falts contain a large quantity of
fixed air, which they emit in great abundance
when joined to a pure acid. In the prefent
cafe, the alkali is really joined to an acid, but
without any vifible emiffion of air ; and yet
the
PHYSICAL and LITERARY. 177
the air is not retained in it : for the neutral
fait, into which it is converted, is the fame
-in quantity, and in every other refpedt, as if"
the acid employed had not been previoufly
faturated with magnefia , but offered to the
alkali in its pure Rate, and had driven the
*
air out of it in their conflict. It feems there¬
fore evident, that the air was forced from
the alkali by the acid, and lodged itfelf in the
magnefia .
These confiderations led me to try a few
experiments, whereby I might know what
quantity of air is expelled from an alkali, or
from magnefia , by acids.
Two drams of a pure fixed alkaline fait,
and an ounce of water, were put into a Floren¬
tine flafk, which, together with its contents,
weighed two ounces and two drams. Some
oil of vitriol diluted with water was dropt in,
4
until the fait was exactly faturated ; which it
was found to be, when two drams, two fcru-
ples, and three grains of this acid had been
added. The vial with its contents now
weighed two ounces, four drams, and fif¬
teen grains. One fcruple, therefore, and
eight grains were loft during the ebullition,
of which a trifling portion may be water, or
Vol. II. Z fomething
iT8' ESSAYS and OBSERVATION S:
fomething of the fame kind. The reft is5
air.
The celebrated Homberg has attempted to
** /
eftimate the quantity of fo-lid fait contained
in a determined portion of the feveral acids.
He faturated equal quantities of an alkali with
each of them ; and, obferving the weight
which the alkali had gained, after being per¬
fectly dryed, took this for the quantity of fo-
lid fait contained in that fhare of the acid
which performed the faturation. But we
learn from the above experiment, that his efti¬
mate was not accurate, becaufe the alkali lofes
weight as well as gains it.
Two drams of magnejiar treated exaCtly
as the alkali in the laft experiment, were juft
diffolved by four drams, one fcruple, and fe-
ven grains of the fame acid liquor, and loft
one fcruple and fixteen grains by the ebulli¬
tion.
Two drams of magnejia were reduced, by
the aCtion of a violent fire, to two fcruples
and twelve grains, with which the fame pro-
cefs was repeated, as in the two laft expe¬
riments 5 four drams, one fcruple, and two
grains of the fame acid were required to com-
pleat
PHYSICAL and LITERARY. 17^
pleat the foliation, and no weight was loft in
the experiment.
As in the reparation of the volatile from
the fixed parts of bodies, by means of heat,
a fmali quantity of the latter is generally rai¬
led with the former; fo the air and water, .0-
riginally contained in the magnefia , and after¬
wards' diffipated by the fire, feem to have
carried oft a fmali part of the fixed earth of
this fubftance. This is probably the rea-
fon, why calcined magnefia is Saturated with
a quantity of acid, fomewhat lefs than what
is required to diftblve it before calcination :
and the lame may be affigned as one caufe
which hinders us from reftoring the whole of
its original weight, by foiutipn and precipita¬
tion.
I took care to dilute the vitriolic acid, in
order to avoid the heat and ebullition which
it would otherwife have excited in the water ;
and I chofe a Florentine flafk, on account of
its lightnefs, capacity, and fhape, which is
peculiarly adapted to the experiment ; for
the vapours raifed by the ebullition circulated
for a fhort time, thro' the wide cavity of the
vial, but were foon collected upon its fides,
like dew, and none of them feemed to reach
the
28 o ESSAYS AND OBSERVATIONS
the neck, which continued perfectly dry tq
the end of the experiment.
We now perceive the reafon, why crude
and calcined magnejia , which differ in many
refpeds from one another, agree however in
compofing the fame kind of fait, when dif-
folved in any particular acid ; for the crude
magyiefia feems to differ from the calcined
chiefly by containing a confiderable quantity
of air, which air is unavoidably diffipated
and loft during the diflolutipn.
From our experiments, it feems probable,
that the increafe of weight which fome me”
tals acquire, by being firft diffolved in acids,
and then feparated from them again by alkalis,
proceeds from air furnifhed by the alkalis.
And that in the aurum fulminans , which is pre¬
pared by the fame means, this air adheres to
the gold in fuch a peculiar manner, that, in
a moderate degree of heat, the whole of it
recovers its elafticity in the fame inftant of
time ; and thus, by the violent fhock which
" ; , * - ' ' • *
it gives to the air around, produces the loud
crack or Elimination of this powder. Thofe
who will imagine the explcflon of fuch a mi¬
nute portion of fixed air, as can refide in the
mrum fulminans , to be infufficient for the
t V • '» ■ ; * v >/. , '* __
exceffive
PHYSICAL and LITERARY. 18*
cxceffive loudnefs of the noife, will confi-
der, that it is not a large quantity of motion
communicated to the air, but rather a fmart
flroke which produces found, and that the ex-
plofion of but a few particles of fixed air tpay
be capable of caufing a loud noile, provided
they all recover their fpring fuddenly, and in
the fame inftant.
The above experiments lead us alfo to
conclude, that volatile alkalis, and the com¬
mon abforbent earths, which lofe their air
by being joined to acids, but (hew evident
figns of their having recovered it, when fe-
parated from them by alkalis, received it from
thefe alkalis which loft it in the inftant of
their joining with the acid.
The following are a few experiments upon
three of the abforbent earths, made in order
to compare them with one another, and with
magnejia .
Sufpeding that magnefa might poflibly be
no other than a common calcarious earth,
* ' » .
which had changed its nature, by having been
previoufly combined with an acid, I fatura-
ted a fmall quantity of chalk with the muria¬
tic acid, feparated the acid from it again by
means
1*2 ESSAYS AND OBSERVATIONS
means of a fixed alkali, and carefully walk¬
ed away the whole of the fait.
The chalk when dryed was not found to
have fuffered any alteration 3 for it efFervef-
ced> with the vitriolic acid, but did not diffolve
in it 3 and when expofed to a violent fire,
was converted into a quick- lime, in all re-
fpeds fimilar to that obtained from common
chalk.
In another experiment of the fame kind,
I ufed the vitriolic acid with the fame event.
Any calcaneus matter reduced to a fine
powder, and thrown into a warm folution of
alum, immediately raifes a brifk effervefcence.
But the powder is not diffolved 3 it is rather
increafed in bulk : and if the addition be re¬
peated until it is no longer accompanied with
effervefcence, the liquor lofes all tafie of the
alum, and yields only a very light cloud upon
the admixture of an alkali.
From this experiment we learn, that acids
attrad the calearious earths more ftronglv
than they do the earth of alum 3 and as the
j
acid in this fait is exadly the fame with the
vitriolic, it compofes with the calearious
earth a neutral fubftance, which is very diffi¬
cultly foluble in water, and therefore falls;
down
PHYSICAL and LITERARY. 185
down to the bottom of the veffel along with
the earth of alum which is deprived of its
acid. The light cloud formed by the alkali
proceeds from the minute portion of the
calcarious compound which fat urates the
water.
The earth of animal bones, when reduced
to a fine powder and thrown into a diluted
vitriolic acid, gradually abforbs the acid in
the fame manner as the calcarious earths,
but - without any remarkable effiervefcence.
When it is added to the nitrous or to the
muriatic acid, it is flowly difiblved. The
compound liquor thence produced is ex¬
tremely acrid, and (till changes the colour of
the juice of violets to a red, even after it is
fully faturated with the abforbent. Diftilled
vinegar has little or no effedt upon this earth.;
for after a long digeftion it ftill retains its
four tafte, and gives only a light cloud upon
the addition of an alkali.
By dropping a difiblved fixed alkali into a
warm folution of alum, I obtained the earth
of this fait, which, after being well wafhed
and dried, was found to have the following-
properties.
It
I
184 ESSAYS and OBSERVATIONS
It is diffolved in every acid but very
flowly, unlefs affifted by heat. The feverai
folutions, when thoroughly faturated, are all
adringent with a flight degree of an acid
tade, and they alfo agree with a folution of
alum in this, that they give a red colour to
the infufion of turnfol.
Neither this earth, nor that of animal
bones, can be converted into quick-lime by
the ftronged fire, nor do they fuffer any
change worth notice. Both of them feem to
attract acids but weakly, and to alter their
properties lefs when united to them than the
other abforbents.
Part II.
IN refleding afterwards upon thefe expe¬
riments, an explication of the nature of
lime offered itfelf, which feemed to account*
in an eafy manner, for mod of the proper¬
ties of that fubdance.
It is fufHciently clear, that the calcarious
earths in their native date, and that the
alkalis and magnefia in their ordinary condi¬
tion, contain a large quantity of fixed air, and
this
PHYSICAL and LITERARY. 185
this air certainly adheres to them with confi-
derable force, fince a ftrong fire is necefiary
to feparate it from magnefia, and the ftrongefl
is not fufficient to expell it entirely from fixed
alkalis, or take away their power of effervef-
cing with acid falts.
These confederations led me to conclude,
that the relations between fixed air and ah
kaline fubftances was fomewhat fimilar to the
relation between thefe and acids ; that as the
calcarious earths and alkalis attradl acids
ftrongly and can be faturated with them,
fo they alfo attract fixed air, and are in their
ordinary Rate faturated with it : and when we
mix an acid with an alkali or with an abfor-
bent earth, that the air is then fet at liberty,
and breaks out with violence; becaufe the al¬
kaline body attracts it more weakly than it does
the acid, and becaufe the acid and air cannot
both be joined to the fame body at the fame
time.
I alfo imagined, that, when the calcarious
earths are expofed to the adlion of a violent
fire, and are thereby converted into quick¬
lime, they fuffer no other change in their
compofition than the lofs of a fmall quantity
of water and of their fixed air. The re-
Vol. II. A a markable
186 ESSAYS and OBSERVATIONS
- .. . *■ ^
markable acrimony which we perceive in
them after this procefs, was not fuppofed to
proceed from any additional matter received
in the fire, but feemed to be an effential pro¬
perty of the pure earth, depending on an
attraction for thole feveral fubflances which
it then became capable of corroding or dif-
folving, which attraction had been infenfible
as long as the air adhered to the earth, but
difcovered itfelf upon the feparation.
This fuppofition was founded upon an ob-
fervation of the mod frequent confequences
of combining bodies in chemiftry. Com¬
monly when we join two bodies together,
their acrimony or attraction for other fub¬
flances becomes immediately either lefs per¬
ceivable or entirely infenfible ; altho’ it wasr
fufficiently ftrong and remarkable before
their union, and may be rendered evident
again by disjoining them. A neutral fait,
which is compofed of an acid and alkali, does
not poffefs the acrimony of either of its con-
ftituent parts. It can eafily be feparated from
water, has little or no efFeCt upon metals, is
incapable of being joined to inflammable
bodies, and of corroding and diflfolving ani¬
mals and vegetables ; fo that the attradion
both of the acid and alkali for thefe feveral
fobftances
PHYSICAL and LITERARY. 187
fubftances feems to be fufpended till they are
again feparated from one another.
Crude lime was therefore confidered as a
peculiar acrid <earth rendered mild by its
union with fixed air : and quick-lime as the
fame earth, in which., by having feparated
the air, we difcover that acrimony or attra¬
ction for water, for animal, vegetable, and
for inflammable fubftances.
That the calcarious earths really lofe a
large quantity of air when they are burnt to
quick-lime, feems fufficiently proved by an
experiment of Mr. Margraaf an exceeding¬
ly accurate and judicious Chemift. He fub-
jeded eight ounces* of ofteocolla to diftilia-
tion in an earthen retort, finifhing his procefs
with the moft violent fire of a reverberatory,
and caught in the receiver only two drams of
water, which by its fmell and properties
fhewed itfelf to be {lightly alkaline. He does
not tell us the weight of the ojlevcolla re¬
maining in the retort, *and only fays, that it
was converted into quick-lime 5 but as no cal-
carious earth can be converted into quick-lime,''
or bear the heat which he applied without
lofing above a third of its weight, we may
C- fafely'
f Mem. de l’Acad, de Berlin, an, 1748, p. 57,
x88 ESSAYS and OBSERVATIONS
fafely conclude, that the lofs in his experi¬
ment was proportional, and proceeded chiefly
from the diffipation of fixed air.
According to our theory, the relation of
the calcarious earth to air and water appeared
to agree with the relation of the fame earth
to the vitriolic and vegetable acids. As
chalk for inflance has a ftronger attraction
for the vitriolic than for the vegetable acid,
and is diffolved with more difficulty when
combined with the firft, than when joined to
the fecond : fo it alfo attracts air more
ftrongly than water, and is diffolved with
more difficulty when faturated with air than
when compounded with water only.
A calcarious earth deprived of its air, or
in the flate of quick-lime, greedily abforbs a
confiderable quantity of water, becomes fo-
lable in that fluid, and is then faid to be
flaked $ but as foon as it meets with fixed
air, it is fuppofed to quit the water and join
itfelf to the air, for which it has a fuperior
attraction, and is therefore reftored to its
firfi: flate of mildnefs and infolubility in
water.
When flaked lime is mixed with water,
the fixed air in the water is attracted by
. - . . ■ the
PHYSICAL and LITERARY. 189
the lime, and faturates a fmall portion of it,
which then becomes again incapable of difib-
lution, but part of the remaining flaked lime
is diflolved and compofes lime-water.
If this fluid be expofed to the open air,
the particles of quick-lime which are neareft
the furface gradually attrad: the particles of
.fixed air which float in the atmofphere. But
at the fame time that a particle of lime is thus
faturated with air, it is alfo reftored to its
native ftate of mildnefs and infolubility $ and
as the whole of this change muft happen at
the furface, the whole of the lime is fuc-^
ceffively collected there under its original
form of an infipid calcarious earth, called the
cream or crufts, of lime-water.
When quick-lime, itfelf is expofed to the
open air, it abforbs the particles of water
and of fixed air which come within its
fphere of attraction, as it meets with the firft
of thefe in greateft plenty, the greateft part
of it affumes the form of flaked lime ; the
reft is reftored to its original ftate ; and if it
be expofed for a fuflicient length of time, the
whole of it is gradually faturated with air, to
which the water as gradually yields its place.
’ , - We
!9o ESSAYS AND OBSERVATIONS
< We have already fhewn by experiment,
that magnefia alba is a compound of a pecu¬
liar earth and fixed air. When this fubftance
is mixed with lime-water, the lime (hews a
Wronger attraftion for fixed air than that of
the earth of magnefia ; the air leaves this
powder to join itfelf to the lime. And as
neither the lime when faturated with air,
nor the magnefia when deprived of it, are
foluble in water, the lime-water becomes per-
fedtly pure and ihfipid, the lime which it
contained^ being mixed with the magnefia.
But if the magnefia be deprived of air by caU
cination before it is mixed with the lime-
water, this fluid fuffers no alteration.
If quick-lime be mixed with a- difiblved
alkali, it likeways fhews an attraction for
fixed air fuperior to that of the alkali.- It
robs this fait of its air,' and thereby becomes
mild itfelf, while the alkali is confequently
rendered more corrofive, or difcovers its na¬
tural degree of acrimony or flrong attraction
for water, and for bodies of the inflammable,
and of the animal and vegetable kind; which
attraction was lefs perceivable as long as it
was faturated with air. And the volatile
alkah when deprived of its air, befides this
attradion
PHYSICAL and LITERARY. 19!
attradlion for various bodies, difcovers like-
ways its natural degree of volatility, which
was formerly fomewhat repreffed by the air
adhering to it, in the fame manner as it is re¬
preffed by the addition of an acid.
This account of lime and alkalis recom¬
mended itfelf by its fimplicity, and by afford¬
ing an eafy folution of many phenomena, but
appeared upon a nearer view to be attended
with confequences that were fo very mew and
extraordinary, as to render fufpicious the
principles from which they were drawn.
I refolved however to examine, in a parti¬
cular manner, fuch of thefe confequences as
were the moil unavoidable, and found, the
greateft number of them might be reduced
to the following proportions :
I. If we only feparate a quantity of air
from lime and alkalis, when we render them
cauftic they will be found to lofe part of their
weight in the operation, but will faturate the
fame quantity of acid as before, and the fa-
turation will be performed without effer-
vefcence.
II. If
ip 2 ESSAYS and OBSERVATIONS
II. If quick-lime be no other than a cal¬
caneus earth deprived of its air, and whofe
attraction for fixed air is ftronger than that of
alkalis, it follows, that, by adding to it a fuf-
ficient quantity of alkali Saturated with air, the
lime will recover the whole of its air, and be
entirely reftored to its original weight and con¬
dition : and it alfo follows, that the earth fe-
parated from lime-water by an alkali, is the
lime which was difiolved in the water now
reftored to its original mild and infoluble
ftate.
III. If it be fuppofed that flaked lime does
not contain any parts which are more firey,
aCtive or fubtile than others, and by which
chiefly it communicates its virtues to water ^
but that it is an uniform compound of lime
and water : it follows, that, as part of it can
be difiolved in water, the whole of it is alfo
capable of being difiolved.
IV. If the acrimony of the cauftic alkali
does not depend on any part of the lime ad¬
hering to it, a cauftic or foap-ley will confer
quently be found to contain no lime, unlefs
the quantity of lime employed in making it
were greater than what is juft fuffiaent to
extraCt the whole air of the alkali 5 for then
PHYSICAL and LITERARY. 193
as much of the fuperfluous quick-lime might
poffibly be diffolved by the ley as would be
' diffolved by pure water, or the ley would
contain as much lime as lime-water does.
V. We have fhewn in the former experi¬
ments, that abforbent earths lofe their air
when they are joined to an acid ; but recover
it, if feparated again from that acid, by means
of an ordinary alkali : the air paffing from
the alkali to the earth, at the fame time that
the acid paffes from the earth to the alkali.
If the cauftic alkali therefore be deftitute
of air, it will feparate magnefia from an acid
under the form of a magnefia free of air,
or which will not effervefce with acids ; and
the fame cauftic alkali will alfo feparate a cal-
carious earth from acids under the form of
a calcarious earth deftitute of air, but fatu-
rated with water, or under the form of flaked
lime.
These were all neceffary conclufions from
the above luppofitions. Many of them
appeared too improbable to deferve any fur¬
ther attention : fome however, I found upon
reflection, were already feconded by expe¬
rience. Thus Hoffman has obierved, that
quicklime does not effervefce with fpirit of
Vol. II. B b vitriol.
194 ESSAYS and OBSERVATION'S
ft
vitriol^ ; and it is well known that the cauftic
fpirit of urine, or of fait ammoniac, does not
emit air, when mixed with acids. This con-
fideration excited my curiofity, and determin¬
ed me to inquire into the truth of them all
by way of experiment. I therefore engaged
myfelf in a fet of trials ; the hiftory of which
is here fubjoined. Some new fafe are like-
ways occafionally mentioned ; and here it
will be proper to inform the reader, that X
have never mentioned any without fatisfying-
myfelf of their truth by experiment, tho’ X
have fometimes taken the liberty to negledf
defcribing the experiments when they feemed
fufficiently obvious.
Desiring to know how much of an acid
a calcarious earth will abforb, and what
quantity of air is expelled during the diffolu-
tion, X faturated two drams of chalk with
diluted fpirit of fait, and ufed the Florentine
ftafk, as related in a fimilar experiment upon
magnefia. Seven drams and one grain of
the acid ftnifhed the diffolution, and the chalk
loft two fcruptes and eight grains of air.
This experiment was neceffary before the
following, by which X propofed to inquire
into
* Hoff. Op. T. iv. p. 480-
PH Y S I C A L and L I T E RARY. 19 5
into the truth of the firft proportion fo far
as it relates to quick-lime.
Two drams of chalk were converted into
a perfect quick-lime, and loft two fcruples
and twelve grains in the fire. This quick¬
lime was flaked or reduced to a milky liquor
with an ounce of water, and then diffolved
in the fame manner, and with the lame acid,
as the two drams of chalk in the preceding
experiment. Six drams, two fcruples and
fourteen grains of the acid finifhed the fa til-
ration without any fenfible effervefcence or
lofs of weight.
It therefore appears from thefe experi¬
ments, that no air is feparated from quick¬
lime by an acid, and that chalk faturates
nearly the fame quantity of acid after it is
converted into quick-lime as before.
With re (pc ft to the fee on d propofition, I
tried the following experiments,
A piece of perfect quick-lime made from
two drams of chalk, and which weighed one
dram and eight grains, was reduced to a very
fine powder, and thrown into a filtrated mix¬
ture of an ounce of a fixed alkaline fait and
two ounces of water. After a flight di-
geftion, the powder being well wafhed and
1 96 ESSAYS and OBSERVATIONS
dried, weighed one dram and fifty eight
grains. It was fimilar in every trial to a fine
powder of ordinary chalk, and was therefore
faturated with air which muft have been fur-
nifhed by the alkali.
A dram of pure fait of tartar was diffolved
in fourteen pounds of lime-water, and the
powder thereby precipitated, being carefully
collected and dried, weighed one and fifty
grains. When expofed to a violent fire, it
was converted into a true quick-lime, and
had every other quality of a calcarious earth.
This experiment was repeated with the
volatile alkali, and alfo with the foflil or al¬
kali of fea-falt, and exadlly with the fame
event.
The third propofition had lefs appearance
of probability than the foregoing ; but, as
an accurate experiment was the only teft of
its truth, I reduced eight grains of perfect
quick-lime made of chalk, to an exceedingly
! fubtile powder, by flaking it in two drams of
diftilled water boiling hot, and immediately
threw the mixture into eighteen ounces of
diftilled water in a fiafk. After fhaking it,
a light fediment, which floated thro’ the li¬
quor, was allowed to fubfide 5 and this, when
collected
PHYSICAL and LITERARY. 197
collected with the greateft care, and dryed,
weighed, as nearly as I could guefs, one third
of a grain. The water tailed ftrongly of the
lime, had all the qualities of lime-water, and
yielded twelve grains of precipitate, upon the
addition of fait of tartar. In repeating this
experiment, the quantity of fediment was
fometimes lefs than the above, and fometimes
amounted to half a grain. It confifted part¬
ly of an earth which effervefced violently
with aqua fortis , and partly of an ochry pow¬
der, which would not diffolve in that acid.
The ochry powder, as it ufuaily appears in
chalk to the eye, in the form of veins running
thro' its fubftance, muft be confidered only
as an accidental or foreign admixture ; and,
with refpedl to the minute portion of alkaline
earth which compofed the remainder of the
fediment, it cannot be fuppofed to have been
originally different from the reft, and incapa¬
ble, from its nature, of being converted into
quick-lime, or of being diffolved in water •>
it feems rather to have con lifted of a irnall
part of the chalk in its mild ftate, or fatu-
rated with air, which had either remained, for
want of a fufficient fire to drive it out entirely,
or had been furnifhed by the diftilled water.
I
- sr98 ESSAYS and OBSERVATIONS
I indeed expected to fee a much larger quan¬
tity of fediment produced from the lime, on
account of the air which water conftantly con¬
tains, and with a view to know whether wa¬
ter retains its air when fully faturated with
lime, a lime-water was made as ftrong as pof-
fible 5 four ounces of which were placed un¬
der the receiver of an air-pump, together with
four ounces of common water in a vial of the
fame fize ; and, upon exhaufting the recei¬
ver, without heating the vials, the air arofe
from each in nearly the fame quantity : from
whence it is evident, that the air, which
quick-lime attradls, is of a different kind from
that which is mixed with water. And that
it is alfo different from common elaftic air, is
fufficiently proved by daily experience ; for
lime-water, which foon attracts air, and forms
a cruft when expofed in open and fhallow vef-
fels, may be preferved, for any time, in bot¬
tles which are but flightly corked, or clofed
in fuch a manner as would allow free accefs
to elaftic air, were a vacuum formed in the
bottle. Quick-lime therefore does not attract
air when in its molt ordinary form, but is ca¬
pable of being joined to one particular fpecies
only, which is difperfed thro’ the atmofphere,
either ■
PHYSICAL and LITERARY. j99
either in the fhape of an exceedingly fubtile
powder, or more probably in that of an ela-
ftic fluid. To this I have given the name of
fixed air, and perhaps very improperly • but
I thought it better to ufe a word already fa¬
miliar in philofophy, than to invent a new
name, before we be more fully acquainted
with the nature and properties of this fub-
fiance, which will probably be the fubied of
my further inquiry.
It is, perhaps, needlefs to mention here,
that the calcarious fubftances ufed in making
the above experiments fhould be of the pureft
kind, and burnt with the utmoil violence of
heat, if we would be fure of converting them
into perfed quick-lime. I therefore made ufe
of chalk burnt in a fmall covered crucible with
the fiercefl fire of a Biack-fmith’s forge, for
half an hour, and found it neceflary to employ,
for this purpofe, a crucible of the Aufirian
kind, which refemble black lead \ for if any
calcarious fubflance be heated to fuch a degree
in an ordinary or He/Jia?i crucible, the whole
of it is melted down, together with part of the
veffel, into glafs.
I now prepared to inquire into the pro¬
perties of the cauftic alkali ; in order to which,
I
200 ESSAYS AND OBSERVATIONS
I made a cauftic or foap ley in the following
manner.
Twenty fix ounces of very ftrong quick¬
lime made of chalk, were flaked or reduced
to a fort of fluid pafte, with eleven pounds
of boiling water, and then mixed in a glafs
veflel with eighteen ounces of a pure fixed
alkaline fait, which had been firft diflolved
in two pounds and a half of water. This
mixture was fhaken frequently for two hours,
when the aftion of the lime upon the alkali
was fuppofed to be over, and nothing remain¬
ed but to feparate them again from one ano¬
ther. I therefore added 1 2 pounds of water,
ftirred up the lime, and, after allowing it to *
fettle again, poured off as much of the clear
ley as poffible.
The lime and alkali were mixed together
under the form of a very thick milky liquor
or fluid pafte ; becaufe they are thus kept in
perpetual contact and equal mixture until
they have adted fufficiently upon one another:
whereas in the common way of ufing a larger
quantity of water, the lime lies for the molt
part at bottom, and, tho’ ftirred up ever fo
often, cannot exert its influence fo fully upon
the
PHYSICAL and LITERARY.
204
the alkali, which is uniformly diffufed thro’
every part of the liquor.
The above ley was found upon trial to be
faturated by acids without the leaft effervef-
cence or diminution of weight.
It was now proper to examine whether
the alkali fullered any lofs in becoming
cauftic, which I propofed to attempt by as¬
certaining the ftrength of the ley, or the
quantity of fait which a given portion of it
contained ; from which by computation
fome imperfed knowledge might be obtained
of the quantity of cauftic produced from the
eighteen ounces of mild fait.
I therefore evaporated fome of my ley,
but foon perceived that no certain judgment
could be formed of its ftrength in this way,
becaufe it always abforbed a confiderable
quantity of air during the evaporation, and
the dried fait made a pretty brifk effervef-
cence with acids, fo that the ley appeared
ftronger than it really was ; and yet, upon
proceeding in the eftimate from this rude
and unfair trial, it appeared that the fait had
loft above a fixth in becoming cauftic, and
the quantity of acid faturated by two drams of
Vol. II. C c it
■toi ESSAYS and OBSERVATIONS
it was to the quantity of acid faturated by two;
drams of fait of tartar, nearly as fix to five.
These experiments are therefore agreeable
to that part of the fecond propofition which
relates to the cauftic alkali.
Upon farther examining what changes the
alkali had Undergone, I found that the ley
gave only an exceeding faint milky hue to
lime-water ; becaufe the cauftic alkali wants
that air by which fait of tartar precipitates
the lime. When a- few ounces of it were
expofed in an open (hallow vefiel for four
and twenty hours, it imbibed a fmall quan¬
tity of air, and made a flight effervefcence
with acids. After a fortnight’s expofure in
the fame manner, it became entirely mild,
effervefced as violently with acids, and had
the fame effedt upon lime-water as a folution
of an ordinary alkali. It likeways agrees
with lime-water in this refpedt, that it may
be kept in clofe veflels, or even in bottles
which are but flightly covered, for a confide-
rable time, without abforbing a fenfible quan¬
tity of air.
In order to know how much lime it con¬
tained, I evaporated ten ounces in a fmall
filter
PHYSICAL and LITERARY. 203
Civet* difli over a lamp, and melted the fait,
after having diffipated the water"*.
The cauftic thus produced was diffolved
again in a fmall quantity of water, and de-
poiited a trifling portion of fediment, which
I imagined at firft to be lime ; but finding
that it could eafily be diffolved in a little
more water, concluded it to be a vitriolated
tartar, which always accompanies the fixed
alkali of vegetables.
I then faturated the folution of the cauftic
fait with fpirit of vitriol, expe&ing thus to
detedt the lime ; becaufe that acid precipi¬
tates a calcarious earth from its ordinary folia¬
tions. During the faturation, a large quan¬
tity of white powder was formed ; but this
bikeways turned out to be a vitriolated tartar,
which had appeared in the form of a
powder, becaufe there was not enough of
water in the mixture to diffolve it.
Lastly
* This evaporation was performed in a filver difli, on ac¬
count of the acrimony of the fait ; which is fo very great,
that, having once evaporated a part of the fame ley in a
bowl of Englifh earthen or hone ware, and melted the cauftic
with a gentle heat, it corroded and diffolved a part of the
bowl, and left the infide of it pitted with fmall holes.
io4 ESSAYS and OBSERVATIONS
Lastly, I expofed a few ounces of the
ley in an open (hallow veffel fo long, that
the alkali loft the whole of its caufticity,
and feemed entirely reftored to the (late of
&n ordinary fixed alkali ; but it did not
however depofite a (ingle atom of lime. And
to affure myfelf that my cauftic ley was not
of a Angular kind, I repeated the fame ex¬
periments with an ordinary foap-ley, and
with one made by mixing one part of a pure
fixed alkaline fait with three parts of common
ftone lime frefh flaked and fifted 5 nor could
I difeover any lime in either. The firft of
thefe contained a fmall quantity of brimftone,
and was far from being perfectly cauftic, for
it made a pretty bri(k effervefcence with
acids 5 but the laft was fo entirely deprived
of its air, that it did not diminifh in the lead
the tranfparency of lime-water.
Th£se experiments feem therefore to fup^
port the fourth propofition, and to £hew
that the cauftic alkali does not contain any
lime.
As it feems probable, from the quicknefs
and eafe wherewith the alkali was rendered
cauftic, that more lime bad been employed than
what was juft diffident to extra# the whole
PHYSICAL and LITERARY.
205
of its air, we are furprifed to find that little
or none of the fuperfluous quick-lime was
diffolved by the water. But this phenomenon
will become lefs furprizing, by comparing it
with fome fimilar inftances in chemiftry.
W ater may be made to depofite a fait, by
the admixture of a fubftance which it attracts
more ftrongly than it does that fait 3 fuch
as fpirit of wine 3 and quick-lime itfelf may
be feparated from water upon the fame prin¬
ciple 3 for if that fpirit is added to an equal
quantity of lime-water, the mixture becomes
turbid and depofites a fediment, which, when
feparated and diffolved again in diftilled wa¬
ter, compofes lime-water. We may there¬
fore refer the above phenomenons with refpedl
to the ley, to the fame caufe with thefe, and
fay, that the water did not diffolve the lime,
becaufe it already contained a cauftic alkali,
for which it has a fuperior attraction.
I alfo rendered the volatile alkali cauftic,
in order to examine what change it fuffered
in the operation, and obtained an exceedingly
volatile and acrid fpirit, which neither effer-
velced with acids, nor altered in the leaft the
tfanfparency of lime-water 3 and, altho’ ve-
■ *7
Zo6 El- S SAYS and OBSERVATIONS
ry ftrong, was lighter than water, and float¬
ed upon it like fpirit of wine.
I next inquired into the truth of the fifth
propofition, in the following manner.
Two drams of epfom-falt were diiTolved in
a fmall quantity of water, and thrown into
two ounces of the cauftic-ley $ the mixture in-
ftantly became thick, like a decodtion of
ftarch or barley, by the magnefia, which
was precipitated. I then added fpirit of vi¬
triol by degrees, until the mixture became
perfectly clear, or the whole of the magnefia
was again diflblved 3 which happened with¬
out any effervefcence or emiflion of air.
EIalf an ounce of chalk was diflblved in
fpirit of fait, the quantity of which was fo
adjufted, that the mixture was not acid in
the leaft degree 5 and thefolution was thrown
into twelve ounces of the cauftic ley ; which
quantity I found, by experiment, to be fuffi-
cient for precipitating almoft the whole of the
chalk. I now filtrated this turbid liquor, and
laid the powder remaining in the paper upon
a chalk- {tone, in order to draw as much of
the water from it as pofiible, and thereby re¬
duce it to the form of a more denfe and hea¬
vy powder, that it might fubfide the more
perfectly
PHYSICAL and LITERARY. 207
perfectly in the following part of the experi¬
ment. I then mixed it with about twenty
ounces of pure water in a flafk, and, after al¬
lowing the powder to fubfide, poured off the
water, which had all the qualities of lime-
water. And I fucceffively converted eight
waters more into lime-water, feven of thefe
in the fame quantity, and with the fame ma¬
nagement, as the firft. The eighth was like-
ways in the fame quantity ; but I allowed it
to remain with the chalk, and fhook it fre¬
quently, for two days. This, after being fil¬
trated, formed a cream or cruft upon its fur—
face when expofed to the air ; changed the
colour of the juice of violets into green ; fe-
parated an orange-coloured powder from a fo-
lution of corroiive fublimate 5 became turbid
upon the addition of an alkali *, was entirely
fweetened by magnefia 5 and appeared fo
ftrong to the tafte, that I could not have dif-
tinguifhed it from ordinary lime-water. And
when I threw fome fait ammoniac into the
lime which remained, the vapour of the vo¬
latile alkali immediately arofe from the mix¬
ture.
In this experiment therefore the air is firft
*
driven out of the chalk by an acid, and then,
in
20 8 ESSAYS AND OBSERVATIONS
in order to feparate this acid from it, we
add an alkali which has been previoufly de¬
prived of its air j by which means, the chalk
kfelf is alfo obtained free of air, and in an a-
crid form, or in the form of flaked lime.
We have alfo feveral procefles for obtain¬
ing the volatile alkali in a cauftic form, which
feem to be only fo many methods of obtain¬
ing it in its pure ftate, and free of fixed air.
The firft of thefe is the feparation of the al¬
kali from an acid, merely by heat 5 an in-
fiance of which we have from Mr. Mar-
graaf*. He prepared from urine an ammo-
niacal fait, the acid of which is the bafis of
the phofphorus, and is of fuch a peculiar na¬
ture, that it endures a red heat without being
diffipated. Sixteen ounces of the neutral fait
were fubjedted by him to diftillation. The
acid remained in the retort, and he found in
the receiver eight ounces of an alkaline fpirit,
which, he tells us, was extremely volatile,
very much refembling the fpirit of fait am¬
moniac diftilled with quick-lime -} and no
cryftals were formed in it, when expofed to
the cold air.
A
* Mem. del’ Acad, de Berlin, an. 1746, p. S;a
PHYSICAL ai*d LITERARY. 209
A cauftic volatile alkali may alfo be obtain¬
ed, by mixing fait ammoniac with half its
Xveight of a cauftic fixed alkali, or of magne-
fia which has been previoufly deprived of its
air by fire ; and then fubmitting thefe mix¬
tures to diftillation : Or merely by adding a-
ny ordinary volatile alkali to a proper quanti¬
ty of a cauftic ley 3 for in this cafe the air
pafles from the volatile to the fixed alkali, by
a fuperior attraction for the laft, and, by a
gentle heat, the compound yields a (pint fi-
milar to that prepared from fait ammoniac
and quick-lime.
It is therefore probable, that, had we al¬
fo a method of feparating the fixed alkali
from an acid, without, at the fame time, fa-
turating it with air, we fhould then obtain it
in a cauftic form ; but I am not acquainted
with an inftance of this feparation in chemi-
ftry. There are two indeed which, at firffc
fight, appear to be of this kind 5 thefe are
the feparation of the fixed alkali from the ni¬
trous acid by means of inflamed charcoal,
in the procefs for making nitrurn fixation , and
of the fame alkali, from vegetable acids mere¬
ly by heat ; but, upon examining the pro¬
duct of each procefs, we find the alkali either
Vol.IL Dd fully
3io ESSAYS AND OBSERVATIONS’
fully or nearly faturated with air. In the firfty
either the charcoal or the acid, or both to¬
gether, are almoffc wholly converted into air 5
a part of which is probably joined to the al¬
kali. In the fecond, the acid is not properly
feparated, but rather deftroyed by the fire : a
confiderable portion of it is converted into an
inflammable fubftance6; and we learn from
Dr. Hales , that the bodies of this clafs contain
a large quantity of fixed air.
When we confider that the attraction of
alkalis for fixed, air is weaker than that of
the calcarious earths, and reflect upon the ef¬
fects of heat in chemiftry, we are led to ima¬
gine, that alkalis might be entirely deprived
of their air, or rendered perfectly cauftic, by a
fire fomewhat weaker than that which is fuf-
ficient to produce the fame change upon lime ;
but this opinion does not feem agreeable to
experience.
The alkalis do, however, acquire fome
degree of caufticity in a ftrong fire, as ap¬
pears from their being more eafily united with
fpirit of wine after having been kept in fu-
fion for fome time. For that fluid, which
cannot be tinCtured by a mild fait of tartar,
will
PHYSICAL and LITERARY. 211
will foon take a very deep colour from a few
drops of a ftrong cauftic ley. The circum-
fiances which hinder us from rendering thefe
falts' perfectly cauftic by heat, are their pro¬
pensity to diffipation in the utmoffc violence
of the fire, their extreme acrimony, and the
imperfection of our common veffels. For
before the heat becomes very intenfe, the al¬
kalis either evaporate, or diffolve a part of the
crucibles in which they are contained, and
often efcape thro’ their pores ; which hap¬
pens, efpecially as foon as they have already
acquired fome degree of additional acrimony,
by the lofs of part of their air.
The fufion alfo, which they fo readily un¬
dergo, is well known by Chemifts, as a ftrong
obftacle to the reparation of the volatile from the
fixed parts of a compound by fire 5 according¬
ly, in feveral proceffes, we are directed to add
to the fufible compound fome porous fubftance
which is incapable of fufion, and will retain
the whole in a Spongy form, thereby to facili¬
tate the diffipation of the volatile parts.
In order to know whether an alkali would
lofe a part of its air, and acquire a degree of
caufticity, when expofed, with this precauti¬
on, to the aftion of a ftrong fire, I mixed an
ounce
212 ESSAYS AND OBSERVATIONS
ounce and a half of fait of tartar with three
ounces of black-lead, a fubftance of any the
moft unchangeable by chemical operations.
This mixture I expofed, for feveral hours,
in a covered crucible, to a fire fomewhat
ftronger than what is necefiary to keep fait of
tartar in fufiom When allowed to cool, I
found it ftill in the form of a loofe powder $
and taking out one half* I diluted it with wa¬
ter, and by filtration obtained a ley, which,
when poured into a folution of white marble
in aqua forth , precipitated the marble under
the form of a weak quick-lime ; for the tur¬
bid mixture gave a green colour to the juice
of violets, and threw up a cruft like that of
lime-water and the precipitated powder col¬
lected and mixed with fait ammoniac imme¬
diately yielded the fcent of the volatile alkali.
Lest it fliould here be fufpedted, that the
alkaline qualities of this mixture, and of the
precipitated marble, were not owing to a lime
into which the marble was converted, but to
the alkali itfelf which was added, it is pro¬
per to obferve, that I mixed fo fmall a propor¬
tion of the ley with the folution of marble as
made me fure, from certain experiments, that
the whole of the alkali was fpent in perform-
PHYSICAL and LITERARY. 213
mg the precipitation, and was confequently
converted into a neutral fait by attracting the
acid. The properties therefore of the mix¬
ture can only be referred to a lime, as is in¬
deed fufficiently evident from the cruft which
is peculiar to lime-water.
I was therefore allured by this experiment,
that an alkali does really lofe a part of its air,
and acquire a degree of caufticity, by the pro¬
per application of heat ; but finding by
feveral trials, that the degree of caufticity
whicbJ it had thus acquired was but weak,
and that the quick-lime produced in this ex¬
periment was exhaufted and rendered mild
by a fmall quantity of water, I expofed the
crucible together with that half of the al¬
kali which remained in it to a ftronger fire,
in order to expel a larger quantity of air, and
render it more remarkably cauftic ; but the
whole of it was diflipated by the force of the
heat, and the black lead, which ftill retained
the form of a loofe and fubtile powder,
yielded little or nothing to water.
We learn then from the above experiment
the reafon why the alkali newly obtained
from the allies of vegetables is generally of
|hc more acrid kinds of that fait. It never
appears
214 ESSAYS AND OBSERVATIONS
appears until the fubjed: be converted into
allies, and is fuppofed to be formed by the
fire, and to be the refult of a particular com¬
bination of fome of the principles of the ve¬
getable ; one of which principles is air, which
is contained in large quantity in all vege¬
table matters whatever. But as foon as the
fmalleft part of a vegetable is converted into
allies, and an alkali is thus formed, this fait
necelfarily fuffers a calcination, during which
it is kept in a fpongy form by the allies, and
fiiews a very confiderable degree of acrimony
if immediately applied to the body of an
animal $ but if the allies are for any time
expofed to the air, or if we feparate the alkali
from them by the addition of a large quantity
pf water and fubfequent evaporation, thp
fait imbibes fixed air from the atmofphere,
and becomes nearly faturated with it : the/
even in this condition it is generally more
acrid than fait of tartar, when this is pre¬
pared with a gentle heat.
Borax has fometimes been referred to the
clafs of alkalis, on account of iome referq-
blance it bears to thole falts : but it has been
demonlirated by accurate experiments, that
we Ihould rather confider it as a neutral fait ;
that
PHYSICAL and LITERARY, 215
that it is compofed of an alkali and of a par¬
ticular faline fubftance called the fedative
fait, which adheres to the alkali in the fame
manner as an acid, but can be feparated by
the addition of any acid whatever, the added
acid joining itfelf to the alkali in the place
of the fedative fait. As this conjunction of
an acid with the alkali of borax happens
without the leaft effervefcence, our principles
lay us under a neceffity of allowing that alkali
to be perfectly free of air, which muft proceed
from its being incapable of union with fixed
air and with the fedative fait at the fame time :
whence it follows, that, were we to mix the
fedative fait with an alkali faturated with air,
the air would immediately be expelled, or the
two falts in joining would produce an effer¬
vefcence. This I found to be really the cafe
upon making the trial, by mixing a final!
quantity of the fedative fait with an equal
quantity of each of the three alkalis, rubbing
the mixtures well in a mortar, and adding a
little water. It is however proper in this
place to obferve, that, if the experiments be
made in a different manner, they are attend¬
ed with a fingular circumflance. If a fmall
quantity of the fedative fait be thrown into a
ai 6 ESSAYS and OBSERVATIONS
large proportion of a diffolved fixed alkali^
the fedative fait gradually difappears, and is
united to the alkali without any efferves¬
cence ; but if the addition be repeated
feveral times, it will at laft be accompanied
with a brifk effervefcence, which will be¬
come more and more remarkable, until the
alkali be entirely faturated with the fedative
fait.
This phenomenon may be explained by
confidering the fixed alkalis as not perfeftly
faturated with air : and the fuppofition will
appear very reafonable, when we recoiled;*
that thofe falts are never produced without
a confiaerable degree of heat, which may
eafiiy be imagined to difiipate a fmall portion
of fo volatile a body as air. Now, if a fmall
quantity of the fedative fait be thrown into
an alkaline liquor, as it is very flowly dif¬
folved by water, its particles are very gra^
dually mixed with the atoms of the alkali*
They are moft ftrongly attraded by fuch of
thefe atoms as are deftitute of air, and
therefore join with them without producing
an effervefcence 3 or, if they expel a fmall
quantity of air from fome of the fait, this air
is at the fame time abforbed by fuch of the
contiguous
PHYSICAL and LITERARY. 217
contiguous particles as are deftitute of it, and
no effervefcence appears until that part of the
alkali, which was in a cauftic form or defti-
tute of air, be nearly faturated with the
fedative fait. But if, on the other hand, a
large proportion of the fedative fait be per¬
fectly and fuddenly mixed with the alkali,
the whole, or a large part, of the air is as
fuddenly expelled.
In the fame manner may we alfo ex¬
plain a fimilar phenomenons which often
prefents itfelf in faturating an alkali with
the different acids : the effervefcence is
. , ■ . v? rK " t > f,
lefs confiderable in the firft additions of
^ .. t ' * fv f* ) • ' f \ ■ ", J •i'f >
acid, and becomes more violent as the
mixture approaches the point of faturation.
This appears moft evidently in making the
jal diureticus or regenerated tartar : The
particles of thewegetable acid here employed
w KJ M. a - - -
being always diffufed thro’ a large quantity
of water, are more gradually applied to thofe
of the alkali, and during the firft additions
are chiefly united to thofe that are freeft of
air
Vol.IL Ee That
* Boerh, Operat. Chem. procefs. LX XVI.
21$ ESSAYS AND OBSERVATIONS'
That the fixed alkali, in its ordinary Rate,
is feldom entirely faturated with air, feems to
be confirmed by the following experiment.
I expofed a (mall quantity of a pure vege¬
table fixed alkali to the air, in a broad and
fhallow veffel, for the fpace of two months ;
after which I found a number of folid
cryftais, which refembled a neutral fait fo
much as to retain their form pretty well in
the air, and to produce a confiderable degree
of cold when diffolved in water. Their tafte
was much milder than that of ordinary fait
of tartar ; and yet they feemed to be com-’
pofed only of the alkali, and of a larger
quantity of air than is ufually contained in
that fait, and which had been attracted from
the atmosphere: for they Rill joined very
readily with any acid, but with a more vio-
lent effervefcence than ordinary ; and they
could not be mixed with the fmalleft portion
of vinegar, or of the fedative fait, without e-
mitting a fenfible quantity of air.
As it now appeared that feveral alkaline
fubftances have an attraftion for fixed air, I
tried a few experiments to learn the relative
ftrength of their feveral attractions.
Twenty
PHYSICAL and LITERARY. 219
Twenty four grains of magnefia in fine
powder were mixed with five ounces of the
cauftic ley in a final! vial, which was imme¬
diately corked and fhaken frequently for four
hours. The ley was then poured off, and
the magnefia w allied with repeated affufions
of water, and dried. It had loft about the
half of its weight, and when reduced to a
fine powder was readily diffolved by acids
with an effervefcence which was hardly per¬
ceivable : the alkali had therefore extracted
its air. I alfo threw7 fome frefh magnefia
into the ley which had been poured off, and
thereby rendered it perfectly mild and fimilar
to a folution of fait of tartar ; fo that it of¬
fer vefeed brifkly with acids.
With an ounce of the mild fpirit of fait
ammoniac, I mixed a dram of magnefia in
very fine powder which had been previoufly
deprived of its air by fire ; and observing that
the magnefia had a tendency to concrete into
a folid mafs, I (hook the vial very frequently.
After fome days the powder was increafed
to more than double its former bulk ; and
when the vial was opened, the alkaline fpirit
emitted a moil intolerably pungent fmelh
It likewife floated upon water, but was not
perfectly
220 ESSAYS AND OBSERVATIONS
perfe&ly cauftic ; for it Bill yielded fome air
when mixed with acids, and alfo rendered
lime-water turbid : neither of which would
probably have happened if I had ufed a
greater quantity of magnefia, or had allowed
the mixture to remain a longer time in the
vial. I now wafhed out the whole of the
mixture into a bowl, and dryed the magnefia
until it loft all fmell of the alkali. It
weighed a dram and fifty eight grains, effer¬
vesced violently with acids, and therefore
contained a large quantity of air, which had
been drawn from the alkali by a ftronger
attraction.
Having formerly fihewn, that magnefia
faturated with air feparates an acid from a cal-
carious earth, which it is not able to do after
being deprived of its air by fire ; I now
fufpe&ed that the air was the caufe of this
ieparation, becaufe I found that it was ioined
to the calcarious earth at the fame time that
the acid was joined to the earth of magnefia ;
and imagined that a pure calcarious earth
might pofiibly have a ftronger attraction for
acids than a pure earth of mgnefia.
I therefore diffolved two drams of magne¬
fia in the marine acid, and thus obtained a
compound
PHYSICAL and LITERARY. 221
compound of an acid and of the pure earth
of this fubftance ; for the air which was at
firft attached to it, was expelled during the
diflolution. I then added thirty grains of
ftrong quick-lime in exceeding fine powder,
Ihook the mixture well, and filtrated it. The
powder remaining in the paper, after being
well walhed, was found to be a magnefia,
which, as I expected, was deftitute of air ;
for it was diflolvcd by the vitriolic acid with¬
out effervefcence. And the filtrated liquor
contained the lime united to the acid ; for
upon dropping fpirit of vitriol into it, a white
powder was immediately formed.
We muft therefore acknowledge a ftronger
attraction between the calcarious earths and
acids than between thefe and magnefia : but
how does it then happen, that, if magnefia
faturrtted with air be mixed with a compound
of acid and calcarious earth, thefe two laft,
which attraCt one another the molt firongly,
do not remain united ; but the acid is joined
to the magnefia, and the calcarious earth to
the air which it attracts much more weakly
than it does the acid ? Is it becauie the fum
of the forces which tend to join the magnefia
to the acid and the calcarious earth to the
♦ . ;
air
222 ESSAYS and OBSERVATIONS
air, is greater than the fum of the forces
which tend to join the calcarious earth to
the acid, and the magnefia to the air : and
becaufe there is a repulfion between the acid
and air, and between the two earths ; or they
are fomehow kept afunder in fuch a manner
as hinders any three of them from being-
united together ?
The firft part of this fuppofition is favour¬
ed by our experiments, which feem to ffiew
a greater difference between the forces
wherewith the calcarious earth and magnefia
attradt fixed? air, than between thofe which
difpofe them to unite with the acid. The
repulfions however hinted in the fecond are
perhaps more doubtful, tho? they are fug-
gefted in many other inflances of decom-
pofition ; but the bounds of my prefent pur¬
pose will not allow me to enter upon this
fubjedt, which is one of the moil exteniive
in chemiftry.
We meet alfo with a difficulty with re-
fpedt to the volatile alkali fimilar to the
above. Thus a calcarious earth that is pure
or tree of air has a much ftronger attraction
for acids than a pure volatile alkali, as is evi¬
dent when we mix quick-lime with fait-
ammoniac 5
PHYSICAL and LITERARY. 223
_ ’ /
for the alkali is then immediately detached
from the acid : and agreeably to this I found,
upon trial, that a pure or cauftic volatile
alkali does not feparate a calcarious earth
from an acid. Yet, if we mix a mild volatile'
alkali, which is a compound of alkali and*
air, with a compound of acid and calcarious
earth, thefe two lad, which attract one an¬
other moil ftrongly, do not remain united ;
but the acid is joined to the alkali and the
earth to the air, as happens in the precipi¬
tation of a calcarious .earth from an acid,
by means of the common; or mild volatile
alkali. Ts
- I remember likewife a parallel in dance
with regard to quick-filver. This metal has
an attraction for the vitriolic acid, and when
joined to it appears under the form of turbith
mineral : but this attraction is weaker than
*
that of the fixed alkali for the fame acid ;
for if we mix a diffolved fait of tartar with
turbith mineral, the turbith is converted into
a brown powder, and the alkali into vitrio-
lated tartar 5 which change happens the
fooner, if the pure or cauftic alkali is ufed.
Yet, if to a compound of quick-filver and the
nitrous acid, we add a compound of the fixed
alkali
£24 ESSAYS AND OBSERVATIONS
alkali and the vitriolic acid, or a vitriolated
tartar, and digeft the mixture with a ftrong
heat, the vitriolic acid does not remain with
the alkali, but is joined to the quick-filver
which it attradts more weakly, compofing
with it a turbith mineral 5 while the al¬
kali is joined to the nitrous acid which it
likeways attracts more weakly than it
does the vitriolic, and is converted into falt-
petre.
From fome of the above experiments,
it appears, that a few alterations may be
made in the column of acids in Mr. Geoffrey §
table of elective attractions, and that a new
column may be added to that table, ac¬
cording to the following fcheme, where
the alkaline fubftances are all confidered as
in their pure Rate and free of fixed air.
1 ' ^
Acids. Fixed air.
Fixed alkali, Calcarious earth.
Calcarious earth, Fixed alkali.
Volatile alkali and magnefia, Magnefia.
* # % % * % Volatile alkali.
* % *
At
PHYSICAL and LITERARY* 225
At the foot of the firft column feveral
of the metals might follow, and after thefe
the earth of alum ; but as I don’t know
what number of the metals fhould precede
that earth, I have left it to be determined by
further experience.
The volatile alkali and magnefia are *
placed in the fame line of this column ; be-
caufe their force of attraction, feems pretty
equal. . When we commit a mixture of
magnefia and fait ammoniac to diftillation,
the alkali arifes and leaves the acid with the
magnefia ; becaufe this e
the acid, repreffes its vola
* * • <• .
alio to diminifh thd cohefion of the acid and
*
alkali, and to render them feparable by -a
gentle heat* If the magnefia be faturated
with air, this likewife, on account of its
volatile nature and attraction for the alkali,
* * ‘ • • • • f t - ,
is driven up along with it, and makes it ap»
pear under a mild form, and in the fame
manner do the alkali and air a rife from a
mixture of fait ammoniac and of a crude.
• • • , r •
calfarious earth.
‘ ’ F f
:arth, by attracting
tilky, and it fee ms
Art.
6
22 6 ESSAYS AND OBSERVATIONS
Art. IX.
Of the Analyfis andUfes of Peat , by Alexan¬
der Lind, Efquire
' 'The Analyfis of Peat .
FIve ounces of peat, hard, dry, and of a'
deep brown colour, found fix or feven
miles from Edinburgh , being diftilled with a
gradual heat, gave firft an ounce and an half
of clear water ; after which the oil began to
come over, firft yellow, then darker colour¬
ed, till it became like tar, and along with it,
a yellow or brown coloured acid oily liquor,
ftrongly empyreumatic, to the quantity of fix
drams : this liquor, towards the iaft, became
alkaline: but of this there was only a final!
quantity ; for the diftilled liquor that came
over firft, was found to be confiderably acid,
fo that it took more than a dram of oL tart .
per deliquium to faturate it ; if the diftillation
had been continued with a very violent heat,
there would have come over more alkaline
fpmt with the pitchy oil : the quantity of
4 oil
1744-
•PHYSICAL and LITERARY. '227
oil that came over was two drams and an
half ; it coagulates in the cold, and melts
with a fmall heat. There remained in the
retort two ounces of coal ; which being care¬
fully burnt in a crucible, left eleven drams
and a few grains of fine yellow allies.
That it may appear how far the Scotch
and Dutch peats agree, I fhall next give the
malyfu of fome Dutch peat made by Degner .
He took twenty four ounces of peat, which
being firft reduced to a powder ; and then
put in a retort, yielded, by a gentle diftillath
on, a good quantity of in lipid phlegm, with
an empyreumatical fmell. This being taken
away, there followed next a yellow fpirit,
and about the neck of the retort, remained
flicking a certain white undtuous earth, re-
fembling a volatile fait. The degree of heat
being increafed, there came forth a white
fnioke, with which a red oil tiling at the
fame time, was collected in the receiver, in
the form of a thick pitchy matter, fwiming
upon the fpirit, and flicking ftrongly to the
fides of the veflfeh In the retort remained
only a black coal.
Having weighed each of thefe feparate-
ly, the coal was nine ounces fix: drams ; the
thick
228 ESSAYS AND OBSERVATIONS
thick pitchy oll? an ounce and an half ; the
volatile oily fait or fpirit four ounces ; the
reft, the infipid phlegm received in an open
receiver. :
The phlegm being firft examined,' Was
nothing but a fimple clear watery liquor,
without tafte or frnell. i
The rediih yellow liquor that came next,
was a liquid volatile undtuous fait, compofed
of a watery phlegm, a volatile fait, and a
little oil, which commonly goes under the
name of fpirit. This mixt with fpirit of fea
fait occafioned only a few bubbles ; it raifed
with oil of vitriol an effer vefcence, and turned
muddy ; it precipitated a folution of mercury
In aqua forth, into a black powder, turned
fyrop of violets green, had no effe'dt upon
chalk, fpirit of fait ammoniac : fpirit of harts¬
horn made no other change upon it, hut
turning the liquor, which was before muddy,
clear. From all which, he fays, it appears,
this fpirit is of an alkaline nature ; and that
except a little oil, contains chiefly a volatile
alkaline fait.
The oil which was found fwiming upon
the water or fpirit had a ftrong empyreuma-
ficai imeil, tho’ not fo fetid as the diftilled oil
PHYSICAL and LITERARY. 229
of animals, yet ftronger than that of oils di¬
ddled from bituminous mineral fubftances,
and was in fmell the moft like that of peat
fmoke. In the cold, it congealed into a body
of the confidence of foap or honey, or rather
into a pitchy fubftance of a redifh brown co¬
lour, being of a cauftic pungent tafte; upon
the fire it melted like wax, and when cold,
looked like the foot of peat.
This oil eafily catches fire, but is foon a-
gain extinguished. When kindled, it burns
like weak Spirit of wine, but not fo intenfely.
When put upon the fire in a fpoon, if you ap¬
proach a lighted candle, it kindles into a flame 5
and, upon the removal of the candle, is im¬
mediately extinguished ; So it mud be fre¬
quently kindled before it wholly confumes.
The cinder that remained in the retort,
being put in the fire, in a Short time turn¬
ed red, and immediately, without Smoke or
flame, fell into grey afhes, nothing different
from ordinary peat-afhes. Thefe afhes contain
lefs Salt than thofe of wood. All peat-afhes do
not yield the fame quantity of fait, but differ
according to the quality of the peat. From
a pound of Dutch afhes, Degtier, after boil-r
ing, filtrating, and infpiffating in the ordi-
, ' nary
23o ESSAYS and observations
nary way, obtained only half an ounce of a
redifh impure fait, mixt with much earth :
from other peats that leave after burning a
red afh, and that were taken from dryer
ground, he had an ounce of a redifh im¬
pure fait.
This fait, he fays, has rather a faline than
alkaline tafte ; and when expofed to the o-
pen air, runs flowly, after the manner of fuch
faline lixivious fait. Being difiolved in wa¬
ter and mixed with oil of vitriol, it becomes
turbid, with a fmall bubbling up. With fix¬
ed fait, or fpirit of harts-horn, it turns muddy;
with fpirit of fea fait, there is no change, the
liquor remaining clear, only a few bubbles.
It coagulates foap when boiled with it, in the
fame manner that fea fait does. This fait
difiolved again in water, filtrated and infpifi*
fated until it begins to cryftallize, gathers,
when fet in a cool place, into a fait of a cu¬
bical form, and when thrown into the fire,
makes a noife like fea fait that is decrepitated.
The liquor being further infpiffated and fet
to cryftallize a fecond time, yielded a nitrous
fait ; the remaining liquor was a pure lixi¬
vious alkaline fait, that made a firong eiier-
vefcence with acids. From all which it ap-
i
PHYSICAL and LITERARY, 23 1
pears, that this fait is principally compofed
of a fait like that of common fea fait, with a
fmall proportion of the alkaline kind.
What remained after the fait was extract¬
ed out of the afhes, was only a llimy earth
and fome fand.
To thefe analyfes, I fhall add two others.
Dr. Smidberg a Phyfician at the Hague, ha¬
ving diftilled fome peat in a retort, obtain¬
ed from it a fpirit, an oil, a volatile fait, all
of them much like that of hartshorn. Ott-
- * ■*- . „ 1
man an Apothecary at Stutberg , from a Swa¬
bian peat, had a volatile fpirit, like that of
fpirit of tartar, a fetid oil, but no volatile
fait.
The TJfes of Peat.
The principal ufe* of peat is burning, not
only for the (ervice of families, but likeways
for that of a great many trades ; fuch as
brewers, bakers, diftillers, making of lime,
&c. : and, as there is a good deal of diffe¬
rence in peats, and fome kinds preferred to
others, I (hall here take notice of fome of the
principal differences.
The
ip- ESSAYS AND OBSERVATIONS
The fir ft is, with refpedt to the place out
of which they are taken. Such as are got
from brackifh grounds, near the fea, alfo fuch
as are impregnated with vitriol or fulphur,
have a difagreeable fmell, and are hurtful to
the health. In Zealand , they have a kind
.. - --
of peat, which, when burning, makes eve¬
ry body in the room look like a dead perfonj
and, when they fit long by the fire, grow
faintifh : it alfo turns the bottom of their
» T -
veffels white. Peats taken from modes, free
' v r *
of all minerals, have none of the above
mentioned, or any other bad effe£t.
" As to the matter itfelf, that differs in ma»
fiy refpedts 5 fo that in the fame mofs, ac¬
cording to the different depth of it, there are
three or four different kinds of peats found.
In North Britain , in the province of Gronin¬
gen*, and in feveral other places, that which
is uppermoft, is light and fpungy ; further
down, better ; and at bottom, is a fubftance
that is black, and makes a firm folid peat.
In Holland , that which lies uppermoft is
heft, being of a dark or black colour, to
which others fucceed of different colours and
fubftances not fo good. That which is light
and fpungy, taken from a barren heathy
PHYSICAL and LITERARY. 233
.. _ .. I \ 4 - ... v • ,.1 , J J
. * v#
ground, or from a dry fandy foil ; alfo firch
mofs as is much mixed with pieces of rotten
wood, roots, mud, gravel, or fand, or which
confuming quickly, leaves behind a great
many impurities mixed with its adies, is
bad.
± k 1 > *
Peats differ confiderably, according to
the pains bellowed in making them. Such
as are perfectly freed from all hetrogeneous
matter, well knead and wrought, are the
belt of all. Upon which account, peats,
made in the province of Holland , where no
labour is fpared in the working them, are
preferable to all others $ tho’, in other places,
the fubflance may be equally good. A
Dutch peat fix inches long and three or four
thick, will weigh a pound 5 a peat made at
Nimnguen , of the lame dimenfions, will not
weigh above half a pound, often lefs. It is
a general obfervation, that all peats made of
mofs-mud, and well knead, are confiderabiy .
heavier than fuch as are only cut out of the
mofs.
Peats that are of a dark colour, and folid,
* *• * ' - • ' ... * t v i t .. . » . ! , ' : V i u
that continue longed: in the fire without con-
fuming, that have a good cinder, and fall into
white afires, are mod edeemed : on the
yoL. II. G g contrary.
234 ESSAYS and OBSERVATIONS
contrary, fuch as are light and porous, con-
fume quickly in the fire, leave no cinder,
but a great many impurities and afhes, are
little valued.
The afhes of peats differ alfo confiderably
in colour, quantity, and weight ; as to which
nothing certain can be determined. Some¬
times the white, fometimes the grey, and
at other times the red, are heaviefl. In
Ftiejland , the peat that leaves the red afhes,
Degner fays, is heavieft j about Nimiguen
thofe that are red are found lighter than the
Dutch peat which leaves a grey afh.
The Brewer, Difliller, and other trades,
prefer the peat that leaves a red afh, which,
tho’ it feldom has a firm cinder, yet burns
violently. The Baker makes choice of the
light turf, and in North -Holland^ where the
inhabitants are extremely cleanly, they ufe
the peat that has red afhes, upon account
of their being heavier than the white, and
therefore not fo apt to fly about and fpoir
their furniture.
Besides the ufes now commonly made of
peats, there are two others in which, I think,
they may be employed with great advantage.
The firft is, the fmelting iron ore, the only
• fewei
PHYSICAL and LITERARY. 235
fewel at prefent ufed in that operation is
charcoal of oak, and other hard woods ; a-
-ny attempt made to do it with pit-coal, fo far
as I can learn, has hitherto proved unfuccefs-
ful ; and indeed from the nature of that fub-
ftance, there feems little hopes of ever bring¬
ing it to anfwer the end, the bituminous or
inflamable part of pit-coal having nearly the
fame effedt upon iron, which common ful-
phur has. It deflroys, as experience (hews,
the malleability of iron and all other metals.
Pit-coal has likeways another bad quality,
which I have often found to my coft. With
a ftrong heat it runs into a glafly fubftance,
which in time, by its (licking fo clofely to¬
gether, and to the fides of the furnace, quite
choaks it up, and, by its tenacity, hinders
the metallic parts from finking downwards,
as they would do by their natural gravity.
What is chiefly wanted in fmelting, is an o-
pen fire; the furnaces are commonly (diffid¬
ently clogged with the fiony and other he-
trogeneous bodies united with the ore, which
run into glafs without the addition of any
fuch foreign matter as has a tendency to vi¬
trification. The char’d wood, on the con¬
trary, keeps always an open fire, the in¬
flamable
236 ESSAYS and OBSERVATIONS
flamable part of which is fo far from hurt¬
ing metals, that it preferves their malleability,
by fupplying with its own fulphur that which
is deftroyed or carried off from the metal,
by the intenfe heat employed in the fmelt-
ing ; and this is fo far true, that iron redu¬
ced to a calx or friable fubftance by calcina¬
tion, has its malleability reftored by being
fluxed with powdered charcoal only. And this
t"S •; - , . — , —1 . . ** r' m » * '
we may here obferve, by the bye, as an in-
fiance of the difference of ftibftituting a vege¬
table in place of a mineral fulphur.
The peat then being intirely a vegetable
fubftance, there feems nothing more requi-
fite to make it a proper fewel for fmelting
iron, but the being able to raife by its means
a heat fufficient for that purpofe. This, ex¬
perience fhe'ws, cannot be done with the
peats we ‘now have. The moil likely me¬
thod of obtaining this end, I think, is, to
bring them to be as folid and compact a fub¬
ftance as poftible. The denfeft bodies, tee-
teris paribus , when thoroughly heated, are,
the hotteft: hence it is, that metals as they are
the heavieft bodies, fo they reach the great-
eft degree of heat. The fame holds in fewel $
the hardeft woods are made choice of,
when
■ f v T 4
PHYSICAL and LITERARY. 237
when a ftrong heat is wanted 5 and even in
common peats, I have (hewn you how far
preferable the hard and folid are to the light
and fpungy. By fame experiments which I
have made, I find it to be no difficult mat¬
ter, to bring peat to a confiderable degree
of folidity, as you yourfelves may fee by the
fpecimen I now fliovv you. The Ample o-
peration of grinding, does the bufinels ; and
as a peat, when taken out of the mofs, is a
foft body, and eafily grinded, a machine may
be eafily contrived to grind, at a moderate ex¬
pence, feveral tuns in a day. The charge
of digging peats, cutting them into fquares or
the form of bricks, when of a proper dry-
nefs, will be little different from that of ma¬
king peats in the ordinary way. The foli¬
dity of peat prepared in the manner menti¬
oned is furprifing ; its fpecific gravity being
fomewhat greater than that of pit-coal. I
compared a peat of this kind with a piece of
coal brought from Baron Clerk's coal-mines
near Edinburgh , and by the hydroftatical ba¬
lance, reckoning water 1000, their fpecific
gravities were nearly as follows, pit-coal
J23y, folid peat 1303.
From
23^ ESSAYS AND OBSERVATIONS
From what has been faid, it appears, that,
if iron could be made with peat, it would be
of great fervice, particularly in fome places
of North Britain , where peat is to be
had in plenty, along with iron, which now
lies unwrought for want of wood : and even
where wood may be found, if peat brought
to the confiftency I mention would do the
bufinefs, it would come cheaper than char’d
wood. Another advantage of this kind of
peat, would be the fmelting of lead with it
alone, which cannot well be done at prefent,
without the help of pit-coal, which in fome
places mu ft be brought from a confxderable
diftance, and at no fmall charge,
- The other ufe I would propofe of peat, is
the employing it as dung, for the fertilizing
of ground, when prepared in the manner I
fli all afterwards mention. I am not igno*-
rant, that the afhes of peats are ufed for that
purpofe with great advantage, not only by
themfelves, but likeways mixed with other
dung ; and even the duft of peat, that re¬
mains at the bottom of peat-ftacks ; but in
that ftate it has not the effects of dung, nor
are its effefls equal to what they would be,
were it rightly prepared. Tofet this matter
PHYSICAL and LITERARY. 239
in a proper light, I mu ft be allowed to fay
fomething in general of vegetation, and of
the ufe of dungs in promoting it.
Vegetables which increafe by feed, as is
the cafe with by far the greateft part, if not all
of them, are at fir ft plantulas wrapt up in a
' very lmall bulk in the end of the feed ; which,
when put in the ground, by the moifture
they find there, extend themfelves, and are
firft nourifhed by part of the feed itfelf,
which does the fame office to the young plant,
by affording it a finer nourifhment, as the
place?2ta does to the embryo . When the plant
becomes ftronger and fhoots forth its roots,
it then draws its nourifhment from the earth.
Thus it goes on growing until it has attained
its utmoft perfection : after which it gra¬
dually decays, dies, and at laft rots and pu¬
trefies. By putrefaction, the parts of which
the vegetable was compofed, viz. its falts,
oils, phlegm and earth, are feparated : part
remains upon the ground where the plant
falls ; but the far greateft part being volatile,
flies up into the air, from whence it defeends
again upon the earth and incorporates with
it. The fame materials ferve to nourifh new
plants, there being no part of them, as we all
know.
540 ESSAYS AND OBSERVATIONS
know, loft. What we call a vegetable
mould, is an earth in which there is ftore
of fuch parts of vegetables lodged, the ma¬
trix in which they lie, being a fine but bar¬
ren fand. As long as there is a fufficient
ftock of fuch particles in any earth, that
ground is fruitful 5 but when this is exhauft-
ed, which happens fooner or later, from the
quantity of vegetables nourifhed by it, and
carried off for the ufes of life, it becomes
barren. The only remedy, when no better
can be had, is to allow it to reft, until it re¬
ceives a new recruit from the air, in which
are perpetually floating, and falling down up¬
on the earth, particles of all kinds, proper
for the nourifhraent of plants. But as this
is a tedious way of recovering the fertility
of ground, the better and more expeditious
one, is by laying dung upon it, which being
wholly made up of putrefied vegetables, or
animals, equally proper for nourifhing plants,
the parts, of which both are compofed, be¬
ing the fame, and the tranfition from the one
to the other eafy 5 the ground by this new
acquifition becomes again fertile. Every ve¬
getable then whofe parts are fet looie, by
that laft fermentation of nature, putrefaction,
affords
PHYSICAL and LITERARY. 241
affords a proper pabulum for vegetables ; and
the great didin&ion of plants, which com¬
monly lies in a very if mall part, and that too
the mod volatile, being taken away by pu¬
trefaction, all vegetables, when reduced to
that date, feem to be pretty much upon a
par for that purpofe. Now, to return to
what I intended to fay, and to which what
I have mentioned was only a kind of pre¬
amble ; Peat mofs, being wholly a vege¬
table matter, mud, if reduced to a thorough
date of putrefaction, anfwer the fame pur-
pofes for fertilizing ground as otherf utrefied
vegetables. While it lies in the mofs, there
is too great a quantity of water, to raife ja
fufficient degree of heat, to bring the ve¬
getables of which peat-mofs is compofed,
whether actually growing, decaying, or de¬
cayed, to a compleat degree of putrefaction.
But if it were taken out of the mofs, and laid
in heaps like other vegetables to rot, with a
degree of moidure fuitable for that purpofe ;
and if, to begin and alfo quicken the putrefa¬
ction, green frefh fucculent plants were em¬
ployed in a fufficient quantity fird to raife a
heat 5 this I make no doubt would, by commu¬
nicating it to the moffy fubdance, in a fuitable
Vol.IL Plh time,
242 ESSAYS AND OBSERVATIONS
time, and by right management; reduce the
whole mafs to theftate defired. This alrea¬
dy is in fome meafure pradtifed in Hollandy
where they mix the duft of peats with ordi¬
nary dung, in making of dung-hills.
1 fhall conclude this paper with only men¬
tioning two others ufes of peat, which I had
almoft forgot, viz. that peat-duft ftrawed up¬
on ground where peafe or other feeds are
fown, in order to have an early crop, is an
excellent prefervative of fuch vegetables from
the froft ; as it keeps the ground warm, by
not allowing the cold to penetrate into it.
And that there is nothing properer than peat
to flop water, and to confine it, in the making
of fifh-ponds, &c. This I learned from his
Grace the Duke of Argyle , who I obferved
ufed it with great fuccefs for that purpofe.
Art.
PHYSICAL and LITERARY. 243
f
Art. X,
The EffeBs of Semen Hyofcyami albi* by
Dr . Archibald Hamilton Phyfician in
Edinburgh
- - — — - — Student of phyfic* of a thin
habit of body, about twenty years of age*
had been* for two years, in the ufe of taking
a fmall quantity of white henbane-feed to
make him deep* and without any bad effedt.
But on Friday March the 8th 1754* betwixt
four and five in the afternoon, he* in order to
procure deep* fwallowed about twice as much
of this feed as he could take up betwixt his
fore-finger and thumb* /. e. nearly 25 grains*
He felt himfelf half an hour after* very heavy
and much inclined to deep 5 his eyes were
oppreded, and fpirits dejedted, with a general
laffitude and inactivity over his whole body*
Thefe fymptoms dill increasing, he went
abroad and drank tea about fix o'clock 3 and
with great difficulty could keep awake* ha¬
ving fometimes let fall the tea-fpoon infenfi-
bly. He complained of a great uneafinefs
and
* May i» 3755.
244 ESSAYS and OBSERVATIONS
and drynefs of his throat, and that the tea
in fwallowing was like to choak him. He
had aifo fame gripes in his belly. After he
drank tea, he was foon feized with convul-
fions and fo great a degree of infen Ability,
that he did not know the people who were
in company with him. He fpoke many in¬
coherent things, and at the beginning of his
ilinefs faid he was afraid he had taken poi-
fon. The people who were with him be¬
ing alarmed, ordered him to be carried home,
and fent for me. I found him incapable of
giving any account of his misfortune. His
eyes were open and rolling, now and then
he was feized with tremors, ftartings, and
convulfions, grapling the bed -deaths, his
head, face, nofe, and other parts of his bo¬
dy, in the manner patients frequently do in
nervous fevers. His pulfe excenively fmall
and low with fubfultus tendinmi . The fenfe
of feeling feemed alfo impaired , for when
I pinched his fkin, he made no complaint.
He had no inclination to vomit, nor had any
(tool from the time he took the feed. I or¬
dered him immediately a vomit ; and in the
mean time Dr. Bojwell was fent for. He fpit
out the vomit as foon as it was poured in-
PHYSICAL and LITERARY. 245
0
to his mouth ; fo that it appeared he was ei¬
ther not deprived of tafte, or could not let
the vomit over. A fecond vomit was in-
ftantly given, which was alfo fpilt or fpit out.
A folution of white vitriol was afterwards
given, the moft of which he fwallowed with¬
out the defired effedh A ftrong clyfter with
antimonial wine was adminiftred, which he
kept about twenty minutes. He got a fecond
injection an hour after. As he continued in
the fame miferable fituation, a blifter was
applied to his head, and finapifms to the
foies of his feet. He paffed the night in the
fame condition without fleeping, and was
alternately feized with convulfions, ftartings,
and catched with his hands at every thing
about him. In the morning, he became
more fenfible, and began to fpeak a little
diftinitly, altho’ his head was yet very con-
fufed and muddy. He told what quan¬
tity of the feed he had taken, and for what
purpofe. His pulfe was now fomewhat
ftronger. He got a purgative infufion,
which operated four times that day. In
the evening, he wras ftiil more diftindf,
aliho’ bis eyes continued heavy and his
head
246 ESSAYS and OBSERVATIONS
# ^ /
head confufed. His pulfe was now quick*
full, and ftrong ; and he complained of
a great pain and weight in his head. He
was blooded about twelve o'clock that night
to the quantity of twelve ounces. He
fweated plentifully* had good deep* and
was altogether fenfible and diftindt next
iporning.
Art.
PHYSICAL and LITERARY a 247
Art. XL
The Effedls of the llhorn- Apple , hy Dr. Abra¬
ham Swaine Phyfcian at Brentford
RObert Bulmer, a man of a ftrong con-
flitution, 69 years of age, and who
had enjoyed a good ftate of health all his life,
till about two years before, when he was firfl
afflifted with the gravel , in Offiober 1746,
being advifed by a friend to take a deco ft ion
of the fruit of the common burdock, as a
remedy for his difeafe, by miftake gathered
the fruit of the ftramonium or thorn-apple.
After dividing three of thefe, each of which
was as big as a fmall hen’s egg, into twro
parts, he boiled them in a pint of milk,
which, when a little cooled, he drank off a~
bout eight o’clock in the morning falling.
Prefently afterwards, he became vertiginous
or giddy ; and therefore rofe from his chair
to take the air, with an intention to pluck
more fruit. In walking two or three hun¬
dred yards from his houfe, he daggered as
. if
* May 1. 1755.
248 ESSAYS and OBSERVATIONS
if drunk, feared he fhould fall on his head,
and that he was about to lofe his fenies ; but
had no ficknefs nor the leaft inclination to
vomit. As foori as he got home he went to
bed, and complaining of an exceflive drynefs
of his tongue and throat, a little water mix¬
ed with wine was given him ; he alfo felt
an odd fenfation of drynefs in and violent
girding a-crofs the thorax . In lefs than half
an hour he began to fanlter in his fpeech,
became infenfible, reftlefs, and muttered fre¬
quently ; in which condition I found him.
His extremities, and alfo the trunk of his
body, were cold. His pulfe fmall and quick*
He often raifed himfelf on his knees, con¬
tinually ftretched out his arms, and employ¬
ed his hands as if fearching for fomething he
wanted ; his eyes were dull and heavy > af¬
ter fome time, he became dumb and more
quiet, had almoft no pulfe ; and, upon his
being taken out of bed that it might be put
into better order, his limbs were vifibly pa¬
ralytic. Altho5 he changed poftures a little,
yet he remained flupid for fix or feven hours ;
then he raged furioufly, requiring two per-
fons to hold him in bed, notwitbftanding
which, he raifed himfelf up, tolled greatly,
and
PHYSICAL and LITERARY. 249
and feemed to catch at the by (landers with
his hands, uttering incoherent fentences. At
laft he became fenfible and more quiet, refl>
lefs and delirious by turns ; and about ten
o’clock in the evening of the fame day per¬
fectly recovered. After taking a purgative, he
flept well all night, and had feveral (tools in
the morning. For the fpace of fourteen
hours he neither flept, vomited, nor difchar-
ged any thing by (tool or urine, tho’ he fre¬
quently pafles urine at other times, being grie*
voufly afflicted with the gravel.
Vol. II. I i Art.
ISO ESSAtS and OBSERVATIONS
Art. XII.
The EffeB of Mujk in curing the Goiit in the
Stomach ; by James Pringle j Efquire,
Jate Surgeon to the third Regiment of
Foot-Guards**
A Gentlewoman, aged 43 years, natu¬
rally of a delicate conftitution, who has
been for feveral years fubjed: to hyfteriq
fits, attended with a dry afthma, which her
fhape much contributed to 5 was frequently
attack'd to a violent degree with the gout in
her head and ftomach, as well as in all her
extremities $ and with which fire was lame the
mo ft part of Summer 1745. On the 3d of
November following, (lie was violently feized
with it in her ftomach, which occasioned
violent hiccups and convulfions of the part.
The defcription fhe gave of it was, that as
foon as thefe fits feized her, there came on
a violent working of her ftomach, and fo
great an agitation of her back, that her Maid
was not able to keep her hand on it. By
degrees
* Aprile 3. 1746.
PHYSICAL and LITERARY. %$x
degrees it rofe to her throat, when fhe was
almoft ftrangled. She , could by no means
lie down, but was forced to fit night and
day in an eafy chair; and even then if fhe
lean’d her head to the one fide or other, it
gave her great pain fo that fhe was obliged
to fit in an eredt pofture. , Her legs were
very much fwelled, which fubfided a little
on laying them on a chair ; but as foon as
that happened, the afthma returned. She
did nothing all this while but keep herfelf
warm, now and then drinking a little of
fome generous wine (as fhe faid, to keep
it out of her ftomach), and once or twice
took a little of the tinbl. facr a. On the 21ft
of November about 9 o’clock at night, a
Lady of her acquaintance, who had feen her
in this condition, defired me to vifit her,
tho’ fhe doubted if I fhould find her alive.
Accordingly I went, and as 1 had feen fuch
extraordinary effedts of the tonquin medicine
in the Jingultus , and had heard from Mr.
Read of its efficacy in other nervous cafes, I
imagined it might be of fome fervice here :
and therefore I fent her the following bolus.
R Cinnab .
25J ESSAYS AND OBSERVATIONS
ffA *■ 4. * / ■
Cinnab. natlv .
— - Antimon. aua gr. xxv,
Mofch . opt . gr. xvi.
‘ aS)t. q.j\ F, bolus .
r * ~
But altho’ this is Mr. Read's common
dofe, yet, as fhe was very weak, I ordered
her to take only the one half of it imme¬
diately, drinking after it a cup of brandy,
•*
and the other half in fix hours after. Next
morning I found her much better, having
from the firft dofe no more convulfions in
her ftomach. I then ventured to give her
a whole bolus at 9 o’clock in the morning*
to be repeated every four hours until fuch
time as fhe fihould fleep or fweat: and not-
withftanding the coldnefs of the weather,
and her being obliged to fit in a chair, yet,
by the time fhe had taken four bolufes, a
plentiful fweat and fleep enfued, and then
file was able to lie in a horizontal pofture on
her couch without the return of her former
fymptoms. This fweat continued from the
afternoon of the 22d till the 24th at night,
with very little intermiffion. I gave over
the bolufes and ordered her a julep, to eight
punces of which I put twelve grains of mufk,
PHYSICAL and LITERARY. 244
to be taken ad libitum . In this method (he
continued till the 27th, quite eafy and free
from all her former fymptorits, and even the
fweliings of her legs almoft gone : But as on
this day fhe fancied the gout in her ftomach
was returning, I gave her another bolus.
She complained this time of the intolerable
heat of the brandy, which was the fxrft thing
(lie had found warm in her ftomach during
this illnefs. On the 29th, fhe was appre-
henfive of another attack, and took another
bolus * after which fhe found herfelf very
Well, and walked about the room, the fwei-
f- { ** r \ i *4 '• W ( f ■' t A i: : » . •’
lings of her feet being quite gone. And on
*
the 4th of December went out in a chair to
thank the Lady who fent me to her, and
continues to be well to this day.
Art.
254 ESSAYS AND OBSERVATIONS
,r>
fj im 1 v
* < i
Art. XIII.
-A 'w* . - - V ~ 4. i ... > * ...... ....
Account of an uncommon Effect of antimo ■-
nial wine ; by Dr. James Walker Sur-
» ■ ■ '
Agent Jor the Navy at Ed in-
burgh*. •
O-
J. ' „
THE vinum bene di Bum is univerfaliy
known to be a ftrong emetic, when
given in a large dofe $ and it has alfo been
often prefcribed in fmaller quantities as au
attenuant, fudorific, and diuretic : but an
accident lately difcovered to me a very diffe¬
rent effedt of it, from any of the above
mentioned.
V ■ X *v
Being one evening, in December 1 7553
a little hot and feverifh, with a quick and full
pulfe, I went early to bed, and drank a full
Dnglijh pint of fack-whey which I had order¬
ed one to make for me. Very foon after
this, I fell afleep, and continued all night
oppreffed with an unufual drowfinefs : at ten
next morning, I with great difficulty got fo
far the better of this lethargic difpofition, as
to
* February 5. 1756.
PHYSICAL and LITERARY. 255
to get out of bed ; when I found myfelf ftill
heavy and inclined to deep, with a laffitude
and numbnefs in my limbs, fo that I could
fcarce ftand. Being thus incapable to go a-:
bout bufinefs, Irefolved to ride out. on horfe-
back ; and having mounted with fome diffi¬
culty, found my head very giddy, and had
much ado to keep myfelf from falling afleep.
After having rode three hours, I returned
home much in the fame fituation, and was
furprized to find two apprentices with the
fame complaints I had myfelf : they could
affign no caufe of their being fo affedled, nor
had they eat any thing but their ufual food,
except the curd of which I had got the whey.
Being led by this to fufpedt fomething un¬
common in the wine with which the poflet
was made 5 I called for it, and had a bottle
brought me containing evinu?n benedidtum ,
which had been made about a month before;
and the bottle having been put in an impro¬
per place, was the reafon of its having been
miftaken for Lijbon. I found I had drank
in my whey about a gill and a half of this e~
metic wine, and was furprized it had not vo¬
mited me ftrongly. Thinking, however, that
the finely attenuated particles of the antimony
might
?5s ESSAYS AND OBSERVATIONS
f /
might be moftly fufpended in the curd, I
inquired particularly at the two young Gen¬
tlemen who had eat it, whether they were
affedted with any naufea or vomiting ; but
they told me they found no other effedt but a
heavinefs and great inclination to deep. This
drowfinefs continued with them two days ;
but I did not find myfelf quite free of it at
the end of four days. I do not know if it be
worth while to obferve, that the day after I
had drank the above whey, my pulfe was ten
in the minute flower than it had been the
night before. It may be proper however to
take notice, that the vinum benedidium which
was ufed, by miftake, inftead of LiJbon> was
made exadtly as is diredled in the Edinburgh
Difpenjatory 3 and I have fince found half an
ounce of it vomit a patient very well.
• .. -• r . . , • . .. , • . - ... . ’J;. ■
- , ■ Art.
'I
PHYSICAL and LITERARY. 257
j * r » r r
Art. XIV.
An ohjlinate Dyjentery cured by Lime-Water $
by James Grainger M. D. Pbyfician at
Lori cion ":K
) 4 7- ; •
«
’ \ ( \ l •* t
- - —'Arfdak, a flout, middle aged, but
intemperate foldier, was feized November
1751 with fhivering and other fymptoms that
precede an accute diforder. The day fol¬
lowing, he went frequently to ftool, and e~
vacuated blood to the quantity of a gill every
quarter of am hour. Tho’ the fever was in-
confiderable, yet, as he was of a fanguine ha¬
bit, the lancet was not fpared. ;He fwa Howl¬
ed feme ipecacuan vomits * was gently pur-
• t t . -
ged every third day with rhubarb ; and had
fmall quantities of opium at bed-time to hin¬
der his rifmg in the night. The third week
his fundament came down, attended with
T * •> j. *
but little pain, unlefs when he went to flool.
This fymptom, however, was tinreoufly re¬
moved by fomentations of a decodlion of oak-
bark. December ; his flools, tho’ lefs frequent,
were mixed with blood and mucus. Then
VoL.II. Kk the
* May 3. 1753.
2fS; ESS AY S and OBSERVATIONS
« I
the gripes feized him in good earned:, fome-
times fixed and torturing like a flitch in the
baftard ribs, at other times wandering with
borborygmiy now as it were twilling his guts,
then cutting him in two, as he exprefled it,
and bending him forward. They were al¬
ways mod fevere before ilool, eafier in the
time of evacuation, but eafieft after. With
< ■
thefe fymptoms were complicated a dyfury
and piles, greatly inflamed, but bleeding
none. Thefe difmal complaints continued
aim oft equally violent for three months, altho’
V. S . emetics, *vitr, antimon . cerat . mild an-
tiphlogiftic purgatives, opiates, lubricating and
aftringent remedies were ufed, as the fym-
ptoms indicated. Opiates, tho’ they eafed
him, feldom procured undifturbed repofe, and
always affedted his head 5 this eonfequence
of laud . was more effedtually prevented by
half loeafeL than any thing elfe. Vomits
always, relieved him, but increafed the pain
*
of the haemorroids. Aftringents, tho’ they
bound him up for a little time, moft gene¬
rally brought on afterwards a more frequent
inclination to Ilool, with increafed tormina .
Clyfters were impradlicable on account of the
piles, but he found considerable fervice from
the
PHYSICAL and LITERARY, 259
the milder purgatives, with calomel. ; afid
when the fwelling of his fundament was re¬
moved by fulphur * and emollient, difcutient
applications, they became highly ufeful. In
the 4th month, the region of the ftorriach
fwelled, with rednefs of his face, efpecially
after food, and continued for fix months, aL
tho5 its removal was attempted by bitters.;
and the bark (cautioufly combined with pur¬
gatives), mulled claret, and camomile tea,
while proper external applications were not
forgotten. April and May , the haemorroids
and dyfury left him ; but his ftools became
thinner, more acrid, and intollerably fetid.
Then he Was feized with a hiccup, his face
looked ghaftly, his extremities turned cold,
his pulfe became quick, /mail, irregular, and
his gripes were rather abated. Evacuations
in thefe deplorable circumftances were im¬
proper, but finapifms were applied to the foies
of his feet ; and epifpaftics to the region of
the ftomach with feme fuccefs. A bolus of
bark, caftor, and camphire was given every
third hour, and walked down with a glafs of
mulled claret ; his guts too were fomented
with anodyne, emollient, and . antiseptic cly-
fters. By thefe his deadly fymptoras left
him.
a6o ESSAYS and OBSERVATIONS
hita, he could lit up at the fire, and had
not above 12 {tools in the 24 hours, which
were however fiili ichorous. I could not
find from the nurfe that he ever paffed any
of the villous coat of the guts, tho’ jcybala
were frequently evacuated. About the end
of - May, he was able to walk round the ram¬
parts of Fort- Willi am , and he told he thought
he would recover, were he fent from Loch-
aber . On this, he was carried, by water,
to the Ifle of Mully being provided with pro¬
per medicines to forward his recovery.
Here, tho* the hiccup and facies hippocratica
did not recur, yet his gripes did 5 and he
purged blood and worms almoft inceffantly.
The latter end of July , he was fent back to
the Fort a perfect fkeleton; where, tho’ I
am convinced the air is inferior to that of
Cajlle-Dowart in Mull, yet, as great care was
taken both of his diet and medicines, he paf¬
fed no more worms, his gripes only feized
him at ftool, whither he went much more
feldom than formerly 5 what lie paffed now
appeared to be mucus mixed with pus and
ftreaks of blood. Very fmall dofes of ipeca-
cuan, viz. eight grains three times a day were
fh^n adminiflred to him every third . day 4
hut
PHYSICAL and LITERARY. 261
bat, tho’ they relieved by operating both up
and down, yet they ficlcened him fo much,
that I was obliged to fubflitute a bolus of
calomel, over night, and a purgingptifan next
morning, in their place. The difeafe, how¬
ever, did not yield 5 and when the regiment
was ordered to march for Berwick upon
Tweed, he was put aboard the veffel that
carried our baggage. This was a hardy ftep,
confidering his weaknefs, and the length and
danger of the voyage ; but he could not be
carried with his comrades over the Black
mountain, and he defired to die any where,
rather than remain in Fort-William . Five or
fix weeks after he landed at Berwick , his
ftools were more numerous, and Fill very
painful. Sometimes blood, fometimes dime,
fometimes ichor, and once he palled a great
quantity of hardened excrements, which re¬
lieved him of a dull pain of his left hypo-
chondre ; his legs too, at night, fwelled
and pitted to the touch, and his ftomach was
often inflated. Bitters, with Reel, were
prefcribed, and camomile tea drank for
hreakfaft, while the utmoft regard was
♦
had to diet ; the vitr. antimon . was again
tried, and alum poffet recommended. The
dyfentery
£62 ESSAYS AND OBSERVATIONS
dyfentery baffled all. our attempts -^and'now,
defpairing of his recovery, I ordered him to
drink lime-water, with a third part milk, to
the quantity of an Englijh pint and a half every
day : It was at the latter end of 'November
1752. In three days time, there was a fen*-
fible change to the better, his ftools were
left frequent, and his pains abated. Encoura¬
ged by this happy beginning, he was ordered
to drink lib . iii. of lime-water a-day; This,
in three weeks, made him fo coftive, that I
was obliged to clyfter him, and diminilh the
aq. calc, to the quantity firft ordered. In fix
weeks from his taking this medicine, he was
fo thoroughly recovered, that he was difmif-
fed the hofpital, and foon after marched to his
company at Carlifle , where he {till enjoys
perfect health. The diforder was on him
full 14 months ; and I have reafon to think
his recovery was chiefly owing to the lime-
water, after the moft celebrated antidyfen-
terics had been ufed in vain.
The dyfentery is endemic at Maryburgh ,
near Fort-William , and commonly attended
with procedentia ani , piles, dyfury, abdomi¬
nal inflations, cidemds , and hiccup. Many
of the foldiers died, efpecially the more, inn
temperate ;
PHYSICAL and LITERARY. 263
temperate ; between the 20th and 35th day,
is the fatal period. Thofe who died had
mortifications of the great guts : it began
with us about the latter end of Qffiober ;
autumn however is its ufual feafon 5 it rages
commonly two months, tho’ many have it all
the winter, and I always obferved them worft
■i- W w
in rainy weather. It may be worth while to
obferve, that of late lime-water principally
conduced to cure an Officer of a dyfentery,
while another was effectually cured of a
weaknefs in the bladder, by the fame re¬
medy.
) ,
L >
;
. S'
• •• \ ,
Art,
464 ESSAYS and OBSERVATIONS
f y r * - „
** v- *% ••• * s •. *, • ' ’ — . f- ^ iv ' . 4» ... . . ,
<* f t {; i 1 ( r < ! . • , <' J *
V <, ? . ' ' '■ ' '• J ■
\ try ' x t ; J r ' f
* • * .. : , l * \ •
Art. XV.
’• ' > • ■ - • • ■: ; .v ■ * ' - '} ‘ - ; ; : v> • • . f
The anthelmintic Virtue of the Bark of the wild
Cabbage or Bulge-water Tree ; by the late Mr <
Peter Duguid late Surgeon in Jamaica,
in a Letter to Alexander Monro Jenior s
M.D. & P.A.
‘ ' ' • - > i ■ •• A i 'i ’ > •• • ’ / v’.V; i ■ ' < [
%•
'it . • "
THE Writers on the difeafes of the
Weft-Indies generally take little notice
of the Inhabitants of Jamaica , young and
old, white and black, being much troubled
with worms, efpecially the long round fort.
They are however fo frequent, that every
pra&ifer ought to have regard to them in
treating mod of his patients. I imagine thefe
worms infeft the inhabitants here on account
of their fweet vifcid bread-kind, to wit, plan-
a
tains, yams, bananos, fweetifh potatoes, &c .
which are fit nourifhment for thefe vermin.
I was lately allowed to open a Gentleman’s
child, that, at feven months of age, died of
vomiting and convulfions. In its inteflines
there were twelve large worms : one of
them
* May i. 1755.
PHYSIC A L and LITERARY.
them filled the appendix vermiformis , and
three of them were intertwifted in inch a
manner as to block up the opening at the
vahitla Tulpiiy lo that nothing could- pais
from the imaJl to the, great guts.
Nature has bountifully provided the
people here with a powerful remedy again ft
io great an evil. This is the bark of a tree
growing plentifully in this Ifland. The in¬
habitants call it wild cabbage of bulge-wafer :
and from what I have feen, it appears to be
the moft powerful vermifuge yet known ;
for it frequently brings away as many worms
by ftool as would fill a large hat. It is
commonly given in decodion, but not in
any regular quantity; the negroes being
generally the preparers of this medicine,
and therefore no wonder that it fometimcs
- n
has very violent effedts. I am now making
experiments for afcertaining the dofe to pa¬
tients of different ages, and fhall foon fend
you the refult of my trials, together with
fome of the bark itfelf.
Vol. II’.
LI
Art.
%66 ESSAYS and OBSERVATIONS
Art. XVI.
Fhe defer ipt ion of a tmnftrous Foetus 5 by Mr*
John Mow at Surgeon at Langholm, in
a Letter to Alexander Monro fenior,
M. D.& P. A
t , -* c* ~ . • 4 f * * .V -- -4
_ * \ . ; j X > - . . \r . 1 ... . v
SEveral learned men having of late years
difputed about the formation of mon-
, i '■ ' ■ ■ t ' ''
fters, it is probable the hiftories of them may
be of ufe in accounting for fome phenomena
in nature ; on this account, I fend you the
following defeription of one, which will be
better underftood by the figures-which young
Profeffor Monro caufed to be drawn of it, of
half the natural dimenfions. See plate VI.
Mh f :
- - when fix months with child,
had this abortion, which lived half an hour.
' •' » i •• i J - -J" . . Am-
Tab. VI. fig. 1. A A The lower parts of the
bodies of two female feetufesy with their low¬
er extremities in a natural ftate.
B The navel-firing common to both fee -
tufes .
C The bodies joined immediately above
the navel.
DD The
* May i4 1755.
PHYSICAL and LITERARY. 267
D D Thefuperior extremities of the more
compleat jcetus , which is here reprefented
moil in view.
d d The fuperior extremities of the other
foetus. All the four being of a natural form.,
E The fternum of the more compleat foetus
which had clavicles joined to it in the com¬
mon way, as the other alfo had.
F One neck common in appearance to
both fcetufes.
The face and ears, being natural, need
no letters of reference to their parts.
G The forehead had hair farther down,
than ordinary.
H The top of the head of an extraordinary
breadth.
I The hairy fcalp covering the parietal
bones.
K The right temple of the foetus D D.
L The teguments covering the occipital
bone.
M The occiput of the other foetus .
Fig. 2. The back view of thefe fcetufes
where the head, neck, and fore parts of the
thorax only are reprefented.
N N The fcalp over the four parietal
bones.
O O _
2<58 E.SSAYS and OBSERVATIONS
Q Q^ The two meatus auditorii.
having nothing preternatural. Where the
e- r ' * V ~ c \ ’■ »’
abdomen of each feet us was diffinft at A' A,
« • ’ ' • r
the vifeera were In a natural ftate, and in'
_
the undivided cavity of the belly above Cs
only one omentum and one pancreas . One dia¬
phragm divided the abdomen from the thorax ,
but it was pierced by two venue cavee and two
aefophagi , and two 'aorta dejeendentes paffed be¬
tween its appendices on each fide where the
vertebrae were.
There was a Jiernum to the thorax of both
flues . i . ana t Jig. 2. From each jiernum
a mediaflinum vvas extended to a ligamentous
fiefiiy iu Dilance 3 which was continued tranf-
yerfejv from one fpine to the other. In
■ 1 • . „ , ■ . •
each
PHYSICAL and LITERARY. 26#
each mediaftinum was a pericardium, with its
heart and veflels as in natural fcetufes, and
on each fide of each mediajlinum was a
thorax with lungs. Thofe in the thorax
of the more compleat child, the one, to
wit, with the face, being of a pale colour and
fwimming when put into water, while the
other lungs were of a redder colour and fank
in water.
The fpines gradually approached each o-
ther as they extended towards the neck, ' at-
the lower part of which the fides of the bo¬
dies of the vertebrae feemed to be contiguous *
but I pufhed a probe up between them as far
as the fecond vertebra .
Within the head I faw a cerebellum on
each fide divided from a common cerebrum
by a membranous plexus produced from the
dura mater . The parts of the 1 encephalon were
too foft and tender for my difleition, and I
examined the anatomy no further, but have
the monfter in fpirits with the three great ca¬
vities filied with lint and bran where the
bowels were taken out.
Art.
1
%7o ESSAYS AND OBSERVATIONS
r * v - , * «A t
< •• \ ■ « ' ' '.V \ f .V, ' < *\ •'
l.v. > » ■ \
r ... v •• ^ r ' * ... ~ - • •. -*
|r\ r# f\ "i ^ ■ ’ 5 f f . * "*.. * "> -* * *
Art. XVII. . 1 , •
* ♦r-., *» *\ *•* •* C " * ' , '* i >l - * * ■■ y- •! -
«f *i ' - * ’
\The DiJfeBion of the fame Monfler continued ,
by Alexander Monro junior, M. D. and
Profejfor of Anatomy in the Univerfity of
Edinburgh^. ...
MY father having fhewed me Mr.
Mowaf s defcription of the moiv
ftrous foetus y and a model of its form in wax,
I was curious to know how the parts of the
head and neck were formed. The prefer-
ved foetus was obtained with difficulty, and
under a promife that no diffedtion ffiould be
made which might fpoil its form. The fub-
jedt was unfavourable, and the promife ren¬
dered the diffedtion difficult, and impoffible
to be performed fo accurately as I wifhed.
After drawing afunder the two parietal
bones of each fide INN (fee Mr. Mowaf s
fig.) to take out the lint, &c, with which
the fkull was filled, and having cleaned a-
way the matter, membranes, &c. adhering
to the bones, I favv the cranium of a natu¬
ral
* May i, 1755.
PHYSICAL AND LITERARY. &71
ral form on that fide where the face is, fo
far back as th t fella turcica , behind which
the ends of the cuneiform proceffes of the
two occipital bones united together. From
each of thefe cuneiform proceffes the occi¬
pital bones extended of a natural^ enough
form to each fide ; their fitiiation may be
judged by confidering the figures at L, M,
or O, O, having each a j or amen magnum for
the fpinal marrow. At the fide of each of
the occipital bones, neared to the conjoined
preternatural ears, an os petrofum was placed,
but without having any fquammous part of
the temporal bones, fuch as were on the o-
ther fide of each occipital. Between thefe
ojja petrofa there was a triangular little bone
which fuftained thefe preternatural ears,
and was inftead of os ethmoides , fphenoides ,
and two fquammous bones. Th t foetus with
the face had therefore all the common nerves,
but the foetus with only the conjoined ears
wanted the 1, 2, 3, 4, 5, and 6 pairs.
The meatus Q, Q Jig. 2. led into the organ
of hearing. The orifice R was the entry to
a paffage which opened into the cefophagus of
the foetus D D,
The -
z72 ESSAYS AND OBSERVATIONS
The mouth of the more com pleat foetus
had all the ordinary parts, with the uvula ,
nares , larynx and pharynx . Behind this pha¬
rynx. and the afophagus defending from it,
there was another larynx and trachea . From
the back part of the glottis of this laft menti¬
oned larynx , a little excrefcence refembling
a tongue flood out, and behind it a canal de¬
fended of the form of one of the nares which
joined with the one continued from R to
form another cefophagus .
I could not profecute the veffels and nerves
placed on the neck and head without breach
of promife, and therefore can give no ac¬
count of them .
Art,
PHYSICAL and LITERARY. 273
Art; XVIII.
' • * • ■ : ' 7 • * . ' f‘ »: ’ I .1
Bones found in the ovarium of a Woman 3 by
Dr . George Yotjng, and communicated
to the Society by Dr. John Boswell, Fel¬
low of the Royal College oj Thyficians in
Edinburgh
A Woman near fifty years of age, who
IjL had never had a child, * being four
months obflrudted, thought fhe had con¬
ceived ; but the menfes then returning, fhe
had exceffive flooding, which was fometimes
in great quantity, at other times was lefs,
but fcarce ever intermitted for a year and a
half. It was then flopped by feme medi¬
cine ; after which, her belly fwelled to fucfl
r *- • -* — s r
a decree in fix weeks, that her urine was
c
almoft totally fupprefied ; flie was very co~
ftive unlefs when clyfters were given, and
fhe died in a few days more.
On cutting the teguments of the abdomen ,
a large quantity of bloody water ruffled out;
and when the containing parti were fully
Vol. II. M m opened,
* November i. 1737*
a 74 ESSAYS and OBSERVATIONS
opened, all the cavity was bloody, and the
veffels were large and turgid with dark-co¬
loured blood. No bowel was now feen 3 all
*
that appeared in view being a great number
of irregular flefhy lumps, which were blad¬
ders full of a red watery liquor. Some of
them were of the fize of the larged apples
I have feen, others were as fmall as pigeon-
eggs 3 and there were of all the interme¬
diate iizes between thefe. Upon a ftridter
examination, thefe veficles were found to be
all contained in one common cyft, of which
I had cut the fore-part with the teguments
of the abdomen . The large cyft filled all the
belly : when it was raifed, the bowels ap¬
peared in a natural ftate 3 except that,
5. The left Fallopian tube was very large.
2. No ovarium of that fide could be feen
unlefs the great cyft was that ovarium im-
menfely diftended. 3. The right ovarium
was as big as the head of a new-born
child. It contained a vifcid white-co¬
loured fubftance refembling mafhed brains,
which run together like fuet when put in¬
to water. In this ftuff I found the bones
herewith fentc
The
PHYSICAL and LITERARY. 275
The bone reprefen ted in plate VI. Jig. 3.
is a piece of a jaw with three firm dentes mo -
lares r A, in it. Fzg*. 4. and 5. are two
views of a part of a jaw, in which are three
dentes molares , B, irregularly fet, and an
cifor C.
Art.
2 j6 ES S AY S AND OBSERVATIONS
ff
Art. • XIX.
Proofs of the Contiguity . of the Lungs and
pleura 3 by Alexander Monro fenior%
M. D. and P. A. ^
HE experiment of opening the thorax
JL without hurting the lungs of living
animals, while the trunks of their bodies are
immerfed in water, thro5 which no bubbles
of air rife after the perforation, as propofed
by the ingenious Lieberkuhn and executed by
the illuftrious Haller -f*, is a decifive one, if
rightly performed, for proving no air be¬
tween the pleura and lungs. But, as an un¬
wary operator may wound the lungs in per¬
forating the thorax , when air would cer¬
tainly rife in the water, from which the
exigence of air in the thorax might be con¬
cluded, $nd feveral other circurnftances
may; and have caufed the conclufion from
this experiment to be difputed 3 it may not
be arnifs to mention feme eafier ways of
proving
* February 7. 1754.
f Opufc. de refpirat
I
PHYSICAL and LITERARY. 277
proving the non-exiftence of air in this place.
Such are the following :
x. Dissect the teguments and intercoftal
mufcles from the pleura of either a dead
man or quadruped without wounding this
membrane, in which there is no difficulty ;
then pull up and deprefs alternately the fter-
num and ribs as often as you will, the lungs
ire feen contiguous all the while to the
Pleura ; but, on making a fmall pundture
thro’ this membrane, the lungs, if they are
not grown to the pleura , which is often the
cafe in the human fubje6t, fly from the
pleura , and are no more feen.
2. This connection of the lungs and
pleuray more or lefs of which is leen in mo ft
human bodies, implies ftrongly a natural
contiguity of thefe two parts.
3. Lay bare the pleura , without wound¬
ing it, between two ribs of any living quadru¬
ped, which requires no great dexterity ; and
|then the contiguity of the lungs and pleura
may be feen, tho’ the lungs are conftantly
'Hiding and changing place along the pleura ,
and tho' this membrane is in different Rates :
while the creature infpires, it is concave;
during
I
!
i
l
1
278 ESSAYS and OBSERVATIONS
during exfpiration it is convex and prominent
outwards, for this plain reafon, that while in-
fpiration is performing, the air does not pafs fo
quickly at the narrow glottis as to fill the lungs
at once with air of denfity and weight equal
to the atmofphere 3 and during exfpiration,
the air cannot efcape fo faft at the glottis as
to prevent its more than ordinary condenfa-
tion and expanfility in the lungs than the ex^
ternal air has.
If wre were to find accurately what
weight the pleura could raife when it is
made convex during exfpiration in the pre«
ceeding experiment 3 would not this deter¬
mine how much more preffure, than that of
the atmofphere, the part of the lungs within
this elevated pleura , on which this weight
is fuftained, is expofed to ?
Would not the preffure on the fame part
of the lungs during in fpi ration be nearly
as much lefs than the weight of the at-
mofphere, as is the weight raifed in exfpi¬
ration 5 fince it is the fame glottis which
allows the air to pafs in both cafes ?
Is not the force, by which the infpiratory
organs, acting with the greateft energy of
the mind, exceed the power of the exfpira~
tory .
PHYSICAL and LITERARY. 279
tory organs uninfluenced by the mind, con-
flderably lefs than the weight of the at-
mofphere \ flnce, if, after exfpiration, we
prevent the entry of the air by the glottis, we
cannot dilate the thorax as in infpiration, tho*
there is ftill a good deal of rarefying air in the
lungs ?
Do not the infpiratory organs, during
infpiration, overcome the reflftance of the
expiratory organs, and likewife that (hare of
the prefliire of the atmofphere, which the
air, rufliing into the lungs, does not ba¬
lance ?
Are not the ribs arched, and the fpaces
between them narrow, to prevent ill effects
from that unbalanced part of the atmofphere
during infpiration ?
Art.
•/<
ago ESSAYS AND OBSERVATIONS
Art. XX.
An Account of feme Experiments made with
Opium on Living and Dying Animals ;
by Robert Whytt M. D. F.R.S .
Fellow of the Royal College of Phyficians ,
and Profejfor of Medicine in the Univerfky
of Edinburgh
, r * _ ^
J v ' „ i # ' * > # •
THE ancient phyficians imagined that
opium extin guifhed the flame of life in
animals by its excefiive cold ; and ? in later
times, there have not been wanting thofe
who deduced its effects from a quite oppofite
quality, whereby it was thought to rarefy the
blood and to comprefs the brain or origin
of the nerves. Thefe falfe notions, however,
of the nature and adtion of opium , have been
refuted by feveral of the moderns, whofe
writings have thrown confiderable light
upon this fubjeft.
The following experiments were made
with a view flill further to illuflrate the man¬
ner in which this wonderful drug produces
its
* Auguft 7. 1755.
PHYSICAL and LITERARY, 28i
its effeCts, and particularly to fhew its in¬
fluence upon the motion of the heart.
1. Having injected a folution of opium
in water into the ftomach and guts of a frog,
I obferved, that in little more than half an
hour it teemed to have loft all power of
motion, as well as feeling ; for there was no
contraction produced in the mufcles of its
limbs and trunk by irritating them. I
opened the thorax an hour after the in¬
jection, and found the heart, inftead of be¬
tween 60 and 70, making only 17 pulfations
in a minute. The auricle, which was much
diftended with blood, always contracted firft,
and after it the ventricle.
2. A frog continued to move its limbs,
and leap about for above an hour after I
had cut out its heart, and was not quite
dead after two hours and a half.
• Five minutes after taking out the heart
of another frog* I injected a folution of
opium into its ftomach and guts. In left than
half an hour, it feemed to be quite dead ;
for neither pricking nor tearing its mufcles
produced any contraction in them, or any
motion in the members to which they be-
Vol. II. N n longed
28-2 ESSAYS AND OBSERVATIONS
longed. After cutting off its head, a probe
pufhed into the fpinal marrow, made its fore*
legs contrail feebly.
3. Eighteen minutes pad: four in the
afternoon, I injeiled a ftronger turbid fo-
lution of opium in water than that ufed in
the preceeding experiments into the fto-
mach and guts of a frog ; and as it fquirted
out mod: of the folution injeiled by the amts ,
I threw in fome more in its place. At
twenty four minutes pad: five, I opened this
frog, and obferved the heart with its auricle
greatly diftended with blood and beating
very flowly, not above feven times in a mi¬
nute. When the heart was touched with
the point of a pair of fciffars, its motion was
rendered quicker for two or three pulfations :
after which it became as flow as before.
4. Immediately after decollating a
frog, I deftroyed its fpinal marrow, by
pufhing a fmail probe down thro’ its fpine,
which occafioned ftrong convulfions of all
the
* V IZ' half an ounce of opium di/Tolved in eight ounces of
water ; which was alfo made ufe of in all the following ex-
penments. T he heat of the folution was nearly the lame
in all the experiments ; viz. about 60 degrees of Farenheit' 3
thermometer.
PHYSICAL and LITERARY. 283
the mufcles, efpecially thofe of the inferior
extremities. Ten minutes after this, I opened
the thorax , and found the heart beating at
the rate of 45 times in a minute. Sixteen mi¬
nutes after decollation, it moved 40 times in
a minute. After half an hour it made 36,
and after fifty minutes only 30 pulfations in
the minute, which were now alfo become
very fmall and feeble.
N. B. When I opened the thorax of
another frog immediately after decollation,
and deftroying its fpinal marrow, I obferved
its heart beating at the rate of 60 in a mi¬
nute, which is four or five pulfations lefs
than I have generally feen the hearts ot
frogs make in that time, when their thorax
was opened without decollation.
5. At nine minutes pad eleven in the
forenoon, immediately after decollating an¬
other frog, I deftroyed its fpinal marrow
with a red hot wire, which produced ter¬
rible convulfions in all the mufcles, as in
the laft experiment. I opened the thorax of
this frog thirty five minutes after decollation,
and obferved its heart beating 30 times in a
minute. The contraction of the auricle re¬
gularly preceeded that of the heart : the
auricle
284 ESSAYS and OBSERVATIONS
auricle was not near fo much diftended with
blood, nor the heart fo much fwelled as in
thofe frogs which had a folution of opium
inje&ed into their ftomach and guts % At
one o’clock (viz. an hour and fifty one mi¬
nutes after decollation), the heart of this
frog made 20 pulfations in a minute. At half
an hour paft two, when the room was be¬
come warmer by the fhining of the fun, it
beat 25 times in a minute; and when placed
in the fun beams, it performed 31 contra¬
ctions iii that time. After this, I removed
* the frog to an eaft window, where it was
expofed to a cool breeze ; upon which the
motion of its heart became flower, fo that
in a fhort time it only made 25 pulfes in a
minute* I then expofed it anew to the fun-
beams, by which its motion was foon
quickened, fo that it beat 30 times in a
minute.
At twenty five minutes p^fi: five in the
evening, (viz. Jix hours and fixteen minutes
after decollation and the deftrudtion of its
fpinal marrow) the auricle of this frog’s heart,
which was ftill filled with' blood, contracl-
ed
* See No. 3. above, and EiTay on the Vital and other
Involuntary Motions of Animals, p. 371 & 3 yz.
PHYSICAL and LITERARY. 285
ed twelve times in a minute ; but the heart
itfelf lay without motion, was fwelled and
v-ery red : however, when pricked with a
pin, it performed two or three pulfations,
and then remained at reft, till roufed by a
new Jiimulus . At thirty five minutes paft
five, the heart Teemed to be quite dead, but
the auricle continued its motion ; nay, at
half an hour paft eight, near three hours
after the heart had been without motion, the
auricle, which was very near as much filled
with blood as when I firft opened this frog,
beat 11 or 12 times in the minute ; its pul¬
fations, however, were not now fo regular
as to time, as they had been before.
Is it not probable, that the auricle of this
frog’s heart beat longer than ufual, becaufe
it continued, to the laft, to be filled with
blood 3 whereas, generally, the auricles of
frogs hearts, which are opened after decol¬
lation and the deftru&ion of their fpinal mar¬
row, expell, after fome time, the blood
which they contain, and acquire the ap¬
pearance of a fmall pellucid bladder filled
with air ?
6. I laid bare the abdominal mufcles and
thorax of a frog, by differing off the fkin,
and
286 ESSAYS and OBSERVATIONS
and at twenty minutes before nine in the
morning, I immerfed the whole body of the
frog in a turbid folution of opium in water,
in a fmail bafon, which I covered, to pre¬
vent the frog from leaping out of it. 'Thir¬
ty jive minutes after immerfion, I took it out
of the folution and opened the thorax and
pericardium . The heart’s auricle, which
was much diftended with blood, beat 15
times in a minute, but the heart itfelf, only
6 times. Forty, minutes paft nine (viz.
twenty five minutes after the frog was taken
out of the folution of opium) the heart feem-
ed to have recovered more life \ for it per¬
formed eight pulfations in a minute : the
contractions of the auricle now became
feebler, and were fcarce more numerous
than thofe of the heart, but always preceeded
them fome little time. Six minutes before
ten this heart moved only fix times in the
minute. Twenty four minutes paft ten it
made only five pulfations in fixty five feconds,
the firft, third, and fifth of which pulfations
were after an interval of fifteen feconds, and
the fecond and fourth after a paufe\of ten
feconds. Seventeen minutes before twelve,
and two hours and twenty eight minutes after the
• . frog
*
/
PHYSICAL and LITERARY* 287
frog was taken out of the folution of opium r
its heart moved only thrice in feventy five
•feconds, and performed its fyfiole very flow-
ly. Before two o’clock afternoon the heart
was quite dead ; but how long, I cannot
fay, not having had leifure to oblerve it from
a quarter before twelve to near two.
7* After cutting off a frog’s head and
defiroying its fpinal marrow with a red hot
wire, I laid bare the abdominal mufcles and
thorax , as in the laft experiment, and immer-
fed the whole body of the frog in a turbid
folution of opium , at half an hour paft nine in.
the morning, Thirty Jix minutes after im-
merfion I took it out of the folution, and
opened its thorax and pericardium. The
heart and its auricle beat, each, twenty fix
times in a minute, and the pulfations of the
auricle preceeded thofe of the heart regu-
lai Iy. The heart did not appear to be more
fwelled or redder than in a natural Rate,
and the auncie was not near fo full of blood
as in Exp. 6. Twelve minutes pall: ten, viz.
fix minutes, after this irog was taken out ot
the folution of opium , its heart beat 27 times
in a minute. At eleven o’clock it perform¬
ed 18 vibrations in that time ; and i6^t a
quarter
488 ESSAYS and OBSERVATIONS
quater before twelve. At two o’clock
afternoon, the auric.e, wh cm .uv ng c\-
air, continued its motions ; but the hca. t lav
j *
at reft. Ten minutes paft four, i. e. five
hours and forty fi minutes alter the frog
was taken out of the fbhitioni the auricle
of its heart beat o times i:i fxtv four fe-
conds.
8. I laid bare the abdcm rai mucks and
thorax of another frog, are a: rourceen mi¬
nutes part eight in the mo::' 'g, immerted
it as above in a turbic lO.rt on ct cciunu
Fourteen minutes paft r:re, I toox it out of
the folution, and lac. ere* is :ec-\:x and
pericardium ; after which the heart began to
beat at the rate of nine times in a minute 2
but the auricle, which was g ea: v entended
with blood, made no mere except in io
far as it was agitated a rtt:e ?v :re ruhauon
of the heart : nor were the muldes of the
legs or thighs brought into cc 'traction by
in a minute ;
now pretty en
of it, filled wit
hour part nine
cutting or tea
as
PHYSICAL and LITERARY. 289
as the heart. Thirteen minutes before ten,
/. e. thirty three minutes after the frog was
taken out of the folution, the auricle fhew-
ed, at confiderable intervals, a very faint
pulfation, but the heart lay without any mo^
tion.
9. The fame day, after cutting off the
head and deftroying the fpinal marrow of an¬
other frog, I laid bare its 'abdominal mufcles
and thorax ; and, at eighteen minutes part
ten, immerfed it in a folution of opium , as
above. Eighteen minutes paft eleven, I took
it out of the folution and opened its thorax
and pericardium , after which the heart began
to move at the rate of 8 times in a minute.
Twenty five minutes pad: eleven, the heart
beat 15 times in a minute.; and at twelve
o’clock it performed between 13 and 14 vi¬
brations in the fame time. At two o’clock,
(viz. two hours and forty two minutes after the
frog was taken out of the folution) the au¬
ricle, which was now filled with air, con¬
tinued to vibrate weakly, about 1 1 times in
the minute ; but the heart itfelf was without
motion. At ten minutes before four in the
afternoon, the auricle ft ill continued to
Vol. II. O o
move.
*5>© ESSAYS and OBSERVATIONS
move, but more feebly than the auricle
of N° 5-.
io. I laid open the whole abdomen of a
larger frog than any of the former ; and,
at twenty two minutes paft ten in the morn¬
ing, immerfed it in a folution of opium , as
above, thirty five minutes after immerfion,
I took it out of the folution, and opened its
thorax and pericardium . The heart was
vaftly red and much fweiled, and its auricle
greatly diftended with blood ; but both were
without any motion : after two minutes,
however, the heart began to vibrate at great
leifure, fcarcely performing nine pulfations in
a minute ; but the overftretched auricle
made not the lmalleft motion. During e-
very fiyfiole , the heart was remarkably paler,
and in the time of its relaxation became much
redder ; which phenomenon I obferved like-
ways in all the frogs hearts in the above ex¬
periments, but more remarkably in thofe
frogs who had been expofed to the addon
of opium . Another thing, which I remark¬
ed in all thefe experiments, was, that the
heart, during its fiyfiole, became manifestly
Shorter, and was lengthened in the time of
its relaxation. But to return *, at fix minutes
paft
PHYSICAL and LITERARY.
291
paft twelve, (i. e. an hour and nine minutes
after the frog was taken out of the folution)
its heart made only 6 puliation s in the mi¬
nute ; and at eleven minutes paft twelve,
oblerving it without motion, I pricked it
with a pin, and breathed upon it, in order to
renew its pulfation, but to no purpofe.
1 1. Twenty eight minutes paft feven in
the evening, I laid open the whole abdomen
and thorax of a frog, and immediately after
immerfed it in a folution of opium as above.
Thirty eight minutes paft feven, when I prick¬
ed its legs with the point of a penknife, it
made very little motion. Two minutes after
this, I turned it to its back, and obferved its
heart moving only between ten and eleven
times in a minute. Having laid the frog a-
gain on its belly, that it might be more ex-
pofed to the adlion of the opium ; at forty
*
eight minutes paft feven, i. e. twenty minutes
from the firft immerlion, I turned it again
to its back, and obferving the heart without
motion, I opened the pericardium ; which
producing no effebt, I cut the heart out of
the body, and laid it on a plate, when it
gave two or three pulfes, and never after
moved,
t9i ESSAYS AND OBSERVATIONS
moved, tho’ it was pricked once and again
with a pin.
No motion was produced in any of the
other mufcles of thi§ frog, by irritating
them.
12. I cut off a frog’s head and deftroyed
the fpina! marrow with a hot wire, then laid
open its thorax and abdomen , and immerfed
it in a foliation of opium at nineteen minutes
pail eleven. Eight minutes before twelve,
i. e, thirty three minutes, after immerfion, I
obferved its heart beating very flowly : but
two minutes before twelve, when I took it
out of the folution of opium , it had no mo¬
tion. After, this I opened the pericardium ,
and irritated the heart two or three times
with the point of a fcalpel , which always
produced a few pulfations. I then put the
frog in the folution for five minutes more,
and, upon taking it out, found its heart quite
dead,
13, After cutting off a frogs head and
deilroying its fpinal marrow, I laid open its
whole abdomen , and immerfed it in a folution
of opium, twenty three minutes before one.
After it had lain Jixteen minutes , I cut up its
thorax and pericardium 5 and obferving the
heart
PHYSICAL and LITERARY. 293
heart beating very regularly and pretty
ftrongly, 21 times in the minute, I immerfed
it again in the folution, which had now im¬
mediate accefs to the heart. After five mi¬
nutes, I took it out of the folution ; and
finding the heart without motion, I pricked
it with the point of a knife ; upon which it
began to beat at the rate of 14 times in the
minute, and .continued its motions very
languidly, and not without fome interruption,
for about a quarter of an hour. r
14. I cut out the heart of a frog, and put
it in fountain-water at ten minutes paft ten
immediately after immerfion, it beat about
28 times in the minute. Eighteen minutes
paft ten, it made 6 pulfations in thirty fe-
-conds. Twenty minutes after ten, I took it
out of the water and laid it on arable, and
obferved, that as often as it was gently
touched with any thing, it made one full
and ftrong contraction, and no more :
however, in four or five minutes, it be¬
gan to beat of its own accord, and, at
twenty eight minutes after ten, performed
19 pulfations in a minute. Thirty five mi-
minutes paft ten, it beat 12 times in a mi¬
nute,
15. Twenty
294 ESSAYS and OBSERVATIONS
15. Twenty three minutes part twelve*
I cut out the heart of another frog, and put
it in fountain-water. After twelve minutes,
immerfion, I took it out of the water, when
it beat above 20 times in a minute. Having
put it in the water for five minutes more*
it ceafed from motion, and when taken out,
did not move except when pricked, and then
only performed one pulfation.
16. Eight minutes pad: eleven, I cut
out the heart of a third frog, and put it into
fountain-water. Eleven minutes after im¬
merfion its heart beat 8 times in the mi¬
nute, and four minutes after this it vibrated
jj times in thirty feconds \ but the motion
was confined to about one third part of the
heart next its apex . Twenty minutes after
immerfion, it continued to move much in
the fame way 5 but in two minutes more,
obferving no motion in it, I took it out of
the water, and laid it on a table, where it
remained at reft, unlefs when touched. Soon
after this, however, it began to move ; and
at twenty five minutes after immerfion, it
made 9 pulfes in fixty three feconds. Four
minutes after this, it moved only thrice in
fifty feconds? and then ceafed altogether ;
unlefs
PHYSICAL and LITERARY. 295
#
unlefs that, when pricked with the point of
a knife, it gave one very faint pulfation. At
forty feven minutes paft eleven, it was quite
dead.
17. I cut out the heart of a fourth frog,
and at thirty minutes paft ten immerfed it in
a turbid folution of opium in water of the
fame degree of heat with the fountain- water
ufed in the three laft experiments After
this heart had been immerfed ten minutes ,
I took it out of the folution, and laid it on a
table, but it made not the fmalleft motion ;
and when pricked with the point of a knife,
tho’ it quickly recovered its fhape, yet it was
not excited into a proper contraction, as the
heart of N° 14. I continued to obferve this
heart from time to time for more than half
an hour, but it never made the leaft motion.
18. I cut out the heart of a fifth frog, and
put it into a folution of opium in water
five minutes before eight. After feven mi¬
nutes immerfion, I took it out, and laid it
on a plate, where it remained at reft. When
pricked with a knife, it did not perform a
full pulfation like N° 14. but feemed to feel
a
* Nearly fixty degrees of Farenheit's thermometer.
196 ESSAYS and OBSERVATIONS
a little, by a very faint kind of motion which
was excited in feme of its fibres.
19. At thirteen minutes before twelve, I
cut out the heart of a fixth frog, and immer-
fed it in a folution of opium. Six minutes
after immerfion, it had no motion ; but
when pricked, made one pulfation. After
lying five minutes more in the folution, it
was quite dead.
20. I cut out the heart of a feventh frog,
and at thirty feven minutes paft nine in the
morning, immerfed it in a folution of opium ,
as above. Forty two minutes after nine,
when I took it out of the folution, it was
without motion : but when touched with
the point of a knife or probe, it performed
one contraction, but with lefs vigour and
more flowly than the heart of N° 14.
Forty feven minutes paft nine, it began to
beat of its own accord. Two minutes after
this, it moved 6 times in the minute, but
much more feebly than N° 14. Six minutes
before ten, it beat only 4 times in a minute :
after this, it began to beat much fafter ; but
its motions foon returned to their former
flown efs. At ten, after having lain near a
minute without motion, it began again, of
its
PHYSICAL and LITERARY. 29f
its own accord, to beat at the rate of
37 times in the minute, and continued for
eight or ten minutes after this to beat very
feebly, and in an irregular manner as to
time.
21. Mr. Robert Ramfay Student of medicine
in this place, having diffolved two fcruples
of opium in an ounce of water and a dram of
liquid laudanum , injedted it blood-warm into
the inteflinum redlum of a very fmall dog near
fix months old. In lefs than a minute after
the injeftion was made, the dog could not
ftand on his hinder legs ; and in 3 or 4 mi¬
nutes he had loft the ufe of them fo much,
that when they were ftrongly pinched, he
neither moved them, nor feemed in the leaft
degree' fenfible of pain. He could, however,
ftill fcramble about with his fore-legs ; and
when they or his ears were pinched, he
howled remarkably, and feemed to feel con-
fiderable pain. Ten minutes after the inje¬
ction, he lay as if he had been quite ftupid ;
only when a noife was made by beating on
the ground, he opened his eyes a little and
howled, but prefently after fell into a pro¬
found fleep. In a few minutes after this,
he began to be convulfed ; upon which Mr.
Vol. II. P p Ramfay
29S ESSAYS and OBSERVATIONS
Ramfay injected a ftrong folution of fea fait
in water into his guts, which purged him fe-
verely, and occafioned a prolapfus ani ; foon
after this, he awaked from his fleep, and
gradually recovered the ufe of his hinder legs^
fc that in lefs than an hour he could run a-
bout the room, tho’ he often fell down,
his legs bending under him. After three
or four hours, he feemed to be quite well
in every refped ; but altho’ the experiment
was made at mid-day, he could tafte no meat
till late at night. When he was in the moft
ftupid Rate, he could make ufe of his fore¬
legs, and complained when his ears were
pinched,
22. The fame young Gentleman, at my
defire, made the following experiment.
On the 9th of April 1755, after making an
opening into the cavity of the abdomen of the
dog on whom the laft experiment was made,
he injeded by the wound a dram of opium
diflblved in two ounces and a half of water 5
but before he could flitch up the wound,
about an ounce of the folution efcaped. The
dog loft the power of his hinder limbs al-
mod inftantaneoufly. Two minutes after the
injedion was made, he began to beconvul-
PHYSICAL and LITERARY. 299.
fed 5 and, in two minutes more, after ha¬
ving raifed himfelf upon his fore-legs, he fell
down fenfelefs. At this time Mr. Ra?nfay laid
bare the thorax , by directing off the tegu¬
ments, which did not feem to give the dog
any pain, and could plainly feel the motion
of his heart thro5 the pleura : it beat 76 times
in a minute, but became gradually flower
Immediately after counting the pulfe, Mr.
Ramfay cut the ribs on each fide of the Jler -
num , which he laid back in the ufual way.
The heart, which was thus brought in view,
appeared quite turgid, and continued in mo¬
tion about five minutes ; during which time
it performed only between 60 and 65 weak
vibrations, for they were not compleat con¬
tractions. While the heart was thus moving,
warm faliva was firft applied to it, then cold
water, and laft of all oil of vitriol 5 which
fhrivelled the parts it touched, almoft in the
fame manner as a hot iron would have done >
but none of them accelerated the heart’s vi¬
brations, which became gradually flower, till
they ceafed altogether.
The
* The dog’s heart in a natural date, and before the in*
iedtion of the folution of opiuwt beat 1 50 in the minute.
300 ESSAYS AND OBSERVATIONS
vJ - -
The fibres of fome of the intercoftal mufcles
< ' ^
on the right fide of th t jlernum continued to be
agitated with a weak tremulous motion near
half an hour after the injedion was made
into the abdomen ; but the intercoftal muf-
cles attached to the ribs on the fides of the
* - . J l X *■- • . *. A A m , . .
thorax were not obferved to move, nor
. / . ►. ^ S i ' *• •- : - "• • * '
did the diaphragm make any motion when
its fibres were pricked or cut.
Nothing remarkable was feen in the ab~
domen ; only, altho? it was opened ten mi-
notes after making the injedion, the inte-
ftines had no motion : whereas, in another
young dog, which had got no opium , Mr.
Ramfay obferved the periftaltic motion conti¬
nue half an hour after laying open the thorax .
The dog loft little or no blood in making
the wound into his abdomen , nor were any
c ’ '' ' ' ' v. '
of h is bowels hurt by it.
23, A final 1 dog into whofe ftomach the
late celebrated Dr. Mead had forced, at four
different times, a folution of two drams of 0-
pium in water, lived above an hour and three
quarters after getting the firft dofe. Vida
treat ife on poifo?iSy Effay IV.
24. It may not be improper to add here
an experiment related by Dr. AIJion in his
leranecj
PHYSICAL and LITERARY." 30*
learned differtation on opium Into the
crural vein of an old dog forty two pounds
weight, he caufedbe injedted at three different
times, half an ounce of opium diffolved in
four ounces of water, filtrated, and of the
fame warmth with the blood of the animal.
The firft time, about fifteen drams were
thrdwn in, and very flowly. It had no obfer-
vable effedt. About an hour after, eight drams
more were injedled flowly, and immediately
the dog was feized with ftrong convulfions ;
the pulfe was frequent and fmall, and after
fome time he foamed at the mouth. But
there appearing no figns of immediate death,
after waiting an hour more, the laft nine
drams were thrown in quickly 3 upon which
the pulfe became full and flow, and in a mir
nute or fo, the dog expired.
From the proceeding experiments, we
may, I think, fairly draw the following con-
clufions.
(a) Opium applied to the ftomach, guts,
cavity of the abdomen and thorax and abdo¬
minal mufcles, foon leffens, and after fome
time intirely deftroys all feeling and power
• • - - * : ; of
* Edinburgh Med. Effays, vol. v. p. i. art. xii9
302 ESSAYS AND OBSERVATIONS
of motion, not only in the parts to which
it is 'applied, but thro" the whole body.
N° i, 2, 3, 8, 11 & 22.
(b) Opium produces thefe effeds much
more quickly in animals which are foon killed
by want of food and air, than in thofe which
can live long without them, and the parts of
whofe bodies preferve a power of motion
and appearances of life for a confiderable
time after they are feparated from each
other. N° i, 3, &c. compared with N°2i,
22 & 23.
(c) Since a foiution of opium injeded into
the ftomach and guts deftroys the fenfibility
and moving power of frogs, fully as foon
when they are deprived of their heart, as when
this organ remains untouched; it follows,
that opium applied to thefe parts, does not
produce its efFeds by entering the blood, and
being, by its means, conveyed to the brain,
as feme have imagined, but by its imme¬
diate adion on the organs and parts which
it touches. N° 1. compared with N° 2.
See alfo Edinburgh Medical EJfays , edit. 3.
vol. 5. part 1. page 140.
(d) Since, after decollation and the de~
ftrudion of the fpinal marrow, opium ope¬
rates
PHYSICAL and LITERARY. $oS
rates much more flowly in deftroying the
heart’s motion in frogs, than it does when
the animals are intire (N° 6. compared with
N° 7.) ; it follows, that it muft produce its
eflfeds chiefly, if not wholly, by its adion on
the brain, lpinal marrow, and nervous fyftem.
The heart of the frog N° 7. whofe brain
and fpinal marrow had been deftroyed, beat
27 times in a minute, after the animal had
lain thirty flx minutes in a folution of opium \
which was only three pulfations lefs than the
heart of the frog N° 5. performed thirty five
minutes after the deftrudion of its brain and
fpinal marrow, altho’ it was not expofed to
the adion of opium .
(e) When opium injeded into the veins,
and thus mixed with the blood, leflens or
deflroys the fenfibility and moving power of
animals much in the fame way as when it
is applied to their ftomach, guts, or cavity
of the abdomen (N° 24) •, is it not probable,
that it produces thefe effeds by its adion on
the extremities of the nerves which termi¬
nate upon the internal furface of the heart
and whole vafcular fyfliem ; and perhaps,
alfo, by affeding immediately the medulla
cerebri itfelf ? And when a folution of opium
applied
§04 ESSAYS and OBSERVATIONS
applied to the bare abdominal mufeles of a
frog deprived of its brain and fpinal marrow,
does, after a long time, confiderably impair
* / T / '
the heart’s motion ; is it not reaforiable to
think, that this is owing to the finer parts
of the opium being abforbed by the bibulous
veins and carried to the heart, and thus
brought into contadf with the nerves of this
organ ? N° 7. compared with N° 9.
» » ■ * ' *** • - »
c (fj Since opium, without entering the
«. t, .
blood or being carried to the feveral parts of
the body, deftroys the power of feeling in
animals merely by adting on the nerves to
which it is applied (e) (d), it follows, that
the nerves are the inftruments of fenfa-
» * «
tion, or, at leaft, neceffary to it. Nor is it
r
fufficient to deftroy this conclufion, that
there have been inftances of animals endow¬
ed with feeling whofe brains were fo greatly
difeafed, as to feem incapable of performing
their fundlions. It is far from being fafe to
* i
build theories in phyfic upon a few mon-
ftrous appearances in nature;
(g) It appears from N° 4. and 5. com¬
pared with N° 3, 6, 8, 10 and 11. that de¬
collation and the deftrudtion of the fpinal
marrow does not weaken or deftroy the
heart’s
PHYSICAL and LITERARY. go£
b
heart's motion in frogs, near fo fopn as opium
injedted into their ftofnach and guts, or ap¬
plied to the mufcles and bowels of the lotver
belly and thorax . r.o . lt-
(h) Althg’ a folution bf opium applied
to the Opened thorax and abdomen of a frog9
after decollation and the deftrudtion bf its
fpinal marrow, foon weakens or deftroys the
■x «, # *•-
motion of the heart ; yet it does not pro¬
duce thefe effedts fo fpeedily as when the
brain and fpinal marrow are intire, N9 if,
and 12. In the former cafe, the opium can
•* * r
only affedt the heart by its topical influence*
in the latter, it not only adts this way, but
alfo exerts its powers upon the brain, fpi¬
nal marrow, and whole nervous fyftem *
and therefore inuft produce more fudden
feffedfs.
[i ) It appears, beyond doubt, from the
preceeding experiments, that the heart is not
, .... .• * 9 * * f
exempted from the power of opiums as the
learned Dr. Haller has affirmed *, but has
its motion deftroyed by it, as well as the o~
ther mufcles, only not fo foon. See N° 4,
and 5. compared with N° 3. 6. 8. & io,
Vol. II. Q_q and
* An. Getting, vol. ii. p, 147 & 154-
fg& ESSAYS AHr0 -GB S ER VATIC) NS
«/
^and N°f 14. 15. & 16. compared with
¥7.^8. 19V & 20.
^Tia true, that the fibres of the intercom
Hals on the right fide of th t fiernum of the
dog N° 22. continued to be agitated with a
tremulous motion confiderably longer than
the heart, . and when the intercoftal mufcles
attached to the ribs were quite dead. But
did not this happen becaufe, after feparating
the [iernum from the ribs, and thus cutting
off all communication; between it and the
fpinal marrow, the mufcles attached to it,
could be no more -affeded by the opium ,
which had been dnjeded into the cavity of
the abdomen while the heart and other muf-
A . A J J ’ <»■ C— •* W- > •» *■
cles whofe communication, by means of the
nerves, with the brain and fpinal marrow,
was intire, continued to be expofecbto -its
adion "q
~ r x i
* As Dr. Langrijh lias obferved, that
the diftilled water of laurel-leaves injeded in¬
to the cavity of the abdomen^ hills dogs fooner
than when it is taken into the ftomach * $
foN°2i.and 23. compared with N° 22.
ihew that opium injeded into the ftomach and
0 O X:. . great
# Phyfical experiments on brutes, p. 64.
P H Y S I C A L an d LI T ERA R Yrr joj-
great guts of dogs, does not produce either
fuch fpeedy or powerful effeds, as .when
thro wn into the cavity of the abdomfn* ; Ajk|
N° 6. compared with NQ io. fhews, that a
folution of opium applied to the abdominal
mufcles,' does not kill frogs fo foon as. when
all the vifeera of the lower belly are expofed
to its adion.
(l) Altho’ it feems probable, from N° 22.
compared with N° 24. that a folution of 0 -
injeded into the veins of dogs does not
kill them fo foon as when thrown into the
v •' - .• 1 - y
• M 1 - * ' * ■ * ‘ ^ #<i •- ‘ • “ 4<
cavity of the aodomen fyet this cannot be cer-
, ’ _ - ■ ■' ' J <w v...
tainly concluded, fince the dog of N° 24.
L,‘ •' *• • • * - '
was much older and above ten times, heavier
. ; , •, . > ’ f- '■ i ' • *•' ' i
than the other.
(m) It appears, that a folution of opium
injeded into the great guts of a dog, affeds
the inferior part of the fpinal marrow much
more remarkably than its fuperior part, or
the brain $ fince the dogs of N° 21. and £2,
not only loft the power of motion fooner in
their hinder legs than in their fore ones, but
alfo were infenfible of any pain in them, and
yet howl’d ftrongly when their ears were
pinched.
(11) A‘
3*B ESSAYS and OBSERVATIONS
(;z) A folution of opium injeded into the
cavity of the abdomen or great guts of dogs,
does not deftroy the feeling and power of
motion of their hinder limbs, by fending
any effluvia to their mufcles otherways it
could not produce thefe effeds fq inftantane-
oufly, (N° 21. & 22.) Befides, fince opium
thrown into the ftomach and guts of a frog
after being deprived of its heart, deftroys
the fenfibility and moving power of its muf¬
cles equally foon, as if the animal had been
intire (N° 2.) $ ’tis plain, that thefe ef¬
feds cannot he owing to the finer parts of
the opium being received into the blood, and
by its means carried to the feveral mufcles
and organs.
(0) Nor does a folution of opium injeded
into the great guts or cavity of the abdomen
in dogs produce its effeds by tranfmitting
through the nerves any fubtile effluvia to the
fpinal marrow 5 otherways its operation could
not have been fo inftantaneous (N° 21.
& 22.) ; nor could the fpinal marrow and
its nerves have recovered their fundions fp
foon, after the opium was evacuated by a
purgative clyfter, N° 21.
(AJlT
x
PHYSICAL and LITERARY. 309
(p ) It remains, therefore, that opium > by
affecting the extremities of the nerves of the
parts to which it is applied, does, by means
of their connexion and fympathy with the
brain and fpinal marrow, deftroy or prevent,
through the whole nervous fyftem, the o-
peration of that power upon which depends
fenfation and motion in the bodies of ani¬
mals.
(q) Since opium applied to the abdomi¬
nal mufcles of a frog, deprived of its brain
and fpinal marrow, does not deftroy the mo¬
tion of the heart fo foon, as when it is ap¬
plied to the abdominal mufcles of a frog
whofe brain and fpinal marrow are intire,
(N° 6. and 7.), it follows, that the brain and
fpinal marrow, and confequently the nerves
derived from them, have a greater influence
than any other part of the animal fyftem,
upon the motion of the heart
(r) Opium does not only deftroy the
moving power of the mufcles of animals by
intercepting the influence of the brain and
fpinal marrow, but alfo by unfitting the
mufcular fibres themfelves, or the nervous
power lodged in them for performing its of¬
fice : otherways a folution of opium, when
**o ESSAYS AND OBSERVATIONS
applied to the abdominal mufcles or vifcera
of a frog, would not put a flop to the heart's
motion fooner, or indeed fo foon, as decol¬
lation and the deftrudtion of its fpinal mar-
row, (N° 4. & 5. compared with N° 8.
& ip,). Opium therefore does not produce
its effedts, Jolely , by putting a Hop to the
fundtipn of the brain and fpinal marrow,
but its influence reaches to the fibres of the
mufcles themfelves,' or to the extremities
of the nervous filaments which terminate in
them.
v t ■ if '
When I fav the influence of opium reaches
to the nervous filaments which terminate in
r - .v •> • J * *>-- .. ; . 4..-V * -*> • * <
the mufcular fibres, it is not meant, that
any effluvia or fubtile parts of the opium are
transmitted to them (See n fflc 0 above),
but that it deftroys their powers, by means
of that fympathy which they have, through
the brain or fpinal marrow, with the nerve^
to which the opium is immediately ap~
(J ) From the above experiments we may
infer, that not only the power of voluntary
motion in the mufcles, but alfo their irrita -
<* *
bility or power of motion, when flimulated,
proceeds from the nerves, or is at leaftim-
’ , „ mediately
■ix .. „ . •• ' ^ v)
I PHYSICAL and LITERARY- g**
AnecUately dependent on ' their influence ;
:fince opium] which produces its effects, fold%
~by' affecting the nervous fyftem ( m; n &
dj, deftroys thofe powers fo fudderily.
I know, it has been lately argued by a cele-
• . * •• v f
t rated authdr, c that the -irritability of ; the
mufcles muft be independent of the nerves,
becaufe the mufdes of animals preferve a
power of moving when irritated, for fome
time after the communication between them
sind the brain,- by means of the nerves, is cut
off But firce a folution of opium applied
to the abdominal rhufcles of frogs, ’ merely
-by its action on the nerv^sy puts a flop to
the irritability’ of moving power of the heart,
& - $ « %
much fooner than the deftruft'ion of the brain
« < ^ * *S * ‘*\ •* f * .
and fbinal; marrow £g~) 5 is it not reafenable
to conclude, that the tremulous motions of
irritated mufcles after their f nerves, are I tjed,
proceed from the integrity of the nervous
filaments below the ligature, and the mer—
' vows power ftill remaining in them or in the
mufcula'r fibres themfelvesf ’• *
The tying or cutting of a nerve, ''only
prevents the derivation of any new influerree
*'-■> ' >** b<r‘* r - -vr>.
AOa Gotting, vol, ii. p. 134, &c. .
TA $
3*2 ESSAYS AND OBSERVATIONS
from the brain, to the parts to which it be¬
longs y but does not immediately deftroy the
power or influence remaining in the nerve it-
felf. Opium applied in fufficient quantity to
the fenfible parts of animals, not only quick¬
ly puts a flop to the function of the brain
and fpinal marrow, and thus produces in the
mufcles all the effedts of a ligature on their
nerves, but alfo deftroys th z power of every
nervous filament in the body (r), and there¬
fore puts a flop to the motion of the heart
in frogs fooner than the deftrudtion of the
brain and fpinal marrow*
(t ) The almoft inftantaneous palfy brought
on the hinder legs of a dog, by injedting a fo-
lution of opium into the cavity of its abdomen
(N° 22*), arid the effedts of the fame folution
injedted into the ftomach and guts of a frog
deprived of its heart (N° 2*), where no part
of the opium could be conveyed to the muf¬
cles, nor be conceived to alter the nature
of their gluten ; {hew, that the irritability
of the mufcles has not its feat in this glue , as
fome have lately imagined*. But if the
motions of irritated mufcles be owing to a
difagreeable fenfation excited in them or
their
* Gotting. vol. ii. p. 152.
PHYSICAL and LITERARY. 313
their nerves, as we have elfewhere endea-
l
voured to (hew ’tis eafy to fee that opium
muft, by deftroying the fenfibility of the
mufcles, of confequence alfo deftroy their
irritability *
(u) In animals which have got a large
dofe of opium , the veins, efpecially thofe of
the membranes of the brain, are obferved
to be much fwelled ; whence it has been
thought, that opium produces its effeds in
the bodies of animals, partly, at leaft, by
rarefying the blood and compreffing the
brain : but this diftenfion of the veins feems
to be no more than a confequence of the ve^
ry flow motion of the blood through the
heart, on account of the infenflbility with
which this organ is affeded *f*.
(v) Since opium foon puts a flop to the
vital motions of animals, which yet continue
Vol. II. R r , in
* Effay on the vital and other involuntary motions of a-
nimals, fed* ix* and Phyfiological Eflays, p. i88, &c.
-f- In frogs, into whofe ftomach and guts I had injected
a folution of opium , I not only found the heart’s auricle,
but alfo the great veins leading to it, much diftended with
blood. Vid. EfTay on vital motions, &c. p. 371. and
372-
ESSAYS and OBSERVATIONS
3H
in time of deep with little or no diminution
of their vigour 5 fince it often eafes pain
Without bringing on deep, and fince, by its
topical aftion on the heart, it deftroys the
motion of this organ after all communication
t* * r ? * m
between it and the origin of the nerves is
cut off* ; it follows, that the effe&s of opium
are not owing, as fome have thought, to its
producing deep : on the contrary, the deep
which it occadons, feems to be only a con-
fequence of its impairing the fendbility of the
whole nervous fydem.
The other effects of opium may be alfo de¬
duced from the fame caufe, particularly its
reftraining all evacuations that are owing to
an unufual irritation of the parts of the bo¬
dy, and at the fame time promoting thofe
natural fecretions which have been diminifh-
ed or ftopt by fpafmodic ftridtures of the vef-
fels, from fome uncommon Jiimulus. affecting
them.
(w) Lastly, does not opium kill animals
by rendering their feveral organs wholly in-
fendble of the Jiimuli , which are deftined
by nature to excite them into adtion ; whence
not
* Vid. N° 12. 13. 17. iS. 19, & 20. above.
PHYSICAL and LI TEH ARY. I 3^1 5-
pot only a flop is put to the perlftaltic imo-.
tion of the guts, and to the propulfion of
the chyle but the fluids alfo begin to
ftagnate firft in the fmaller and afterwards
in the larger veflels -f* 5 while the heart be¬
coming gradually lefs fenfible of the Jlimu -
lus
* . * ♦
* ' •’<* * ' • '> •' • a •* ^ ** -s
' “ . • " “ '
* In a fmall dog, which Dr. Kami Boerhaave ppened;
after having given him three grains of opium , he obfer¬
ved fcarce any periftaltic motion in the guts: the fto-
rnach was much diftended ; the pylorus was fhut, and the
*
bread and milk, which the dog had taken with the opium
about ten hours before, was indigefted. There was no¬
thing like chyle in the duodenum , nor any ladleal veflels
to be feen in the mefentery. The bladder or urine and
great guts were much filled, nor had the animal eva¬
cuated either urine or faces from the time he fwallowed
the opium „ Impetum faciens Hippocrati difitum, p. 402. & 403.
The learned Dr. Haller has alfo obferved, that opium
puts a flop to the periftaltic motion of the guts in frogs
and other animals, A 61. Gotting. voh ii. p. 154.
*f- This my worthy Collegue Dr. Aljlon obferved with a
microfcope in frogs into vvhofe ftomach he had conveyed
a few drops of a folution of opium in water. Fid. Me¬
dical Eflays, vol. v. part 1. art. xii. And indeed the
great diftenfion of the heart and its auricle in frogs kill¬
ed with opium (N° 5. compared withN° 3. 6. & 10. above)
indicates a more than ordinary refinance to the blood's
motion in the arteries, as well as a lefs degree of irrita¬
bility in the heart. Further, is not the flow, full pulfe,
and dry parched mouth in thofe who have got an over-
dofe
ji 6 ESSAYS and OBSERVATIONS
Jus of the blood with which it is diftended,
contracts more feebly and at greater intervals,
till at laft it ceafes from motion altogether ?
Art.
. - . j . . , , ^ i
dofe of opium, owing, partly tp the flower motion of the
•fluids in the fmall arteries^and fecretory veflels of the glands ?
Tho’ it muft be confefled, that the drynefs of the mouth
jnay be in fome meafure owing to the perfpiration being
greatly increafed by thp opium.
PHYSICAL and LITERARY. 3i7
Art. XXL
■ The Hiflory of a compleat Luxation of the
Lhigh , in a Letter to Dr . John Ruther-
foord, P ref dent of the Royal College of
Phyficiam , and Prof e for of Medicme in the
JJmverfity of Edinburgh ; by James Mac¬
kenzie, M. D . late Phyfician at Wor-
cefter
SIR ,
Feb. io. 1755.
^E account which I gave you of a
u X compleat luxation of the thigh re-
duced at the Worcefler Infirmary, I now
cc fend in writing, agreeably to your requePc.
u I fend you alfo Dodtor Walls Letter vouch-
cc ing this difiocation 5 and Mr. fefferys s
<c narrative of the fame cafe. If you think
£C any further proof neceffary, there are ftill
£c two Phyficians and tv/o Surgeons more,
alive and well, who were prefent at the
<c reduction, and will bear witnefs (if requi-
u red) to the truth of this accident, as well
<c as the two Gentlemen above named, and
“ myfelf, who am, &c.”
William
f March 5. 1755.
3 1 B ESSAYS and OBSERVATION'S
WIlliam Jones, a tall, robuft, heal¬
thy Butcher, fifty fix years old, was
carried to the Worcejler Infirmary on the
feventeenth of Augujl 1747, lame, and in
grievous pain. His account of himfelf was,
That he happened unfortunately, fome hours
before, to ride an unruly horfe, which ran
away with him ; and that, making an ef¬
fort to check him, juft as he was galloping
over a ftone bridge, the animal reared himfelf
upon his hinder feet 3 and immediately fell
backward on his rider. The man was ftun-
ned with the fall ; but. the horfe quickly re¬
covered himfelf, and went off full fpeed,
dragging poor Jones after him, by his leg
which was engaged in the ftirrup. The
horfe was foon providentially flopped, and
the man fet at liberty, but unable to move
his thigh, which he believed was broken.
The Surgeon in waiting, (for four Ph.yfi-
cians and three Surgeons gave their atten¬
dance in rotation, namely, Doctors Attwood \
Mackenzie , Cameron , and Wall ; and Meff.
Edwards, Ruffe! , and Jeffery s ) having tho¬
roughly examined the fituation and figure of
the-
PHYSICAL and LITERARY* 319
the parts difabled and in pain, came to one
of the Phyficians, and told him, that the
poor man’s thigh was diflocated ; that the
head of the bone was ftruck quite out of
the acetabulum , and lay fairly in the groin.
The Phyfician having, in his younger days,
attended Boer haave (who, furely, underftood
phyfic and furgery as well as any man ever
did), and knowing that, from the prodigious
firength of the ligaments, and depth of the
focket in that articulation, this learned Profef-
for was of opinion, that the thigh-bone was
never diflocated by external violence, but fre¬
quently broken near the head : which was the
true reafon why fuch accidents were feldom,
or never, cured : the Phyfician, I fay, perfua-
ded, that his preceptor was in the right,
obferved to the Surgeon, that there muft be
a miftake fomewhere, and that there was no
inftance on record, which could be depend¬
ed upon, of fuch a luxation as he defcribed :
to which the Surgeon replied, cc Sir, if you
Cf will not believe me, you will believe your
<c own eyes and fingers prefently.”
The novelty of the cafe brought all the
Phyficians and Surgeons to the Infirmary.
A Skeleton was fetched, and great care ta¬
ken
£20 ESSAYS and OBSERVATIONS
ken, by a Arid inquiry into circumftances,
to fatisfy all prefent, that the bone was not
broken, but really and fairly diflocated.
There is no reafoning againft fads : the
toes and knee were turned outwards, the
difabled limb was longer than the found,
the hip-joint utterly inflexible, and the round
large head of the bone lay obvious to the
fight and touch in the groin.
The next inquiry was, how this difloca-
tion fhould be reduced. All were called to
confultation ; not one of the Phyficians or
Surgeons had ever feen the cafe before.
Some of the principal books of modern fur*
gery were looked into ; but one and all de*
fcribed the reduction, and recommended
extenfion in fuch a general, languid, hear-
fay, manner, that it was plain they were as
unpradifed in the cafe, as the Gentlemen
prefent : nor was any better fuccefs to be
expeded from Galen s ® method of reducing
a
* Vid. Gal. in librum Hipp. de artic. commentarior.
lib. 4. aph. 42.
And indeed the antients feem to have been acquainted
with luxations of the hip-joint only in children, or di (tem¬
pered bodies ; unlefs we (hall except Paulus JEgineta,
vvhofe
PHYSICAL and LITERARY. 321
& luxation of this joint by hanging the pa¬
tient to a ftrortg beam by the heels with his
head near the ground.
After mature deliberation, it was agreed,
that, in cafe the ufiial extenfion did not fuc-
ceed, the vis pert ujfionis (which is well known
to increafe the force to a furprifing degree
by accelerating the motion) fhould next be
tried. In order to both, therefore, we nrovi-
ded a large ftrdng table, of a proper length
and height, which we faftened with fcrews
V , f- ■ , »
to the floor, and covered with fuch blankets
and bolfters as we wanted; a piece of ftrong
cloth alfo was laid upon the blankets, un¬
der the patient’s back, of length fuffipient
to turn up between his thighs, and pafs over
his fhoulders down to the floor, where both
ends were fecurely fixed; With a view td
refift or counteract the neceflfary extenfion.
We provided alfo two towels of a conve¬
nient length and thicknefs ; one of which5
at the middle, was tied with a tight, but
eafy knot above the patient’s ankle, and the
two ends twilled together, were given to three
Vol. II. S f ftrong
a
whofe various methods of extenfion, in this cafe, whether
real or fuppofed, feme of the moderns have copied, and
fome have altered.
sfi2 ESSAYS a^d OBSERVATIONS
ttrong men to hold. The other towel was
in the fame manner fattened above the knee,
and the double end given to three more ^
while the Surgeons ttood ready, one with
his hand on the ball of the diflocated bone
to diredt it into the focket, one at the knee,
and another at the foot to turn them inwards*
•» ,
When all things were ready, the exten-
fion was begun, in the common method,
by the towel-men ; but tho’ they exerted
their utmoft ttrength, the head of the bone
was not moved in the leatt, and their effort
ferved only to increafe the poor man's tor¬
ture to an intolerable degree.
Finding thus the extenfion of no figni-
ficancy $ and the patient’s courage reviving
after fome refpite y the vis percujjionis was
was carried into execution after the follow-*
ing manner. The towel-men were diredted
to flacken their towels to a certain point, to
Hand with their feet firm, their arms {freight,
and their bodies bending a little forward 5
and, upon a certain fignal agreed on, were
ordered to pull with a vehement and quick
jerk, throwing themfelves back with all their
might.
Afteb
PHYSICAL and LITERARY. 323
After every thing was in good order,
:nnd the afiiftants apprifed of the nature and
neceflity of the operation which they were
about to perform 5 the fignal agreed on was
at daft given. The towel-men pulled in a
moment with a ftrong and fudden fpring ;
the Surgeons performed their parts dexte-
rouily ; and inftantly there was a loud crafh
heard, which made one of the Phyficians
callout, Alas! the table is broken. But
at that very moment the patient, with a
thundering voice, cried, It’s in, it’s in, it's
in. And fo it really was 5 for we imme¬
diately found the limb reftored to its natural
pofition, length, and flexibility. The pa¬
tient was put to bed ; and, by a proper diet
and care, recovered his former health, and
could walk perfectly well in three weeks.
One of the Phyficians often met him after¬
wards on foot driving cattle, and always
afked, How he did ? To which his con-
ftant anfwer was, Very well, thank God and
the Gentlemen. And he can now, upon oc-
cafion, walk twenty miles in. a day, without
fatigue or pain, tho5 the injured limb ft ill re-
t
mains near a quarter of an inch longer than
tke other.
Art
324 ESSAYS and OBSERVATIONS
Atr. XXII. • r
Some Observations on the new Method of cu¬
ring the CataraCl , by extracting the Cry flat-
line Humour ; by Thomas Young Surgeon
in Edinburgh
reftore loft fight, is recovering one
JL of the moft rueful of all the fenfes,
and the couching of the catarad, would be
one of the moft valuable operations, could
it always be done with fafety 5 but the bad
fuccefs, and dreadful confequences which
often attend it, have deterred many good
Surgeons from performing this operation,
and thrown it much into the hands of em-
pyrics.
I have couched but few in the old way,
and thofe with fuch bad fuccefs, that I was
fully determined to operate no more on the
eyes 5 nor did the fuccefs of the new method
performed by the ingenious M. Davie! , alter
my refolution for a confiderable time, til!,
at the importunity of feme of my betft friends.
f March 4. 2756,
PHYSICAL and LITERARY 325
I confented to try this new operation. Six
cataradts luckily call up laft fummer in the
Royal Infirmary at Edinburgh , which I ex¬
tracted in the following manner.
The patient being feated in a chair, with
an afiiftant at his back, to fupport his head,
and keep up his eye-lid, as in the old ope¬
ration, the operator may (land or fit in a
chair, as he finds moft convenient.
He fhould keep down the under eye-lid
with two fingers of the one hand, while with
the other, he takes the fmall knife A (Plate
VII. Fig . 3.) with which he pierces the trans¬
parent cornea at the external angle of the
eye, near to where the cornea joins with the
filer otic a > taking great care not to wound
the iris . Run the knife in a horizontal di¬
rection acrofs the anterior chamber, and
bring it out about the fame diftance from
the white of the eye, as where it entered ;
then cut that part of the cornea which lies
below the two orifices, as much in the form
of a crefcent as poffible, this makes the in-
cifion larger, and keeps the cicatrice more
off the fight ; lift up the flap of the cut
cornea with the fcoop B (Fig. 4.) or any other
convenient inftrument ; introduce at the
t T f *
fame
' ‘ 1 f r
326 ESSAYS and OBSERVATIONS
fame time a common couching needle C,
(Fig. 5.) thro’ the pupil, to open the capfula
of the cryftalline lens , that the latter may
come the more eafily out. A fmall aper¬
ture generally ferves this purpofe ; if the
lens is of a firm confiftence, it often flicks
to the point of the needle, fo that when the
inftrument is withdrawn the cryftalline comes
along with it 5 if it does not, a very gentle
preffure upon the eye forces it out. The
operation may be frequently performed with
the knife alone, the capfula of the cryftal¬
line being fometimes fo thin, that, after the
cornea is cut, a fmall preffure on the eye
makes the lens come away.
This method of operating is much the
fame with that pradifed by M. Daviel , which
you’ll find at large in the Memoirs of the A-
cademy of Surgery, voL ii. p . 337' I have
followed the example of the famous Mr.
Sharp , and fhunned the great multiplicity of
inftruments M. Daviel makes ufe of, which
renders this operation more fimple, lefs tedi¬
ous, and lefs dangerous.
I {hall next mention the fuccefs of each,
operation in the order they were performed.
1. Robert
PHYSICAL and LITERARY. 327
1. Robert Laurie, aged about 30 years,
was admitted into the Royal Infirmary with
a catarad in both eyes.
I operated on the left eye the 23d of
Jub 1755-
As foon as I had palled the knife into the
' ' . t
anterior chamber, he turned his eyes fo much
upwards, that the cornea was quite out of
fight ; I waited till the eye returned to its
former pofition, when ;I found the point of
the infirument in the ins, which I imme¬
diately difengaged, and finilhed the operation
without any other accident.
I expeded a great inflammation from the
iris being touched, but was agreeably difap-
pointed, finding the man recover with little
pain, no fever, and the inflammation incon-
fiderable.
About three weeks after the operation,
he could diftinguifh colours, and laro-e 0b-
jeds tolerably well 5 but could not bear
much light. His eye continued weak and
watery for about three weeks more, when
he could eafiiy fee a pin in the fleeve of his
own coat ; his eye was clear, but the pupil
not quite round, which was certainly owinu
to the iris being hurt*
2.
1 28 ESSAYS AND OBSERVATIONS
2e - - - — was admitted into the
Royal Infirmary about the middle of Septem¬
ber, with a catarad in the one eye, and the
cornea of the other quite opaque*
The pupil of the cataraded eye was con-
traded to above the fize of a large pin head,
but quite immoveable.
He was vifited by feveral Surgeons in
town, who were of opinion, that the dif-
eafe was incurable, , and that the bottom of
the eye was affeded, as well as the cryftal-
line lens,
I propofed trying the new operation, be¬
fore he fhould be diimififed incurable 3 to
which they very readily confented.
I performed it without any accident, and
the man recovered in a few days, without
any fever, pain, or inflammation. He was
difmiffed the houfe about a fortnight after
the operation, when his eye was quite clear,
but the pupil ftill immoveable 3 and he could
only perceive a glimmering of light, which
is more than was expeded from the ap¬
pearance of the pupil before the opera-
tion.
3. & 4. John Craig, aged about 40
years, was admitted into the Royal Infirmary
with
PHYSICAL and LITERARY, 329
with a cataradl in both eyes, which had
much of the milky appearance.
I operated on both eyes the 28th of Sep¬
tember 1 755, and nothing extraordinary oc¬
curred during the operation ; only, upon
dividing the capfula of the cryftalline, a fort
of milky liquor came out, and the lens was
of a dark-brown colour. He had a very
fpeedy recovery $ fix days after the operation,
I uncovered his eye ; he was capable of dif-
tinguiihing colours. I looked again into his
eyes on the 13th day, when I found his
fight ftiil better, and his eyes more able to
look at fmall objeds, without complain¬
ing.
He was difmified the houfe the 10th of
November , when he could read without the
affiftance of glafies.
5. Robert Laurie, whom I have al¬
ready mentioned, had the operation perform¬
ed on the right eye the 12th of Q£ioberf
when nothing extraordinary happened ; he
had a very good recovery, with fcarce any
pain or inflammation ; he was difmified from
the houfe the 19th of November , when he
faw very diflindlly with both eyes.
Vol, II. T t 6. Agnes
3i3o ESSAYS AND OBSERVATIONS
I 6. Agnes Barrowman, aged about 30
years, was admitted into the Royal Infir¬
mary, with catarads in both eyes.
I operated on the left eye the z6th of
O Bober 1755*
The fpace betwixt her eye-lids, when rai-
fed up, was fo fmall, that I could with dif¬
ficulty fee all the corneay which, in this pa¬
tient, was remarkably flat.
As foon as I had pafled the knife into the'
anterior chamber, fhe was feized with a fit
of coughing, which obliged me to cut the
cornea in a very great hurry. The opening
in the cornea was but fmall, which gave me
more difficulty in extrading the cryftalline,
than I had in any of the former.
' Notwithstanding this unlucky acci¬
dent, fhe had a tolerably good recovery \ her
eye was pained, and fomewhat inflamed, for
fometime after the operation, but never vio¬
lently. She was difmifled the houfe about
fix weeks after the. operation, being then
able to diftinguiffi very fmall objeds.
N-. B . Some eyes are more proper for this
operation than others ; the larger the eye,
and the more convex the cornea , the opera¬
tion, will be the eafier* This woman had a
remarkably
PHYSICAL and LITERARY. 331
remarkably bad eye in this refpedt ; it was
fmall, the cornea flat, and the diftance be¬
tween the eye-lids, when open, was very
little : perhaps the fpeculum oculi would be
of ufe to help all thefe faults while the cornea
is -cutting, but no longer, for fear of preffing
out the vitreous humour.
There was nothing particular in the treat¬
ment of thefe patients after the operation ;
it confifted chiefly in blooding, fpare diet,
now and then a gentle laxative, and cloths
dipt in vinegar and water applied frequently
to the eyes 5 they were not confined to their
beds above a day or two, and none of them
required fomentations.
I do not pretend, from the above cafes, to
make a companion betwixt the fuccefs of
couching, and the new method; this requires
more cafes than I have had oocafion to fee.
According to the trials made by fome of
«»
the Fre?:ch Surgeons, which you’ll find in the
Memoirs of the Academy of Surgery, vol. ii.
p. 578. the couching was the moft fuccefsfuL
Mr. Morand couched fix patients.
3 of them faw diftinTly.
3 of the catara&s role again.
Me
33z ESSAYS AND OBSERVATIONS
r
M. la Faye extracted fix catarads in the
new way.
2 of the patients faw diftindly.
2 of them faw lefs diftindly.
2 of them were quite blind.
M. Poyet extracted feven catarads after the
new method.
2 of h is patients faw diftindly.
2 of them lefs diftindly.
1 could diftinguifh light.
2 of them were quite blind.
Were I to judge from my own experience
in both operations, the new method certain¬
ly claims the preference ; fince I have only
operated upon fix cataracts, and all of them
have fucceeded, tho’ fome were not very pro-
mifing.
This, I hope, will excite others to make
further trials and improvements in this ope¬
ration.
Art.
PHYSICAL and LITER ARY. 333
S
Art. XXIII.
A Hernia from the Omentum falling down
into the Scrotum ; by Thomas Living-
ston , M. D . Phyfician at Aberdeen
Young man, aged about 28, of a very
JPx thin habit of body, and naturally of
a healthy conftitution, was feized with a
pain and uneafinefs about the region of the
ftomach ; for which complaints, (without
any regular advice) he took a vomit, which
operated in the ufual manner, but without
alleviating his former uneafinefs. In the
evening ot that day, about fix hours after
the operation of the vomit, he was feized
with fharp pains over all his belly, for which,
by the advice of a Phyfician, he was ordered
an emollient clyfter, and an anodyne at bed¬
time. The clyfter operated gently, and he
palTed the night pretty free of pain, till to¬
wards morning that the pain returned more
violent than ever ; particularly in the left
fide of the umbilical region, and in the left
tefticle.
* February 5. 1755.
334 ESSAYS and OBSERVATIONS '
tedicle. I was called to vifit him that fore¬
noon, and upon examination found a fcro-
tal hernia on the left fide, about the fize of a
large lift, extremely hard over all its fur-
face, and very painful on the flighted touch.
He had a hard frequent pulfe, intenfe third,
and all the other fymptoms of inflammation.
He was immediately blooded to a confider-
able quantity, warm dupes wrung out of an
emollient decodtion were alternately applied
upon his fcrotum and belly, and an emol¬
lient purgative clyder was injedted. The
application of the warm dupes gave him fome
fmall relief, and he imagined the parts were
fofter 5 but, upon ufing the taxis , the pain
was intolerable, and it was in vain to endea¬
vour to reduce the hernia . He continued in
this date till the evening, when his fever
demanded a fecond blooding, which was ac¬
cordingly performed ; another dimuiating
clyder was thrown up, and foon after he
had two or three copious dejedtions of in¬
durated faces. The operation of the clyder
gave him fome eafe ; but the date of the
hernia was not in the lead altered. He con¬
tinued redlefs and much pained all night,
and in the morning he drank the decoB . ta-
marindor .
PHYSICAL and LITERARY. 335*
marindor. cum dupl.fenna , which gave him fe¬
ver al loofe ftools throughout the day, the
hernia continuing as hard and painful as for-
, , *
merly.
He would not agree to have the operation
of the bubonocele performed, and in the even¬
ing his pulfe became feeble 3 he had fre¬
quent returns of a Jingultus , and died next
morning. It may be neceffary to mention,
that foon after the vomit he cried out, that
fomething was tearing his ftomach and guts
towards the bottom of his belly.
During his illnefs I was much perplexed
about the nature of the hernia . As the cly-
fters and ptifan had operated very naturally,
I could not imagine that it was any por¬
tion of the inteftines \ and as he was of a
remarkably thin habit of body, I could
fcarcely imagine that is was the omen¬
tum \ however, as his friends gave me the
liberty of examining the body, my doubts
and fcruples were foon fatisfied. I firft look¬
ed the ftate of the abdomen , where the fol¬
lowing appearances were very obvious. The
omentum fallen down, greatly ftretched, and
fo tenfe, that one fhould have imagined it
would have broke. The ftomach much dis¬
tended
336 ESSAYS and OBSERVATIONS
tended with air, the great curvature of it
much lower down than its natural fituation 5
the great arch of the colon quite out of its place,
and lying as low as the middle of the fmall
guts ; the jejunum and ileum confiderably in¬
flamed and much diflended with air, and
the mefenteric veffels much more turgid
than ufual. Thefe were the principal things
to be obferved in the abdomen . Upon ma¬
king an incifion through the teguments of
the fcrotum , (in the fame direction as is
ordered in the operation for the bubono¬
cele ) I foon difcovered the hernial fac,
which was very thin, tenfe, and rigid 5
and, upon laying the fac open, there was
nothing to be found but the omentum ,
which was compleatly mortified as high as
the ring of the mufcle. Upon dilating
the ring itfelf, I found a convolution of
the ileum flicking in the very mouth of the
opening, but the one half of the tranfverfe
diameter of the canal was only engaged,
and that part of it which was flrangulated
was in a mortified ftate. The remaining
part of the gut betwixt that and the ca-
fut colt was much fmaller than ufual, con¬
fiderably inflamed, and contained a little
PHYSICAL and LITERARY 33?
putrid vifcid chyle. Upon taking out the
omentum^ I found a refiftance towards the
lower part of the fcrotum, which I imagined
was owing to fome adhefion ; but, upon u«
ling a very gentle force, it was eafily ex¬
tracted, and plainly came out of the tunica va¬
ginalis tejlis , in which there was a pretty large
hole or perforation. The tefticle appeared
to be quite found. That portion of the 0-
mentum which was contained in the fcrotum $
weighed fix ounces and a half.
U u
VOL. II.
Art.
338 ESSAYS and OBSERVATIONS
Art. XXIV.
A Child brought forth at a Rent of the Belly
IN April 1736, Elfpet Grant i in the parifh
of Moy, being with child, took her la¬
bour-pains. After they had continued three
days with the child in the birth, two cracks,
as if the rafters of the houfe had broke,
were heard about the fick wife, and her bel¬
ly was rent from near the navel, with a
fquaint downwards and to the left fide, to
near the fhare-bone. At this rent the child
came into the world, the after-burthen was
brought away, and the intrails were feen.
The rent was cured without any other ap¬
plication, than that of butter mixed with
white fugar, and its fear was only as the
fcratch of a big pin.
These fads are attefted by the judicial
oaths of Anna Kennedy a midwife, and Mary
Ogihie a neighbour, who were prefent when
t
the rent was made and the child came out
of it ; of Margaret Dallas , who affifted to
bring
* May !. 1755.
PHYSICAL and LITERARY. 339
bring away the after-burthen ; of Robert
Smith who faw the rent and intrails imme¬
diately after this ; and of Ifobel Parrel , who
afterwards examined the fear : taken and
fubferibed by °James Macqueen younger of
Corribroughy Bailie to the Laird of Mackintojh ,
at Moyhall , November 22. 1738 ; of which
the original fubferibed copies are kept by the
Secretaries of the Philofophical Society of
. Edinburgh .
A Child efcaping at a Rent of the Womb in¬
to the Abdomen ; by Alexander Monro*
fenior , M. D. & P. A.
IN March 1744, I was defired by Mr.
Ramfay Surgeon here, to witnefs the exa¬
mination of the body of a woman who died
in child-labour without being delivered. The
account given me of this woman was, that
fhe was about 35 years of age, and had born
two dead children, and a living one. Being at
her full reckoning, her pains had begun on
Puefday morning, and continued in a natural
way, the child advancing towards the birth,
and
34 O ESSAYS AND OBSERVATIONS
and fome of the waters coming away all that
day and Wednesday , till Wednefday evening,
when fitting in a chair in labour, fhe gave
a fudden fpring from the chair, complaining
of violent pain in her belly. The child ne-?
ver was felt afterwards by thofe who attempt¬
ed to affifl: her delivery. She conftantly
complained of violent pain in her belly, with
her fenfes and judgment intire, till Friday
morning, when fhe died. On Saturday her
body was opened.
After cleaning away with fpunges a con-
liderable quantity of blood floating in the
abdomen , we faw a ripe child and its fecun-
dines lying in the lower part of it, a little to
the right fide. The child, placenta , and um¬
bilical rope were intire, and the membranes
were as ufuai after birth. The woman’s ute¬
rus had its fundus raifed as high as the navel,
with its iubftance foft and fpongy as is com¬
mon in pregnants, nothing preternatural
appearing in its fore- fide ^ but when the
fundus was turned down and forwards to¬
wards the of a pubis, a large rent four inches
long wras feen towards the neck of the womb ;
which being again put into its natural fitua-
tion, was opened its whole length, in the
middle
PHYSICAL and LITERARY. 341
middle of its forepart, when we had a bet¬
ter view of the rent, extending from very
near the os uteri upwards, a little obliquely
to the right fide. The os uteri was then ve¬
ry little open. The cervix which is diftin«
guifhable plainly frorli th tjundus in a woman
not with child, was here extended into the
fame common fac with it. The inner furface
of the womb was all fmooth, feeming to be
covered with a fine villous membrane. From
the larger fize of the finufes at the back and
upper part of the womb, I judged the pla¬
centa to have been formerly applied there,
. , >. 1 . * >
, • , ■■ ■/ iit.,. • i .) w
Art.
342 ESSAYS and OBSERVATIONS
Art. XXV.
A preternatural Collection of Waters in the
Womb with Twins ; by Stephen Fell
Surgeon in Ulverflone
IN November 1747, 1 was called to Hannah
SalthouJe} paother of feveral children,
then, according to her reckoning, in the
firft week of the eighth month of her preg¬
nancy. She had obferved her belly increa-
ling in bulk very fall during the preceeding
month, and particularly in the two laft weeks,
in every day of which a fenfihle difference
was faid to have been obferved . At my firft
vifit h er abdomen appeared to me much more
diftended than ever I had feen in a wo-
man with child, efpecially from the navel
to the upper part of the epigaftric region,
where it was more tenfe than towards the
offa pubis, and the moil ftretched part had
little fenfe of feeling. Her pulfe was high
and quick, her breathing was difficult, her
face
? February 6. 17550
PHYSICAL and LITERARY. 343
face was cadaverous, and (he had conti¬
nued unnatural labour-pains, with much
third: and little urine. The os tincct was
a little opened, but without any forming
of water that could be felt. I ordered
clyfters and an opiate at night, which made
her pafs it quietly.
Next day the pains were more natu¬
ral, and flae was tolerably eafy. In the
evening, fhe took an opiate with two
fcruples of pulv . ad partum , after which,
there were intervals between her pains j
but at four in the morning, fhe became
delirious, and appeared like one who had
not an hour to live. On taking rich hot
negus, thefe fymptoms went off 3 and then
having felt a child's head floating in wa¬
ter, I broke the membranes, and brought
away two male children, who were fcarce
half the fize of children born at the u-
fual time. One of them was dead, dwell’d
and livid 3 the other lived 64 hours, but
without taking food, or making any dis¬
charge by ftool or urine. The quantity
of water voided in this delivery was com¬
puted by all prefent not lefs than fix wine
gallons, 48 or 50 lib .
My
344 ESSAYS and OBSERVATIONS
Mr patient's Belly fubfiding to the natu¬
ral dimenfions, was fwathed immediately af¬
ter the after-burthen was brought away.
She had ftrengthening cordials and ano¬
dynes given her, with a proper diet, and
fometimes clyfters. Now, on the 12th day
after her delivery, Ihe appears out of danger.
Art,
PHYSICAL and LITERARY. 345
Art. XXVI.
Hi]} ones of tophaceous Concretions in the ali¬
mentary Canal 5 hy Alexander Monro
femor , M. D. F\ R. S. and ProfeJJor of
Anatomy in the Univerfty 0/^ Edinburgh
THE number of hiftories of tophaceous
concretions in the alimentary canal
is not fo great, but that your collection
might, in my opinion, admit of fome few,
efpecially if there is a variety in them.
Hifl. 1. A healthy boy, about twelve years
of age, began to complain of colic pains*
which increafing with frequent gripes, bor -
borygmi and vomiting, had fuch an effeCt,
that his parents aflerted, he was fcarce of fo
large ftature after fix years of his difeafe as
he was at the beginning of it. Vomits,
purges, vermifuges, attenuants, and a vari¬
ety of other medicines had been given in
that time without any benefit.
His father, one of the town-officers or
ferjea'nts, having then afked my worthy friend
Vol. II. X x and
* February 6. 1755.
34* ESSAYS and OBSERVATIONS
and collegue Dr. Plummers advice, he deft-
red my aftiftance. We were told by the lad,
who was greatly emaciated and very weak,
that fome years paft he had not had the vo¬
miting, but found a hard painful tumor above
the left groin, which fometimes fhifted place
a little, where he fancied often he felt fome-
thing like the flriking of two hard bodies on
each other. He had been of late much fa¬
tigued with tenefmus . Sometimes he had
no excretion of faces for feveral days, and
often he could fcarce make any water, and
that only in drops. During two days before
our vifit, the tenefmus was conftant, and he
felt fomething hard within the reBum near
to the anus , which he and feveral: others had
endeavoured in vain to bring away with their
fingers.
On extracting this fubftance with a for -
ceps , fuch as is ufed for extracting ftones
from the bladder, he was much eafier than
he had been of a confiderable time. Next
day, he paifed two other balls, and on each of
the two following days, a ball, which he could
not force out at the anus , was extracted with
the jorceps. After this, he had no uneafl-
nefs, ■
PHYSICAL and LITERARY. 347
nefs, and foon became a heal ftrong young
man. * ... .
The largeft of thefe five balls which was
the firft extracted, is five inches in circum¬
ference and fomething globular, but with
feveral prominences and flat furfaces. Moff
of the flat parts had a fmooth fhining tar-
9 x
tarous thin coat, the reft of it was more
rough and of a fpongy appearance. The two
laft brought away, are lefs iif bulk, and with¬
out fo much tartarous cruft. The two fmall
ones are all covered over with the fhining tar-
tarous cruft, which in feveral places is pret¬
tily variegated with different fhades of an
afhy colour. One of them has fome refem-
blance in its fhape to the fhell of a tortoife.
The other or fmalleft may be compared to
two pyramids joined by a common bafe.
The fecond in fize and the fmalleft are cut
thro’ near to the middle, where there is a
fmall flat bone, that probably has been the
the nucleus about which thefe balls were
formed, tho’ they are not of the fame
fnape.
We were informed by the parents, that
they had often chid their fon for i wall owing
the fmall bones of fheep and lambs feet, the
348 ESSAYS and OBSERVATIONS
finewy parts of which, when boil’d, the fa¬
mily frequently took for food.
Hift. 2. A man who had been long tor¬
tured with a painful hard fwelling in his
belly a little above the right groin, which
frequently caufed vomiting and diarrhoea,
tho’ at other times he was very cofiive, afk-
ed my advice, when he was very weak and
emaciated. The feat of this tumor , the kind
of feel it had thro’ the containing parts, and
its tumbling, as the patient faid, from one
place to another, when he changed poftures,
made me fufped a concretion to be lodged in
the great fac of the colon.
In hope to pufli it forwards in the colon , I
caufed his great guts to be filled with whey
Injeded by the anus , and then direded him-
felf and afiifiants to prefs repeatedly the tu¬
mor upwards. This manoeuvre being feveral
times renewed without fuccefs, I prefcribed
a brifk purgative, and ordered the injedions
with the preffure to be repeated as foon as
the cathartic began to operate. But this
and feveral other fuch operations failing, my
patient died.
Having obtained leave to examine his
body, niy conjedure proved to be right } for
PHYSICAL and LITERARY.
349
in the caput colt there was a ball of mor$
than feven inches circumference, with a de~
prellion at oppoiite ends. The inteftine had
contraded fo much at the fide of the ball next
to the cavity of the colon , that I could not
force it thro* the aperture there, but was
obliged to cut the fac in which it was lodged
to take it out.
The ball had no tartarous cruft on its fur-
face, and when it was cut thro', its ?iucleus
was a chalky or limy fubftance about the fize
of a common pea.
Hift. 3. Dr. John Stevenjon Phyfician gave
me a concretion fix inches in circumference,
the nucleus of which is a plumftone, taken
out of the inteftines of a boy of five years old.
Tho’ the ftone had been fwallowed long be¬
fore the boy’s death, the kernel of it was
fre/h when the ftone was taken from the
middle of the ball. A clyfter had brought
away feveral other plumftones from this boy
fome months after the plums had been
eat.
Hi ft. 4. Dr. Stevenfon alfo gave me ano¬
ther fuch concretion, which has four flat
fides with feveral deprefiions in them, mea-
furing about five inches in circumference,
formed
3 5o ESSAYS and OBSERVATIONS
formed alfo on a burnet plum (lone, which
he took out of the intehine of a girl.
Hift . 5. From the fame Gentleman I like-
ways had a third concretion pretty like to,
but a little larger than, the one defcribed and
painted by Dr. Simfon in Med. EJj\ vol. i.
art . 32, which, with three fuch others, he
took out of the intehines of another patient.
Each of them had a fmall hone in the mid¬
dle, the patient having formerly fwallowed
fmall hones and pebbles, for what he called
a colic in his homach.
The Dr. tells me, that all the fe three pa¬
tients wahed, without being fick or lofing
their appetite. They were fond of flefh for
food, and were averfe to flops. They feldom
were free of borborygmi , which made the
abdomen to change almoh conhantly its ap¬
pearance, the parts of it riling and finking
as the air went from one place to another.
Hiji. 6. In a ball of this kind eight inches
one way and fix the other, taken from a
Gentleman's intehines, whofe hihory I do
not know, the nucleus, is a little round piece
of wood about the lize of a common hazle
nut.
None
PHYSICAL' and LITERARY. 3ji
None of the balls mentioned in thefe
four laft hiftories have any tartarous cruft,
but they and all the other cut ones have the
appearance of being compofed of Jirata
furrounding the nucleus, their colour dif¬
fering in fhades from a dark rufty to a pale
aflhy colour. Their fubftance, except where
there is tartarous cruft, refembles a fine hat
or chamois-leather when cut.
Hijl. 7. In the collection of curiofities
kept by the Surgeons of this place, there
is a ball taken out of the ftomach of
a horfe, which is nearly fpherical, and
nineteen inches in circumference. Its
furface has fomething of the mulberry
form, being compofed of a great number
of hemifpherical knobs, about a quarter
of an inch diameter contiguous to each
other. Their outward (hell looks like a
thin cruft of fandy clay ; but within this
the fubftance has the fame matted appear¬
ance as the human concretions have.
Hi ft. 8. Balls are alfo frequently form¬
ed in the ftomachs of cows. Three of
them which were given to me, are al-
moft exaft fpheres of a black colour, com-
3J2 ESSAYS and OBSERVATIONS
pofed of an external hard tartarous cruft,
which is about — of an inch thick.
Within this there is nothing but fhort
black hairs matted compaftly together.
The circumference of the largeft is 9
inches 3 of the fecond, 6 3 and that of the
third, is 5-.
Art.
PHYSICAL and LITERARY, 353
Art. XXVII,
Remarks on Procidentia Ani, Intufufceptio,
Inflammation , and Volvulus of the Inte -
Jiines ; Alexander Monro fenior±
M. D. & P.A*'.
AT ftool more or lefs of the in fide of
the relfum is generally thruft out be¬
yond the verge of the anus , which afcends
when the preflfure of the diaphragm and ab¬
dominal mufcles ceafes. If the protruded
inteftine is not then retraced* it is fqueezed
by the fphinBer ani , fo that the return of li¬
quors from the part of it which is beyond
this ftridture, muft be rendered difficult ;
on which account, this part fwells, becomes
of a colour more red than natural, and a
larger than ordinary quantity of flime flows
from the ends of the vefiels that open on its
inverted villous furface. This ftate is called
procidentia ani ; a difeafe, to which chil¬
dren, old people, thofe weakened by difeafes,
or fuch as are attacked by tenefmusy from
Vol. II. Y y whatever
* February 6. 1755.
354 ESSAYS and OBSERVATIONS
v \r
whatever irritating caufe^ are more fubjed
than others.
The fpeedy reduction of the inverted pro¬
truded part of the inteftine, is the effectual
cure 5. nor fhould time be loft, as is often ad-
vifed, in trying to diminifh the fwelling by
warm fomentations and poultices, which re¬
lax the veiTels, and rarify the liquors, and
therefore produce an efifed very different
from what they are intended to have. * If
the prolapfed inteftine is fo much fwelled,
that it cannot be made to pafs thro5 the con¬
tracting fphindter , incifions may be made in
its furface, by which part of the dime and
blood contained in- the cellular membranes,
may be fqueezed out, to diminifh its volume,
and thus to make it capable of returning a-
gain within the body.
The pradice of the nurfes and other good
women, in making the redudion of a pro -
cidentiay is very faulty. They apply a warm
cloth to the protruded part of the gut, and
preffing on it, endeavour to thruft it all up
at once. Before the inteftine (wells, this o-
peration fometimes fucceeds with children
whofe fphin£ler is weak. But dry cloths or
fingers are liable to adhere to the villous coat
and
PHYSICAL and LITERARY. 355
and give great pain in taking them off. Thet
cloths or fingers applied here ought always
to be befmeared with oil, unfalted butter
or axunge, to prevent this adhefion. The
bulk of the prolapfed part is often fo
great, that it is impoffible to make it all pafs
at once thro’ the fpbinSter , and a fruitlefs at¬
tempt of redudion generally increafes the
fwelling. The redudion ought to be made
by preffing a fmall part of the fides of the
orifice, with a greafy finger, and when that
part is thrufl; within the orifice, another fin¬
ger is applied to what is then the verge of
the orifice to pufh it upwards, while the firft
applied finger is withdrawn : by fuch an al¬
ternate fuccefiion of two fingers, the whole
may be introduced in moft cafes without in-
cifions, fo that this difeafe is feldom fatal ;
and for that reafon, the patient is generally too
much negleded after the redudion is made,
which is fometimes attended with bad con-
fequences.
If, after the redudion, the part continues
to be pained and the patient’s pulfe is quick,
blood-letting, and a low cooling diet, are ne~
ceffary to prevent inflammation and its ccrnfe-
quences. In all cafes, too much coftivenefs
and
356 ESSAYS and OBSERVATIONS
and its contrary a diarrhcea> efpecially witl^
i tenefmus, are equally to be guarded againft $
feeing a return of the procidentia may be cau-
fed by either of them. The relaxed parts
are to be braced by ftrengthening topical me¬
dicines, In the aftringents commonly pre¬
ferred, I can have no confidence ; their ef¬
fect goes no deeper than the fkin ; but fti-
mulants, fuch as ardent fpirits or tinctures of
the aromatic refins made with them, give
a fpring to all the parts, and excite a glow¬
ing heat whenever they are applied, fo as to
touch any part of the extremity of the gut,
which they can always he made to do.
I have faid, that this difeafe, the prociden¬
tia ani , is feldom fata] $ and the redudion
of the prolapfed part of the intefrine into
the body, is generally regarded as a cure of
It ; but that this is not true, when the
doubling of the inteftine is high up, will ap¬
pear from the following hiftory.
A large-fized ftrong healthy boy, a year
and an half old, after a diarrhoea of fome
days, with tenejmus , was obferved to have a
procidentia ani , which was treated two days by
the women who attended him ; after which
Mr. Adam Drummond , Surgeon in this place,
■Jf i h i . i . : , ‘ 1- • V *■ • j
was
PHYSICAL and LITERARY. 3 $7
was called to his affiftance. He reduced the
procidentia frequently 3 but it foon returned*
which made him defire I fhould be con-
fulted.
The inverted inteftine flood out four
inches from the anus> without being much
fwelled or of a deep red colour* and the child
feemed to have no other difeafe. Mr. Drum¬
mond mo ft eafily introduced all the tumor in¬
to the body 3 but foon after it was pufhed out
again, upon the child’s having a defire to
ftool, notwithftanding a fervant’s keeping a
finger on each fide of the anus near to each
other, while feme liquid excrement was
palled. After the reduction was again made, I
put my finger, which is long, up the reSlum ,
pufhing the orifice of the inverted gut on
the point of it, and then found the orifice
of the inverted gut refembling the feel of the
os tincce of an unimpregnated womb refting
on it, which I could throw up fome way
further with a fudden jirk of the laft joint of
the finger, but without being able to invert
it. We then caufed a large quantity of milk
and water to be injedted with force, while
the two fides of the anus were prefled firmly
on the pipe of the fyringe introduced by the
anus
358 ESSAYS and OBSERVATIONS
«. •.* .. i * •
anus into the reBum^ to prevent the liquor’s
recoiling, in hope that the liquor would car¬
ry the inverted gut before it, to caufe its
return to the natural fituation. This opera¬
tion being repeated feveral times in vain, the
procidentia -always returning with the tenef-
mus , a very long probe of whale-bone was
made, a fponge was faftened round the
probe, this was wet in oil, the probe was in¬
troduced into the orifice, which, I faid, re-
fembled an os tincce^ the fides of which reft-
ed on the fpunge ; and with this the inte-
ftine was puftied a great way up into the bo¬
dy in the direction of the reBum , but with¬
out fuccefs. Several attempts of the fame
kind failing, we defpaired of a cure ; and
the child, fometime after, being attacked with
fevere vomiting and perpetual ienefmus , died
in few days.
Mr. Drummond , who opened the body,
told me, that the inverfion began a little below
the upper part of the figmoid flexure of the
colon ; and that the mefcolon was torn away
from the inverted part.
When a doubled part of an inteftine is
extended into the cavity of this alimentary
l'*- - canal,
PHYSICAL and LITERARY 359
canal, without appearing externally at the
anusy it is called intufufceptio , which, I am
perfuaded, is a much more frequent dif-
eafe than is generally thought. 1 have feen
feveral whom I judged to have died by it,
and Khali now relate the cafes of four people
whofe bodies were examined after death.
1. A middle aged woman, during fixteen
months before her death, fuffered greatly
from colic-pains, diftenfion of her belly,
vomiting, and tenefmus . In the latter part
of her life, when I firft faw her, flue had no
celfation from pain, except by the force of
opium *
In the great arch of the colon was a doubled
part of that gut, feven inches long. The
containing inteftine had a very flight adhe-
fion to the inverted doubled part contiguous
to it. The doubled part was of a dark red
colour, but not very hard. The paffage for
the paces thro’ it was very narrow, not al¬
lowing a finger pufhed with force to pafs.
2. A woman about fifty years of age lived
two years with fuch fymptoms as were oar*'
rated in the preceeding cafe. We found a
doubled part of the colon { our inches long in
the
1
360 ESSAYS and OBSERVATIONS
the left loin, with the fame appearance as de«
fcribed in the former hiftory*
3. A girl feven year old, after eating a
carrot and fome curren-berries, had a colic
which continued with a diftended belly, vo¬
miting, and palling With faces, from July
till the middle of December, notwithftand-
ing various medicines were given.
Mr. Malcolm Surgeon in Dalkeith , whofe
patient fhe was, being allowed to open her
corpfe, cut out the affe&ed part of the in-
Ceftine, and fent it to me. The end of the
ilium , valvula Dulpii , caput colt , and appen¬
dix vermiformi s , were raifed twelve inches
within the colon , to which they had a flight
adhefion. The outer furface of the con¬
tained inteftines was dark-coloured, and very
unequal. The orifice of the prolapfed part
was not at its end, but at one fide an inch
and a half from the end, with a foft flexible
prominence at each fide of the aperture,
which I judge to have been Tulpius s. valve.
The doubled parts were fo grown together,
that I could not diflinguifh one from the o-
ther. The paffage within them was fo fmall
and crooked, that I could not puih a probe
' thro’
PHYSICAL and LITERARY. 361
thro’ it ; but cutting it open gradually, I
found it was ftill pervious.
4. Dr. Cullen , ProfeiTor of Medicine in the
University of Glafgow, communicated the
following cafe to me.
A boy about twelve years, of age com¬
plained of wandering colic-pains, which he
imputed to blows received on his belly from
fome of his companions. Thefe pains re¬
turned frequently with diarrhcea , and fome-
times bloody ftools, for near a year, when
his parents confulted Mr. James Muir Sur¬
geon in Glafgow about him. The boy was
then much emaciated, had a quick pulfe, and
was fo weak as to be confined to his bed.
Two weeks after this, a livid membranous
fubftance, palled by the boy at ftool, was
brought to Mr. Muir who observing it to
be tubular, tied one end of it, and blowing
into the other, diftended it into fuch a con¬
voluted tube thirteen inches long, as you fee
reprefented ABC, Fig. 1. of Fab. VII.
which I caufed to be drawn from the origi¬
nal which was fent me. As it has the mefen-
tery D conneded to all its concave fide, it
appears to have been an intire piece of gut,
and not the villous coat only. Befides this
Vo l . II. Z z large
362 ESSAYS and OBSERVATIONS
large portion of inteftine, there were feveral
fhreds and fmaller pieces pafled by the patient ;
notwithftanding which, Mr. Muir faw after¬
wards, among the boy’s faces, fkins of po¬
tatoes which he had eat after thefe parts
©f the inteftine came away, fo that they had
not made any difcontinuity in the alimentary
canal. The fymptoms continuing, the boy
died in fix weeks.
Mr. Muir opened the body of his patient,
in prefence of feveral Gentlemen of the fa¬
culty, who faw what I am now to defcribe*
with the afliftance of a figure, which I cau-
fed to be taken of the dried preparation of the
inteftine fent me.
The folds of the inteftines and omentum
were all glued together by a fatty curdy
matter. Within four inches of the valve
of the colon, the ilium ABC, Fig. 2. Fab.
VII. formed into the ufual curve by the me-
fentery D, fuddenly rofe perpendicularly at E,
where it was much contracted and had the
appearance of a cicatrice. When the inte¬
ftine was opened, this contracted part of it
was found much thicker and harder than it
was any where elfe, efpecially on one fide,
where
PHYSICAL and LITERARY. 363
1
where it flood fo far into the cavity, as to
leave a very fmall paflage for the aliment.
Along this contracted part, the mefentery F
was firm and thick. After this, the inte^-
ftine G became of a natural enough form and
make.
The Gentlemen in Glajgow were, I think,
juftly of opinion, that the part of the inte-
fiine inflated by Mr. Muir , delineated in
Fig. 1. was an intufufcepted part fallen away
by gangrene from the inteftine at E in Fig . 2.
where, if there was a concretion, as is re¬
lated in cafe 3. it might have feparated with¬
out leaving any difeontinuity in the alimen¬
tary canal.
I have feveral times feen an intufufceptio
in the fmall guts of children, a little below
which I obferved feveral worms 5 but the
inverted part was neither fwelled nor dif-
coloured, v/hich made me think this difl
order had happened foon before death. In
one of them a lumbricus teres had pa fled the
half of its length thro’ a hole made in the
gut ; but, as there was no rednefs or other
O'
mark of inflammation at this part, I judged
the perforation to have been made by the
worm after the death of the fubjeCt.
There
3^4 ESSAYS and OBSERVATIONS
There Is little difficulty in conceiving
how a piece of a gut fhould enter doubled
into the part below it, and how it may be
gradually protruded downwards to a confi-
derable extent by the food or faces, in their
defcent towards the anus ; but it is not eafy,
when this difeafe begins, to diftinguiffi it
from a variety of other diforders which hap¬
pen in the alimentary canal, or to find a re¬
medy when it is fufpeded, efpecially if the
intufufceptio is in the fmall guts ; and from
the obfervation above narrated of the child
with the fatal procidentia ani , it would ap¬
pear difficult to cure it ; nay, if the doubled
parts of the inieftine are grown together, as
in moil of the hiftories, a reduction of it is
Impoffible* Nature feldom will perform
what I imagine ffie did in the laffc cafe, fe-
parate the doubled part, and unite what con¬
tained it. Nor do I believe any will be fo
hardy as to advife the amputation of the af¬
fected part of the gut»
'Tis furprfing howr the people in the pre¬
ceding hiftories lived fo long as they did,
with fuch large doublings of the inteftine,
and its mefentery preffed together within an¬
other
N
%
PHYSICAL and LITER ARY. 365
other piece of inteftine, when the common
inflammation of the inteftine often kills foon
thofe it attacks ; of which I could give nu¬
merous examples, hut {hall relate only one.
A Gentleman of weak nerves, and fubjeft to
flatus and pain in his ftomach, was feized with
a colic- pain about ten o’clock at night, for
which he fwallowed a fmall quantity of an
ardent fpirit. At three in the morning,
twelve or fourteen ounces of blood were let
from a vein in his arm, and a laxative dy~
fter was injefted, and operated well. At
eleven that forenoon I fir ft faw him, when
his friends thought him much better, being
free of pain 5 but as- his belly was greatly
fwelled and very tenfe, his pulle quick, fmall
and intermitting, his eyes languid, his coun¬
tenance faded, and a cold clammy fweat was
over all his body, I made the prognojis of
his having very few hours to live. He
died before five of the afternoon, fo that his
difeafe killed him in eighteen hours ; and I
have heard of others who died in lefs than
\
twelve hours after the firft appearance of
inflammation.
The
366 ESSAYS and OBSERVATIONS
The common practice of taking fpiritu-
qus liquors, or the warm carminatives, when
people feel colic-pains, is often unlucky,
and public warning fhould be given againft
it 5 for tho’ relief is found from fuch
things in the windy or fpafmodic colics,
which is not a deadly difeafe, yet they hurry
ofi the inflammatory ones fo faft, that they
foon prove mortal. I mult likeways think,
that writers on the inflammation of the in-
teftines don’t reprefent ftrongly enough the
languor and low fin all pulfe which fuch pa¬
tients generally have more than in moil
other djfeafes. It is fuch, that I have feen
feveral cafes, where people of fkill, decei¬
ved by thefe fymptoms, have been afraid to
order blood-letting, left the patient had not
ftrength to bear it, and thereby negleded
this evacuation till it was too late. When
there is a fixed pain in the ftomach or in-
teftines, with a quick tho’ fmail pulfe, no
time is to be loft 5 blood ought immediately
to be let plentifully, and venefedion fhould
be repeated till the pulfe becomes full and
free, which is a hopeful fign of a cure’s be¬
ing made, tho’ neither pain nor fever have
yet ceafed0
PHYSICAL and LITERARY. 367
The intufufceptio or inflammation, but e-
fpecially the latter, is generally the caufe of
what is commonly called the iliac paffion or
miferere ; for the volvulus or twifting a part
of the inteftines into a knot, which was
formerly faid to be the cafe, is generally
thought now, when anatomy is more culti¬
vated, and infpedtion of morbid bodies is
more univerfally allowed, to be an imaginary
evil. It is very rare, but not impoflible, as
will appear from the hiftory fubjoined to
this, and communicated to me by my Son.
Art.
368 ESSAYS and OBSERVATIONS
. > f , . . i w. ^ >■« Jl ■ ■■ • - , - ■ • *
• - - ■ ’ i} , ^ i (
Art: XXVIII. .
A Hiftory of a genuine Volvulus of the In-
teftines ; by Alexander Monro junior ,
M. D. and Profejjor of Anatomy f.
■ ' ■ ' : ■ ’ i") jff r '' ; i" !
AN old man complained of a colic, which
was neglefted more than two days $
when Mr. William Wood Surgeon in Edin
burgh being called, found him in the ago¬
nies of death. Next day I obtained leave to
open his abdomen , in prefence of feveral
ftudents of phyfic. We faw fourteen inches
long of the inteftinum ilium hanging in a firm
down in the pelvis , all black and mortified,
occafioned by a ftrangulation at the upper
part of the two pieces of the ilium which
formed the finus . The firm ftriclure there
was made by the appendix vermiformis , the
body of which lay behind the conflridted
parts of the iliumy while the end of it paf-
fing over and before them, had funk back
again into a plica of the mefentery, from
which, with great difficulty, I could draw
it ■
* February 6. 1755,
PHYSICAL and LITERARY 369
it out, for it was there extended into a glo¬
bular Ihape of three fourths of an inch dia¬
meter, by a glairy liquor, and was lodged
in a depreffion of the mefentery, the entry
to which was fmaller than the cavity where
the globular end of the appendix had been
lodged.
Vql. II.
1
i
37o ESSAYS and OBSERVATIONS
-c-l : ai !■ - ' A.
' ■ r> ••
" 1 :,rd ns . w. , - i c- -
Art. XXIX.
■> 4 * (.
% . , . . r* r ? r
e.J - - -
A Defer ft ion of the American Yellow Fever,
, m # Letter from Dr. John Lining Phy~>
Jician at Charies-tovvn in South Carolina*
to Dr. Robert Whytt Profejfor of Me¬
dicine in the Univerfty of Edinburgh *.
SIR , Charlestown, December 14. 1753.
£C T N obedience to your defire, I have fent
££ JL you the hiftory of the yellow fever as
€c it appeared here in the year 1748, which,
**'as far as I can remember, agreed in its
fymptoms with the fame difeafe, when it
£C vifited this town in former years. In this
£< hiftory, I have confined myfelf to a faithful
cc narration of fads, and have avoided any
£C phyfical inquiry into the caufes of the fe-
rc veral fymptoms in this difeafe ; as that
*c would have required more leifure than I
ffC am, at prefent, mafter of, and would per-
“ haps have been lefs ufeful than a plain de-
fcription.
1
* March 7. 1754,
PHYSICAL and LITERARY.. 37*
cc I wrote this hiftory, fo far as it relates
cc to the fymptoms and prognoses in the year
*c 1748, when we had the difeafe, laft ixi
fc this place 3 intending afterwards, if it re-
c< turned, to add, from further experience.,
€£ the method of cure, and likeways an ac~
cc count of any other fymptoms which might
££ attend it ; but, as no fuch opportunity
€£ has offered, I muR now omit that part.
<£ However, I hope the defcription which I
“ have given of this dreadful malady, which
*c fo frequently rages like the plague in the
c£ fouthern parts of America , is fo full, that
C€ a phyfician may, from thence, not only
C£ form a true judgment of its nature, but
<c likeways be able to deduce and communis
£C cate fome more certain method of cure,
C£ than has perhaps hitherto been ufed.
C£ I am forry I could not give a fuller
£C account of the diffedions of thofe who
*£ died of this difeafe, having unfortunately
*£ loft my notes taken from thofe di {Tedious.
I am , &c.
I. That
372 ESSAYS and OBSERVATIONS
HAT fever , which continues two. or
three days, and terminates without
any critical difcharge by fweat, urine, ftool,
&c. leaving the patient exceffively weak,
with a fmall pulfe, ealily depreffible by very
little motion, or by an eredt pofture j and
which is foon fucceeded with an idleritious
colour in the white of the eyes and the fkin,
vomiting, haemorrhages, &c. and thefe,
without being accompanied with any degree
of a febrile pulfe and heat, is called in Ame¬
rica > the yellow fever.
II. This fever does not feem to take its
origin from any particular conftitution of the
weather, independent of infectious miafmata ,
as Dr, Warren ^ has formerly well obferved.
For within thefe twenty five years, it has
only been four times epidemical in this town,
namely, in the autumns of the years 17^2,
39, 45 and 48, tho' none of thefe years (ex¬
cepting that of 1739, whofe fummer and
autumn were remarkably rainy) were either
warmer or more rainy (and feme of them
lefs
'* In his Treatife concerning the malignant fever in
^ ’’ ' > : i x i
PHYSICAL and LITERARY. 373
lefs fo) than the fummers and autumns were
in feveral others years, in which we had not
one inflance of any one being feized with
this fever ; which is contrary to what would
probably have happened, if particular confti-
tutions of the weather were productive of it,
without infectious mi aj mat a. But that this is
really an infectious difeafe, feems plain, not
only from this, that almoft all the nurfes
catched it and died of it; but like wife, as foon
as it appeared in town, it foon invaded new¬
comers, thofe who never had the difeafe be¬
fore, and country-people when they came to
town, while thofe who remained in the coun¬
try efcaped it, as likevvife did thofe who had
formerly felt its dire effeCts, thoJ they walked
about the town, vifited the lick in all the
different ftadia of the difeafe, and attended the
funeral of thofe who died of it. And laftly,
whenever the difeafe appeared here, it was
.eafily traced to fome perfon who had lately
arrived from fome of the Wejl- Indian Ilian dsP .
where it was epidemical. Altho’ the infection
was fpread with great celerity thro’ the town,
yet if any from the country received it in
town, and fickened on their return home, the
1 1
infeClion
374 ESSAYS and OBSERVATIONS
infection fpread no further, not even fo much
as to one in the fame houfe.
III. The fubjedts which were fufceptible
of this fever, were both fexes of the white
colour, efpecially ftrangers lately arrived
from cold climates, Indians * Mijlees , Mulat -
toes of all ages, excepting young children, and
of thofe only fuch as had formerly elcaped the
infedtion. And indeed it is a great happi-
nefs that our conftitutions undergo fuch alte¬
rations in the fmall-pox, meafies and yellow
fever, as for ever afterwards fecure us from
a fecond attack of thofe difeafes. There is
fomething very lingular in the conftitution
of the Negroes, which renders them not
liable to this fever; for tho’ many of thefe
were as much expofed as the nurfes to the
infe&ion, yet I never knew one inftance of
this fever among ft them, tho’ they are e-
qually fubjedt with the white people to the
bilious fever.
IV, This fever began in the middle or
rather towards the end of Anguf and con¬
tinued till near the middle of October, when
the weather became cold enough to prevent
its further progrefs. In the beginning of
Augiifts the weather was warmer than I had
ever
PHYSICAL and LITERARY. 37 5
ever known it in that month : the mercury
in Farenheit’s thermometer, for fome days at
\ *
2 o’clock p. m. rofe, in the fihaded air, to the
96th degree, at which time feveral people
died of apoplexies. The latter part of Augujl
and the firft week in September were much
more temperate ; the weather being then
much as ufual at that feafon of the year.
The fecond week in September was cold, the
wind being conftantly eafterly and the wea¬
ther cloudy 5 after which time I kept a re¬
gift er of the heat of the fhaded air ; an ab~
ftradt of which follows.
; ' ' ,s _ - * . » . • - - ' i
• * \ r •
.
In the latter part of September , and from
the 1 ft to the 18th of OSlobery
* * t
Septemb .
Qeiob
The mean heat at 2 p . m . was
72
65
The mean no&urnal heat was
68
1
54
The greateft heat at 2 />. m. was
79
75
The leaft heat at 2 p . m . was
60
52
The greateft nodurnal heat was
71
70
The leaft nodlurnal heat was
62
42
The greateft increafe of heat in
24
hours was
13
17
1 he greateft decreafe of heat in 24
hours was
9
22
In
376 ESSAYS and OBSERVATIONS
In all the month of September , and in
the greateft part of October, the wind wag
eafterly.
The depth of the rain in Augufl , Sep¬
tember and October refpedtively, was 6.881,
7.442 and 5*550 inches ; which, tho’ it ex¬
ceeded the rain of thefe three months taken
together at a medium, from the ten pre-
ceeding years, by 5.570 inches, yet it was
inferior to that which fell in the fame
months in feveral other years ; for in the
years 1747, 50, 51 and 52, there fell relpe-
dively, in thofe three months of thefe years,
above 21, 22, 24 and 26 inches of rain.
V. For a day or two before the attack of
the fever, people in general complained of a
headach, pain in the loins and extremities,
efpecially in the knees and calves of the legs,
lofs of appetite, debility and a fpontaneous
laffitude.
Some however were feized fuddenly, with-
any fuch previous fymptoms.
VI. After a chillnefs and horror, with
which this difeafe generally invades, a fever
fucceeded, in which,
1. The pulfe was very frequent till near
the termination of the fever, and was gene¬
rally
Physical and literary. 377
rally full, hard, and confequently ftrong : in
fome, it was fmall and hard, in others, foft
and fmall 3 but in all thofe cafes, it frequently
Varied in its fullnefs and hardnefs. To¬
wards the termination of the fever, the pulfe
became fmaller, harder, and lefs frequent.
In fome there was a remarkable throbbing
in the carotids and in the hypochondria ; in
the latter of wrhich, it was fometimes fo great,
that it caufed a conftant tremulous motion
of the abdomen .
2. The beat) generally, did not exceed
102 degrees of Farenheif s thermometer ;
in fome it was lefs, it varied frequently, and
was commonly nearly equal in all parts, the
heat about the pracordia being feldom more
intenfe than in the extremities, when thefe
were kept covered. In the firft day of the
difeafe, fome had frequent returns of a fenfe
of chilinefs, tho’ there was not any abate¬
ment of their heat. In a few, there hap¬
pened fo great a remiffion of the heat for
fome hours, when at the fame time the pulfe
/
was foft and lefs frequent and the fkin
moift, that one from -thefe circumftances
might reafonably have hoped that the fever
would only prove a remittent or intermit-
Vol. II. t B b b tent
378 ESSAYS and OBSERVATIONS
tent. About the end of the fecond day, the
heat began to abate.
3. The Jkin was fome times (tho* rarely)
dry ; but oftner, and indeed generally, it
was moift and difpofed to fweat.
On the firft day, the fweating was com¬
monly profufe and general 3 on the fecond
day, it was more moderate : but on both
thefe, there happened frequent and fhort re-
mi 11 ions of the fweatings ; at which times
the febrile heat increafed, and the patient
became more uneafy. On the third day,
the difpofition to fweat was fo much abated,
that the Ikin was generally dry ; only the
forehead and backs of the hands continued
- " ' ~ ■ . • t
moift.
4. The refpiration was by no means fre¬
quent or difficult, but was foon accelerated
by motion, or the fatigue of drinking a cup
of any liquid.
5. The tongue was moift, rough and
white, even to its tip and edges. On the
fecond day, its middle in fome was brown.
On the third day, the whitenefs and roughs
nefs of the tongue began to abate.
6. The thirji in very few was great.
7. A
PHYSICAL and LITERARY. 379
7. A naufea , vomiting or frequent Teachings
to vomit, efpecially after the exhibition of
either medicines or food, came on gene¬
rally the third day, as the fever began to
leflen ; or rather as the fulnefs of the
pulfe, heat, and difpofition to fweat began to
abate. Some indeed, but very few, on the
firft day, had a vomiting either bilious or
phlegmatic.
8. Very few complained of anxiety or
cppreffion about the preecordia or hypochon -
dria, nor was there any tenfion or hardnefs
about the latter.
9. On the firft day they generally dozed
much, but afterwards were very watchful .
10. Reftlefsnejs and almoft continual jaSta -
tions came on the fecond day.
11. A great defpondency attended the lick
from the firft attack.
12. The firength was greatly prof rated
from the firft attack.
13. The patn in the head , loins, &c. of
which they had complained (V) before the
attack, were greatly increafed, and in fome,
the pain in the forehead was very acute and
darting ; but thofe pains went generally off
the fecond day.
14. The
cn
8o ESSAYS and OBSERVATIONS
14. The face was flufhed, and the eyes
were hot, inflamed and unable to bear much
1 5. On the firft day, many of them, at
times, were a little delirious , but afterwards
not until the recefs of the fever.
’ 16. The blood faved at venaefedHon had not
any inflammatory cruft; in warm weather,
it was florid like arterial blood, and continued
in one foft homogeneous-like mafs, without
any feparation of the ferum after it was cold.
When there was any feparation, the crajja -
wientum was of top lax a texture.
17. The fools ^ after the firft day, were
fetid, inclined to a black colour, and were
very rarely bilious, foft or liquid, excepting
when forced by art ; for an obftinate coftive-
nefs attended the febrile ftate.
18. The urine was difcharged in a large
quantity, was pale, fometimes limpid, and
rarely of a higher than a ftraw colour, except
when the weather was very warm, and then
it was more faturated, of a deep colour, and
difcharged in fmaller quantities. It had a
large cloud, except when it was very pale or
limpid 5 but more generally it had a copious,
whitq.
PHYSICAL and LITERARY. 381
white fediment, even in the firft day of the
fever.
On the fecond day, the urine continued to
be difcharged very copioufly $ in fome, it was
then turbid, and depofited a more copious fedi¬
ment, than on the firft day 5 this fediment was
fometimes of a brown ifh colour ; in which
cate it was generlly followed by bloody urine,
either about the end of the fecond or begin¬
ning of the third day. The colour and quan¬
tity of the urine, difcharged in equal times,
were remarkably variable, being now limpid,
then of a deeper colour, now difcharged in
a larger, then in a fmaller quantity, which
could not be afcribed to any change made
either in the quantity or quality of the
drink, &c.
VII. The fever accompanied with thofe
(VI.) fymptoms, terminated on the third day,
or generally in lefs than 72 hours from the
firft attack, not by any afiimulation, or cotfti-
on and excretion of the morbid matter ; for
if by the latter, there would have been fome
critical difcharge by fweat, urine, ftool, or
otherways, none of which happened ; and
if, by the former, nothing then would have
remained but great debility. No ; this fever
did
3 32 ESSAYS and OBSERVATIONS
did not terminate in either of thefe falutary
ways, excepting in fome, who were happy
enough to have the difeafe conquered in the
beginning by proper evacuations, and by
keeping up a plentiful fweat, till the total fo-
lution of the fever, by proper mild diapho¬
retics and diluents. But thofe who had not
that good fortune, however tranquill things
might appear at this period, (as great debi¬
lity and a little yellownefs in the white of
the eyes, feetrfd then to be the chief com¬
plaints, excepting when the vomiting con¬
tinued), yet the face of affairs was foon chan¬
ged 3 for this period was foon fucceeded by
the fecond Jiadium 3 a Rate, tho5 without any
fever, much more terrible than the firft :
the fymptoms in which were the following.
VIII. 1. The pulfe, immediately after the
recefs of the fever, was very little more fre¬
quent than in health, but hard and final ft
However, tho5 it continued fmall, it became,
foon afterwards, flower and very foft 3 and this
foftnefs of the pulfe remained as long as the
pulfe could be felt. In many, in this ft age
of the difeafe, the pulfe gradually fub-
fided, until it became fcarce perceptible 3 and
ibis, not with handing all the means uied to
fupport
PHYSICAL and LITERARY. 383
fupport and fill it • and when this was T the
cafe, the i&eritious-like fuffufion, the vo¬
miting, delirium , reftlefsnefs, &c. increafed
to a great degree. In fome, the pulfe, af¬
ter being exceedingly fmall and fcarce per¬
ceptible, recovered confiderably its fullnefs ;
but that favourable appearance was generally
of but (hort continuance.
2. The heat did not exceed the natural ani¬
mal heat ; and when the pulfe fubfided, the
fkin became cold, and the face, breaft and ex¬
tremities acquired fomewhat of a livid colour.
3. The Jkin was dry when the weather was
cold, but was moift and clammy when the
weather was hot.
4. The refpiration was natural or rather
flow.
5. The tongue was moift and much clean¬
er than in the former (VI. $.) ftage, its tip
and edges, as alfo the gums and lips, were
of a more florid red colour than ufual.
6. Very few complained of thirjl , tho’
they had a great defire for cold liquors.
7. The *' vomiting or reaching to vomit in¬
creafed, and in fome was fo. conftant, that
neither medicines nor aliment of any kind
were retained. Some vomited blood ; others
only
0
384 ESSAYS; AND OBSERVATIONS
oniy what was laft exhibited, mixed with
phlegm ; and others again had what is called
the black vomit The reaching to vomit
continued a longer or fliorter time, according
to the ftate of the pulfe ; for as that became
fuller, and the heat greater, the reaching to
vomit abated, and e contra. .
8. The
* That which is called the black vomit, at ArA fight, ap*
pears to be black ; but on a more careful examination, I
obferved, that this Colour proceeded from a great quantity
offmall, flakey, black fubfiances which floated in the liquor
thrown up by vomit ; but the colour of this liquor was
much the fame with that which the patient had laft drank,
and was by no means black. Thofe black flakey fubfiances
are the bile mixed with, or adhering to the mucus which
lined the fiomach. For, upon difledion of thofe who died
of this difeafe, not only in this but former years, I always
obferved that the mucus of the fiomach was abraded, and
the bile in its cyJHs was black and fometimes very vifckh
In a Lad who died of this difeafe in the beginning of the
fourth day, and who was immediately opened, the bile was
not only black, but had the confifterTce of thick Venice- tur¬
pentine, and was exceedingly tough. On the infide of the
fiomach, there werefeveral carbuncles or gangrenous fpecks*
And in all thofe I have difleded, who have died of this dif¬
eafe, I have not only always obferved the fame, but like-
ways that the blood was very fluid, and the vefiels of the
<vifcera much diftended ; from whence I have been very in¬
clinable to think, when the difeafe was not conquered in its
firfi jladium , that, about the time of the termination of the
fever, there was a metajlafis of the morbid matter to the
mfcera .
PHYSICAL and LITERARY. 385*
8. The inquietude was very obftinate, and
when they dozed, their {lumbers were but
fhort and unrefrefhing. There were fome
who were drowfy ; but thefe always awaked,
after the fhorteft {lumbers, with a great de-
jeftion of fpirits and ftrength.
9. The jactations or reftleftnefs was fur-
priling ; it was frequently fcarce poffible to
keep the patients in bed, tho’, at the fame
time, they did not complain of any anxiety
or uneafinefs 5 but if afked how they did,
the reply was, Very well.
10. The debility was fo great, that, if the
patient was railed eredt in the bed, or, in
iome, ii the head was only railed from the
pillow, while a cup of drink was given, the
pulfe funk immediately, and became fome-
times fo fmall, that it could fcarce be felt ;
at this time, they became cold, as in a hor~
ripilatio , but without the anferine-like {kin :
tneir {kin became clammy, the delirium in-
created, their lips and fkin, efpecially about
the neck, face and extremities, together
with their nails, acquired a livid colour.
1 r. The delirium returned and increafed ;
it was generally conftant in thofe whofe pulfe
was final! and fubfiding.
Vol. IL C c c
12. The
rat 6 ESSAYS and OBSERVATIONS
12. The inflammation of the tunica con -
jun&iva or white of the eyes increafed much>
but without pain.
13. A yellownefs in the white of the eyes,
if it did not appear before in the febrile
Rate, became now very obfervable, and that
idteritious-like colour was foon diffufed over
the whole furface of the body, and was con¬
tinually acquiring a deeper faflfron-like co¬
lour. In fome indeed no yellownefs was ob¬
fervable, excepting in the white of the eyes,
until a little before death, when it increafed
furprifingly quick, efpecially about the bread:
and neck.
14. There were many fmall [pecks , not
raifed above the fkin, which appeared very
thick in the bread and neck 5 but lefs fo in
the extremities, and were of a fcarlet, purple
or livid colour.
15. In women the menjirua flowed, and
fometimes exceffively, tho* not at their regu¬
lar periods.
16. There was fuch a putrid diflolution
of the blood in this Jiadium of the difeafe,
that, befides the vomiting of blood former¬
ly mentioned, and the bloody urine foon to
be taken notice of, there were hcemorrhagies
from
PHYSICAL and LITERARY 387
from the nofe, mouth, ears, eyes, and from
the parts which were bliftered with cantha~
rides. Nay, in the year 1739 or 1745, there
was one or two inftances of an haemor¬
rhage from the fkin, without any apparent
pundture or lofs of any part of the fcarf-fldn.
17. An obftinate cojlivenefs continued in
fome 3 in others, the ftools were frequent
and loofe 3 in fome, they were black, li¬
quid, large and greatly fatiguing 3 in others,
when the ftools were moderate, even tho*
they were black, they gave great relief 3 in
others again, the ftools nearly refembled tar
in fmoothnefs, tenacity, colour and con-
fiftence.
18. The urine was difcharged in a large
quantity, in proportion to the drink retain¬
ed by the patient : it was pale if the patient
was not yellow 3 but if yellow, then it was
of a deep faffron-colour 3 in either cafe, it had
a fediment, or at leaft a large cloud, which
remained at the bottom of the glafs 3 in
fome, it was very turbid, in others, it was
bloody, and the quantity of bKnd difcharged
with the urine bore always fome proportion to
the ftate of the pulfe 3 when that became
fuller, the quantity of blood in the urine was
diminiihed ;
\
3n ESSAYS AND OBSERVATIONS
diminifhed : when the pulfe fubfided, the
bloody urine increafed, and even returned af¬
ter it had ceafed feme days, foon after the
pulfe became fmaller.
This Rage of the difeafe continued feme-
times feven or eight days before the patient
died,
*
IX, When this jiadium (VIII.) of the dif¬
eafe terminated in health, it was by a recefs or
abatement of the vomiting, haemorrhagies,
► ,
delirium , inquietude, jadations, and ideri-
tious-like fuffufion of the fkin and white of
the eyes ; while, at the fame time, the
pulfe became fuller, and the patient gained
ftrength, which, after this difeafe, was very
flowly.
But when it terminated in death, thofe
(VIII.) fyoiptoms not only continued, but
fooner or later increafed in violence, and were
fucceeded with the following, which may
be termed the third jiadium of the diieafe,
which quickly ended in death,
X. The pulfe tho’ foft became exceeding¬
ly fmall and unequal ; the extremities grew
cold, clammy and livid ; the face and lips,
in feme, were flufhed ; in others, they were
of a liyid colour ; the livid fpecks increafed
PHYSICAL and LITERARY. 389
fo faft, that in fome, the whole breaft and
neck* appeared livid ; the heart palpitated
ftrongly ; the heat about the prczcordia in-
creafed much *3 the refpiration became dif¬
ficult, with frequent fighing ; the patient
now became anxious, and extremely reftlefs ;
the fweat flowed from the face, neck and
breafl ; blood flowed from the mouth, or
nofe or ears, and in fome, from all thofe
parts at once ; the deglutition became dif¬
ficult ; the hiccoughs and Jubjultus of the
tendons came on, and were frequent ; the
patients trifled with their fingers, and picked
the naps of the bed-cloaths 5 they grew co-
matous, or were conftantly delirious. In
this terrible ftate, fome continued eight, ten
or twelve hours before they died, even after
they had been fo long fpeechlefs, and with-*
out any perceptible puliation of the arteries
in the wrifts whereas, in all other acute
difeafes, after the pulfe in the wrifts ceales,
death follows immediately. When the dif-
eafe was very acute, violent convulfions feized
the unhappy patient, and quickly brought this
ftadium to its fatal end. After death, the li¬
vid blotches increafed faft, efpecially about
the face, breafl, and neck, and the putre¬
faction
g9o ESSAYS AND OBSERVATIONS
fadion began very early, or rather increafed
very quickly.
XL This was the progrefs of this terrible
difeafe thro’ its feverai Jiadia. But in hot
weather, and when the fymptoms in the firft
ftage were very violent, it palled thro’ thofe
ftages, as Dr. Warren has like wife obferved,
with fuch precipitation, that there was but
little opportunity of diftinguifhing its diffe¬
rent Jiadia 5 the whole tragedy having been
finifhed in lefs than 48 hours.
XII. It was remarkable, that, 1, The
infedion was increafed by warm and leffened
by cold weather. 2. The fymptoms in the
feverai jiadia were more or lefs violent, ac¬
cording to the heat or coolnefs of the wea¬
ther. In hot days, the fymptoms were not
only more violent, but in thofe who feemed,
in moderate weather, to be on the recovery,
or at lead: in no danger, the fymptoms were
all fo greatly heightened, when the weather
grew confiderably warmer, as frequently to
become fatal. In cool days, the fymptoms
were not only milder, but many, who were
apparently in great danger in hot days, were
faved from the very jaws of death by the
weather becoming happily cooler. 3. The
difeafe
PHYSICAL an v LITERARY. 391
difeafe was generally more fatal to thofe who
lay in fmall chambers not conveniently fitu-
ated for the admiflion of frefh air, to thofe
of an athletic and full habit, to ftrangers
who were natives of a cold climate, to thofe
who had the greateft dread of it, and to
thofe, who, before the attack of the difeafe,
had overheated themfelves by exercife in the
fun, or by excefiive drinking of ftrong li¬
quors 5 either of which indeed feemed to
render the body more fufceptible of the in¬
fection. Laftly, the difeafe proved moft
certainly fatal to valetudinarians, or to thofe
who had been weakened by any previous
difeafe.
XIII. The prognojlics in the firft Jladium
are thefe, 1. The more acute and conftant
the pains are in the head, loins, knees, &c.
the more the eyes are inflamed 5 the greater
their inability is to bear light, and the more
the face is flufhed at the firft attack, the
fever and all the fymptoms (VI.) in the firft
fladium will be the more violent. 2. The
more intenfe the fymptoms are in the firft
ftate, the fooner will the fever terminate.
3. The fooner the difeafe runs thro’ the firft
Jladium , the fhorter will be the duration of
the
$92 ESSAYS AND OBSERVATIONS
•» ' t* ■* v
the fecond, & e contra 4. The fhorter the
duration is of the fir ft, the greater and more
certain is the danger in the fecond hate.
For when the fever terminated, before the
beginning of the third day, death feemed
inevitably to be the confequence, as there
was then no poflibility of fupporting the
pulfe, and as all the bad fymptoms were
then hurried on with fuch precipitation, that
the patient generally died before the end of
the fifth day, excepting a confiderable cool-
nefs of the weather happily interveened ; but
on the contrary, it was a favourable circum-
fiance when the fever was protraded to the
end of the third day, without any remarkable
hardnefs or deprellion of the pulfe. 5. A
great depreffion of the pulfe, about the ter¬
mination of the fever, is bad, fince, from
that circumflance, the vomitings, inceffant
jadations, the coldnefs and lividnefs of the
extremities, haemorrhagies, delirium , &c. are
u file red in with furprifing celerity. 6° The
more the ftrength is proftrated from the
frft attack, the greater is the danger. 7.
A vomiting coming on early in the difeafe,
and continuing or increafing, is bad, and
generally prefages the black vomit. 8. A
fediment
PHYSICAL and LITER ARY.; S93
fediment in the urine in the firft and fecond
day of the difeafe is bad, and the more
copious the fediment is, the greater is the
danger.
XIV. The prognoftics in the fecond Jla -
diurn are thefe : i. An early yellownefs in
the white of the eyes is bad : when it is
obfervable about the end of the fecond day,
in the firft ftadium , the patient generally dies
about the beginning of the fourth day from
the firft attack of the difeafe. But when
• 1 w * - •' 5
the yellownefs does not appear till the end
of the third day, if the patient does not re¬
cover, the difeafe fometimes continues to
the 9th or 10th day of the fecond Jladium
before the patient dies. When the yellow¬
nefs of the fkin and eyes increafes fall and
acquires foon a deep ifteritious-like colour,
the greateft danger is to be apprehended.
2. If the inflammation of the white of the
eyes increafes, it is bad. 3. The more in¬
flamed and bloody-like the fkin is where it
has been buffered, the greater is the danger.
4. If the vomiting continues or increafes, it
is bad, but the black vomiting is generally
mortal. 5. When the pulfe varies frequently
in its fullnefs, being fometimes fmall, then
Vol. IL D d d fuller
394 ESSAYS and. OBSERVATIONS
fuller, it is bad. But there was lefs de-'
pendente to be had on the pulfe in this than
is common in other difeafes ; for in fome
patients, in the fecond ftage of the difeafe*
even within a few hours of their death,
the pulfe, with refpedt to its fullnefs, foft-
nefs, equality and frequency, has continued
like that of one in perfect health, aItho’y
from the other fymptoms, the death of the
patient could be foretold with great cer¬
tainty. 6. The more the ftrength of the
patient is reduced in the firft, the greater is
the danger in the fecond Jladium. 7. Great
reftlefnefs, inquietude, an early delirium and
a continuation of it are very bad. 8. Livid
blotches about the neck and breaft, a livid-
nefs of the lips and nails, fluffing of the'
face, or a livid colour thereof, are fure figns
of the quick approach of death. 9. Fre¬
quent loofe (fools, which give not any re¬
lief, are bad, and the fooner they fponta-
neoufly happen, the greater is the danger r
but thofe which are black, and continue fo
without any abatement of the fymptoms, are
generally mortal. 10. Bloody urine and all
hsemorrhagies, excepting flight ones from
the nofe, are bad y and the more copious
‘ 4 . they
PHYSICAL and 'LITERARY, 395
they are, the greater is the danger. But a
flux of the menfes , tho’ not at their regular
period, if attended with an abatement of the
fymptoms, is a favourable circumftance, o-
therwife it is bad. 11. A fuppreflion of
urine, efpecially in thofe, who, in the courfe
of the difeafe, have had large difcharges that
way, is a certain fign of the quick approach
of death.
XV. As to the prognoftics in the third
(X) Jiadium , it is fufficient to fay
£C Nature, alas ! was now furpriz’d,
{C And all her forces feiz’d,
cc Before fhe was how to refift advis’d *.
* Dr. Sprat's Account of the plague of Athens.
Art.
39$ ESSAYS and OBSERVATIONS
Art. XXX.
Anfwer to an Objection againft Inoculation %
by Ebenezer Gilchrist M. D. Phyfi -
dan at Dumfries \
INoculation has been pradifed here a-
bout five and twenty years, twenty al-
moft conftantly. The fuccefs of it foon de-
monftrated the great advantage and neceffity
of it, efpecially in a place long remarkable
for bad fmall-pax. A letter I wrote two or
X * * _ \ •
three years ago to a Gentleman, who afked
my opinion and advice for his children, was
a means of introducing it into a part of the
country where it had never been tried.
While many were difpofed to come into it,
there were not wanting fome, as in all fuch
cafes, to oppofe it tho’ in a pretty large
trial of it, at the time, it had fucceeded to
the joy and fatisfadion of all who w liked
well to it. Amongft other objedions, one was
more pofitively infifled on ; which, indeed,
were it as well founded as it is fpecious.
^ February 5. 1756,
PHYSICAL and LITERARY. 397
would effectually put to filence the warmed
advocates for inoculation, and overturn alto¬
gether the pradice. A proper anfwer was
made to it 5 and perhaps I fhould have
thought no more of it, had I not been in¬
formed fometime after, that, in a fociety of
ingenious Gentlemen, who made matters of
this kind the fubjeds of their debates and in¬
quiry, the fame objection was taken notice
of, and feemed to make an impreffion.
Pains were taken to undeceive them alfo.
The objection, to give it in the words of
my friend’s Letter, is this : “ The fmall-
“ pox, in the ordinary way, is defigned by
“ nature as a drain to clear the conftitution
“ of fome grofs humours, which, if not car-
“ ried off in this way, would bring on other
“ dangerous difeafes ; and for moil part end
“ in death, before perfons arrive at middle
“ age. Now, fay the ObjeCtors, the fup-
f‘ puration where the fmall-pox is inoculated,
“ is fo inconfiderable, that it cannot be fup-
“ pofed fufficient to clear the body of thofe
“ humours which are the parent of other
“ deftruCtive diftempers. Eefides, fay they,
this theory is juftified by fads and expe-
'■ Hence. Upon inquiry, it is found, that
v “ in
398 ESSAYS and OBSERVATIONS
(C in thofe places where inoculation has mo ft
cc prevailed, particularly in and about Dum -
*c fries, there are as many that die in child-
“ hood, and before they arrive at the age of
twenty, as formerly, even including thofe
ec who are cut off by the fmall-pox. If this
fC is the cafp, then inoculation is to no pur-
“ pofeA I fhall not trouble you with what
occurred to me in anfwer to this objection!
I greatly fufpedt the foundnefs of the prin¬
ciple on which it is built, and have ventured
to deny the truth of the facft. How trifling
foever you may think the objection, yet, as
there is great ftrefs laid upon it, and by per-
fons of rank, I thought it might not be im¬
proper to apprife you of it Thus far my
friend.
An objection fo plaufibly formed, and with
fuch particular application, feems to affeff,
more than any thing I have feen advanced,
at once inoculation itfelf, and indiredtly all,
who, from a ferious perfuafion of its ufeful-
nefs, have fhewn themfelves induftrious to
promote it. To encourage and recommend
a practice more hurtful in its confequences,
than the immediate good of it can be of fer~
vice, which could not efcape the obfervation
' of
Physical and literary. 399
of every one, fuppofes want of attention at
lead, or fomething wprfe. Yet not fo much
to obviate a reflexion of this kind, becaufe
I believe undefigned,, but for a more im¬
portant reafon, have I thought it demanded*
a public animadverfion*
In order to fatisfy myfelf fully and others,
I have not trufted wholly to my own opinion ;
but converfed with all who have been loner
and principally concerned in inoculating,
thro’ an extenflve country : and we can af¬
firm that of the inoculated, few are dead.
Two or three of a hundred are the utmod
we can recoiled: : but fuppofing them more,
it is far fhort of the number that in ordinary
circumflances die before twenty. Nor are
we miftaken, do we think, when we fay,
that they are uncommonly healthy ; which
the fmall proportion that are dead will rea-
dily fugged to every one. It is impoflible to
be very exad 5 but it is diffidently evident
to us, that the date of the inoculated is much
the reverfe of what is objeded. If this is
true every where, as here it certainly has
been hitherto, we are led to a very material
difeovery ; and that which was intended
as an unanfwerable objedion, by giving oc-
cafion
400 ESSAYS and OBSERVATIONS
cafion to a pretty careful inquiry, has acci¬
dentally furnifhed a new argument in favour
of inoculation, and a further proof of the
great benefit of it. Long ufe has fhewri it
to be immediately a real fecurity againft the
prevailing malignity of a very mortal dis¬
temper j and the prefent inftance affords a
flrong prefumption that it is, in its confe-
quences, no lefs a prefervative from many
difeafes incident to a period of life the mofl
fatal to mankind.
As to the theory in the objedion, it is
more philofophical perhaps to argue thus :
The fever of the fmall-pox, communi¬
cated in the infant-ftate, not only deftroys
or expells the latent feeds of difeafes, before
they are, by time and accidents, perfected and
put into adion, but caufes fuch an altera¬
tion of the humours as may make them
lefs fufceptible of any morbid impreffions :
and the veffels being fo foon accuftomed, be¬
fore they become rigid, to certain motions and
extenfions, the body is rendered ever after
more paffive to the impulfes of any fubfe-
quent diftemper ; which therefore will be
attended with lefs danger. This is agree¬
able
PHYSICAL and LITERARY. 4or
able to experience 3 for one who has fuffer-
ed an acute illnefs, will bear ficknefs better
than another who never had the like dif-
temper, and be lefs overcome by it.
From fuch reafonitig it will feem to Fol-
low, that the fooner inoculation can be per¬
formed with fafety, the greater will be the
advantage. I cannot aflfert, that to this is
owing the more than ordinary healthfulnefs
of the inoculated with us, and that fo few
X
of them are dead : but if nothing forbid*
I always advife it, the child yet unwean¬
ed 3 and with me it has always happily and
pleafantly fucceeded. Though many have
been inoculated before the fixth month, I
chufe to delay it till this time, or any conve¬
nient time after, unlefs the fubjedt is big and
ftrong. Then, betides the greater pli¬
ancy, or kindly yielding of the folids, the
blood has not, from the ufe of animal
food, acquired an' inflammatory difpofition,
and the humours a vicious taint. The
firft paflages are not, as at a more advan¬
ced age, difordered by worms or other foul-
nefies. A formal preparation, the juices be¬
ing all fweet and found, is very little ne-
ceflary : and the continual dread and dan-
Vol. II. Fee p-er
402 ESSAYS AND OBSERVATIONS
ger of the natural infeftion is early removed ^
a matter, in this cafe, both for parents and
children, not lead: to be confidered. Teeth¬
ing, I know, is made the great objeftion
here ; but from this I have met with fo
little difficulty, that I mgke no fcruple, ex¬
cept in a few circumftances, which may be
eafily difcovered and avoided.
PHYSICAL and LITERARY. 403
Art. XXXL
A Propofal of a new Method of curing ob-
JiruSled Menfes ; by Dr. Archibald
Hamilton Phyfician in Edinburgh *.
„ *
* • • ■ . • «
IN a converfation I had fometime ago with
my friend Dr. Hunter , now Phyfician
in Beverley , concerning the cure of fome
particular difeafes, I remember he propofed
a method of removing obftrudions of the
menftrua by a mechanical compreflion of the
external iliacs. I thought, from the anato¬
mical ftrudure of the parts, the propofal
pretty reafonable in fome cafes ; and refol-
ved to put it into pradice, the firft favour¬
able cafe that occurred to me. About fix
months ago, I was fent for to vifit a girl be¬
twixt nineteen and twenty years of age, who
had been obftruded for near feven months,
occasioned by fuddenly expofing herfelf to
cold, during the time file was menftruating.
From the firft appearance of her catamenia ,
to the time of their ftoppage, (he had enjoyed
a
9 May 1. 17 55.
2p4 ESSAYS and OBSERVATIONS
a very good ftate of health. She had con-
fulted no regular praditioner ; hut had ta¬
ken a few things, without any relief, that
fame of her female acquaintance had defired
her. Her complexion was a little pale and
wan. Her appetite and digeftion bad, with
eradiations, and fometim.es fwelling of her
ftomach. She had now and then fickifh
and fqueamifh fits, with inclination to vo¬
mit. Her pulfe was flow and languid, with
a great l3affitude and inadivity of body, not
having a defire to take her ufual exercife.
On inquiry, I found fhe never had any. .puN
monte diforder, nor at prefent any complaint
or uneafinefs of her breaft. She had alio no
pain or fwelling about the pude?2da . It now
wanted about twelve days of the ufual time
of the approach of her menfes, I defired her
to receive the fleam of warm water, every
night at bed-time, upon the pudenda , in or¬
der to relax thefe parts, fo that the blood
might more eafily flow that way. I order¬
ed her alfo ten days after, an aloetic purga¬
tive, to dean th z primee vice, that the blood
might find lefs refiftance in its courfie
when determined to the uterus . Next day,
after fhe had taken the purge, I went and
faw
PHYSICAL and LITERARY. 405
faw her, and found it had operated four
times. About feven o’clock that evening,
I applied a comprefs and bandage to the cru¬
ral arteries, at the fame place where they
put the tourniquet in amputations of the
thigh, but not fo tight as to endanger a mor¬
tification of the inferior extremities. At the
fame time, I defired her to fit above the fleam
of warm water. I intended to have flaid
with her, to obferve the gradual effiedts of
the bandage 5 but unluckily was fent for in
a hurry to fee another patient. I left flridl
orders, with a woman who was with her,
to untie the bandage, in cafe fhe complained
of any difficulty of breathing. On my return,
about twenty minutes after, I found her in
the fame fituation I left her in. Her pulfe
indeed beat about fix flrokes in the minute
fafler than before the application of the ban¬
dage. At the expiration of half an hour, fhe
began to feel a fenfe of weight and fullnefs in
the uterine region, and turned fickifli. As
her head and bread: continued pretty eafy, I
begged of her to allow the bandage to con¬
tinue fomewhat longer, and gave her a fpoon-
ful of a cordial-julep. An hour and a half
after the firfl application of the bandage, we
found
406 ESSAYS and OBSERVATIONS
found a vifible appearance of the return of
her menfes , by applying a piece of foft clean
linen to the parts, which, when removed,
was Rained in feveral places. I flacked the
bandage, as her legs were fomewhat be¬
numb’d, but was unwilling to remove it alto¬
gether till the difcharge fhould continue to
flow for fometime. I put her to bed ; and,
on my return next morning, found her ftil!
menftruating and eafy. I now removed the
rollers. The menfes continued to flow for
three days, and returned regularly next pe¬
riod. Since that time, I underftand fhe has
%jeen very healthy.
Art,
PHYSICAL and LITERARY 407
Art. XXXIL
A Dropfy unexpectedly cured ; by Thomas
Livingston Phyjician at Aberdeen^.
AS thofe who are much converfant in the
practice of phyfic and forgery, may
be frequently difappointed in their favour¬
able prognoses, fo they may fometimes be
agreeably furprifed with the unexpected re¬
covery of patients, whofe fymptoms they
had pronounced mortal ; an inftance of
which, I prefume, will plainly appear in the
hiftory of the following cafe.
Robert Duncan, aged about 20 years,
a labouring fervant in the country, was
brought to the Infirmary of Aberdeen "June
19. 1753. He was fo weak, that he could
give no account of the origin or progrefs of
his difeafe 5 but thofe who attended him
from the country informed me, that during
the proceeding winter he had been much ex¬
po fed to cold, after which his belly and lower
extremities began to fwell ; he contracted an
intenfe thirft, with a paucity of urine ; loft
his
* February 6. 1755.
4^8 ESSAYS and OBSERVATIONS
his ftrength and appetite; and the above
fymptoms continued to increafe, without any
means being tried for his recovery. He was
admitted into the Infirmary, not with any
profpedt of relieving his complaints ; but as
he was deftitute, and wanted the common
neceffaries of life, he was ordered a place
on purpofe to let him die in peace. He had
a very large af cites , with an univerfal anafarca ,
particularly of his thighs and legs, which
feemed ready to burft, and gangrenous-like
veficles appeared upon feveral parts of his legs
and feet. His fcrotum was diftended to fuch
an enormous fize, that I could hardly at
firft diftinguifh the penis ; and the above
fymptoms were attended with a dyfpncea and
fuch a defedt of vis vitce, that I could not
difcover a pulfation in any of the arteries,
and was only fenfible of a tremulous fort of
motion about his heart. In this difinal fi~
tuation I gave him over to the care of a
nurfe, ordered him a little warm wine and
water, and expedled to hear of his 'death
next morning ; but I was difappointed.
June 20. His countenance appeared ra-„
tner more lively, ?he fpoke a little with great
difficulty, and I could difcover a very languid
pulfation
Physical and LITE R A R Y. 409
pulfation at his wrifts ; I fniped the veficles
on his feet and legs, and made feveral fmall
pundrares with a common lancet, into the
moft depending parts of the fcrotum ; there
If
was a conliderable difeharge of a bloody-co-
loured ferum from the veficles ; but the dif¬
eharge from the pundures in the jerotum was
clear and pellucid. I ordered warm ftupes
wrung out of a hot aromatic decodion, to
be alternately applied to his fcrotum and legs,
and he got a large fpoonful of th c julap. diu¬
retic. Pharmacop . Paup. every two hours*
with wine and water for his ordinary drink.
2 1 . There was a conliderable
quantity of water difeharged by the pundures
in Jcrofo, the fize of which was fenfibly lef-
fened * but there came nothing from the
veficles on his legs and feet. I made feve~
fal fmall pundures into the calfs of his legs,
and continued the fotus and julep 3 his o-
ther fymptoms much as yefterday.
— -22. 1 here was an incredible quan»
tity of water evacuated from the pundures
in his legs and Jerotum 3 he had more
ftrength, fpoke more diftindly, and his
breathing eafier. Ordered his medicines to
be confined as above.
Vol.IL Fff
23. The
4io ESSAYS and OBSERVATIONS
— - 23. The difcharge from the pun-'
dtures continued as yefterday, the fwelling
of his trunk and extremities was confiderably
diminiflied, his breathing eafier, and pulfe
more diftindt : he had fome appetite : the
fame medicines were continued.
From the 23d to the 26th, the difcharge
continued ; but turned daily lefs, and on
the 27th was intirely flopped ; his head,
thorax , arms, ferotum , thighs and legs, quite
free of fwelling ; but his belly ftill coniider-
ably diftended, tho’ not near fo large as when
he was admitted. He was reduced to the
loweft ebb of weaknefs', and had a light
nourifhing reftorative diet ordered him.
From June 27. to July 4. there was no
very fenfible change on the flze of his belly ;
he ufed the cerevijia diuretica of the Pharma-
cop. Paup. was daily growing ftronger, and
took fmall dofes of rhubarb and pulv. fcillitic .
at fuch intervals as his ftomach could bear
them. • - -
From July 4. to July 20. he continued the
ufe of the cerevijia diuretica , and took three of
the pilul. me r cur. I ax ant. every other nighty
thefe gave him two or three loofe watery
ftools in the morning, w7hich he bore very
well ^
PHYSICAL and LITERARY. 41I
well ) and from the time he began to ufe
them, he paflfed his urine in much greater
quantity than formerly. 1 <
July 25. He was difmifled the Infirmary
quite cured, and continued ftrong and heal-
thy, on the 2 2d of October 1754, when this
was wrote.
Art*
412 ESSAYS AND OBSERVATIONS
Art. XXXIII.
Hiftory of a Patient ajfedled with Periodic
Nephritic Convnlfions > by Cornwell
Tathwell M. D. Phyjician at Stam¬
ford
A Fair healthy looking girl, of a full
habit of body, aged 17, about the be¬
ginning of laft July, without any warning,
fell into violent and general convulfions, and
a ftrong dilirium, which lafted about fix
hours, then ended in Deep, and left a giddi-
neis behind them for fome time. As foon as
the fit was off, £he was blooded and bliftered
by her Apothecary, and feemed to have got
well. In about three weeks after, a diarrhoea
came on, and fhe complained a little of a
a flight pain in her back and bowels ; and
in a month from the firfi: feizure, being a
few days before the' full moon, fhe had a
fecond tit about as long as the former,
which ended in the fame manner. Soon
after this fit, her tongue was of a duiky
colour,
* May 1 , 1755,
t
f
?
PHYSICAL and LITERARY.
413
colour, her pulfe quick, and her urine pale
and fmall in quantity. The blooding was
repeated, a fcetid plaifter applied to the abdo-
domen , and a few ftools procured by pills of
foap and aloes ; after which there appeared
a white fediment in the urine.
Half an ounce of valerian was got down
in faline draughts every day ; in a week, a
feton was put into her neck, and the week
alter Aie began to go into the cold bath
every morning. Some bark and bitters, with
a light chalybeate water, were added to the
valerian, and the opening pills were uled
occaiionally.
About the latter end of Augujl , after fe-
veral ftools, a giddinefs and fleepinefs came
on with a flight delirium, but without any
convulfions.
When fhe was waked out of this deep,
die complained greatly of a pain in her fto-
mach and back ; which neither V. S. the
femicupium , nor tinSlura thebaica, w'ould re¬
lieve for any long time. The next day, on
repeating the femicupium , Hie vomited, and
then nrfr complained of a dyjury : I now
gave her feme pills of foap and fal. martis.
evening after3 the pain returning in
her
414 ESSAYS and OBSERVATIONS
her back and os pubis , fhe was again put
into the Jemicupium , and afterwards voided
a confiderable quantity of pale urine, which
at firft feemed to contain fome rags, but foon
hung with a white cloud, and let fall a whit-
iih powder. The pain going off next day,
the urine was more faturated, and as the
femicupium foon made her faint and lick, it
was omitted.
All this while the catamenia , which had
firft appeared about two years before, were
entirely regular, and generally came on at
their ufual period about a week after each
fit. She now continued the ufe of the pills,
with German Spaw-wat er and the cold bath.
The feton was dried up about the end of
September^ and fhe had only a flight return
of pain in November , which was carried off
by fomenting the abdomen . 1 recommended
lime-water with her pills $ but the has con¬
tinued perfectly well ever ftnce, without
taking any thing.
i. Were not thefe a kind of periodical
nephritic convuljions ? I have known ne¬
phritic fymptoms particularly troublefome
to other female patients about the time of
menftruation a
V*
-PHYSICAL and LITERARY. 4ig
menftruation ; which feems to be owing
to the greater turgefcence of the neigh¬
bouring parts of the uterus at that period,
by which the urinary veffels become at the
fame time fuller and more ftraitened.
2. It is remarkable thefe convulfions
were fcarce accompanied with any fymptom
of the nephritic kind till the pain and dyfury
plainly appeared fo, after the third .fit,
which the intermediate means feem to have
contributed to make much {lighter than the
two former.
This will lead us, efpecially in nervous
cafes, which are often found to be fym-
pathic, to be more particularly attentive to,
even, the fmaller fymptoms, which are
fometimes a better clue to guide us to the
origin of the diforder, than thofe violent ac¬
cidents that are more apt to engrofs our at¬
tention.
8. The diarrhoea proceeding the fits, was
probably only an effect of the irritation of
the urinary paffages by content of parts :
fince the keeping of her open afterwards
feemed of fervice, in (lead of bringing on a
relapfe. Whence I fhall only beg leave to
obferve, how neceffary it is in -practice to
diftinguifh
4i 6 ESSAYS and OBSERVATIONS
diftinguifh fymptoms that only precede o-
thers from thofe that produce others : in
fliort, of what confequence it is not to mif-
take that for a caufe which is only prior in
point of time $ efpecially as this, I fear, is
too common a cafe, and often requires our
titmoft care, in obferving the juvantia and
ladentiay to avoid it.
Art.
%
%
*
PHYSICAL and LITERARY. 417
Art. XXXIV.
** ■ ■ . : ' r - ’ . ". .. ;
Hi/lory of a Fever after Child-bearing-, by
the fame
r . 4 ** •• V A - .1
f ..... A. ■ , . ^ •
A Delicate young woman (who, for two
years before {he was married, had,
from a fright, been fubjecft, at times, to a
kind of hyfteric epilepfy, efpecially at the
approach of the catame?iia ) about four days
after being fafely delivered of her firft child,
had a milk-fever, which came on attended
with languor, catchings and reftiefsnefs. She
was carefully treated with mild diaphoretic
and antifpamodic remedies both internally
and externally. A miliary eruption came out
upon her arms 3 the lochia flowed regularly,
and the belly was kept moderately open :
yet {lie got no reft, was delirious, her tongue
dry and black, and her pulfe quick and
{mail. A blifter was applied over her head,
which, without any pain or ftrangury, pro¬
duced a very large difcharge. The next
day, being the ninth from the beginning of
V°L. II. G g g the
* May 1. 1755.
4 1 8 ESSAYS and OBSERVATIONS
the fever, {he got fome fleep, and became
more fenfible. A gentle perfpiration was
promoted by fp , mindereri in diluents, and
hot bricks applied occafionaily to her feet.
The pulfe was more quiet and regular, the
tongue moifter, and a white cloud fubfided in
the urine. On the 12th day, thefe flatter¬
ing fymptoms vanifhed— the delirium rofe
higher than ever : (he was perpetually co~
matous or convulfed 5 breathed with diffi¬
culty 5 often rubbed her hands together,
and picked the bed-cloaths \ and the pulfe
could fcarce be felt. A ftimulant clyfler
was not retained, veficatbries would not rife
upon her, yet (he was excoriated with in¬
voluntary urine. In this deplorable extre¬
mity, Jinapifms railed a blifter on her feet,
and a large flux was promoted from them
by an emollient cataplafm, to which unguent ,
ad vejicator . was added pro re natd .
As no medicine could be gqt down by the
mouth, pulv. cort. Pcruv. unc. fs. in deccCl .
capit. papav. alb . unc. vi. was thrown up by
way of clyfler, and repeated twice the next
day with fix drams each. Thefe three,
containing in all two ounces of bark, wej-e
retained for a week ; in which time the had
fymptoms
PHYSICAL ANb LITERARY* 419
fymptoms went off by degrees, and die took
freely of both whey and other nourifhment.
Her feet ftill continued running, and were
dreffed with unguent . alb . Three more of
the clyfters with . fcr.up * vi. each were given
in as many days. She now refted well, and
her pulfe was become regular, was much
emaciated, and fo weak, fhe could fcarce be
raifed without bringing on fome hyfteric
fymptoms. By degrees fhe began to recover
her ftrength : the clyfters were repeated
now and then, increafing the quantity of
bark in each to uric . i. Her appetite re¬
turned : in a fortnight die could be got
out of bed : in another week, inftead of the
clyfters, (he took extr. cort . Peruv. fcrup . ii.
twice-a-day,' occafionally interpofing fome
rhubarb 5 in about ten days more die was
got pretty well. The next month die had
a flight fit of the kind die had been ufed
to before marriage ; but, by the help of fome
volatile fetid fimdture in bitter wine, die got
rid of thefe, and has continued free from
them ever fince, tho’ fhe has had feveral
more children.
Art.
420 ESSAYS AND OBSERVATIONS
U ■> ’ •• -r - •
Art. XXXV.
Hijlory of a Fever with bad Symptoms \ by
the fame
A Middle-aged man, generally employ¬
ed in a malt-kiln, about the latter
end of July 1749, fometime after having
fatigued himfelf, and got into a quarrel in
a crowd at a public diverfion, was feized
with a fever ; in the beginning of which,
he was blooded, then had a vomit, and af¬
terwards a great variety of diaphoretic me¬
dicines were tried with him. He was kept
A
fweating, and feveral crops of eruptions fuc-
ceeded each other, without any relief. Bli-
fters were applied in feveral places, yet ftill
a delirium and vigiliee continued. Mufk,
and even the bark in fubftance, was given
him ; but all without any effedl for above
a month. The Apothecary who attended
him in the mean time often urged the necef-
fity of further advice , but his friends would
not confent to it, till, at laft, I was called in.
I
* May n 1755*
PHYSICAL and LITERARY 421
I found him in continual tremors and fubfuU
tus tendinum ; his pulfe was fmall and ob-
fcure, his tongue foul and dufky ; and his
urine had only a flight cloud in it. His eyes
were fo dim, he could fcarce diftinguiffi the
perfons about him ; and it was very difficult
to make him hear, efpecially on the right
fide. He was reftlefs, languid, and deli¬
rious 3 often groaned and fighed, and was ftill
bathed in a perpetual fweat. Some red fpots
appeared upon his bread:, and many purple
and livid ones on his back.
As he had been coftive for fome days, firft
a ftool or two was procured by a warm cly-
fter, fome antimonial drops (which I have
often experienced to deferve very juftly the
encomiums Dr. Huxham * has beflowed upon
them as an excellent deobftruent) were given
now and then in red wine. Elixir of vitriol
and volatile tindlure of bark were admini-
ftred, firft in faline draughts, and afterwards
in tincture of rofes. Within three days, his
fweats were gradually checked, the red pa¬
pula came to a kindly fuppuration, the livid
fpots difappeared, the tremors, fubfultus , and
delirium went off. An abfcefs (which I had
foretold
* Obf, de aere, vol. i. p, 141.
422 ESSAYS AND OBSERVATIONS
foretold from the particular deafnefs on that
fide) broke in his right ear, and, together
with a blifter behind it, was kept conftantly
running. In a day or two more, all the bad
fymptoms were vanifhed ; his pulfe grew
fuller and Stronger, a good fediment appeared
In his urine, and his tongue regained its na¬
tural colour. The volatile tindlure was foon
»
changed for a much larger proportion of the
fimple tincture of bark. In a week, not on¬
ly his fenfes returned, but an appetite ; and
he began to recover his flrength. A ftrong
deco&ion of bark was added to the laft men¬
tioned tinfture, by which, with a few dofes
of rhubarb interpofed occasionally, the cure
was compleated.
Art.
PHYSICAL and LITERARY. 423
* tr* f> • ' 1 ' * ' ; f 1 . • * J ‘ t.
> * . f O- -* • * ' ' - r% r\, ' ♦ t * tj ' • • -1 f . ■ \ { }
-Art; XXXVI. . :
- >; . . . i *. \ . . ' ■ , , 7 ' ;
Accounts of extraordinary Motions of the Wa¬
ters in federal Places of North Britain, and
of a Shock of an Earthquake felt at Dun¬
barton. ... , - L j
ON E great defign of the inftitution of
this Society being faithfully to record
every remarkable phenomenon in nature that
occurs, it has been thought proper to infert
the following accounts of the effects of the
late earthquakes, as they have been obferved
in our diftridt of North Britain ; nor do we
regrete, that they are not more fingular or
interefting in their kind. When all the
fails and circumftances {hall be collected
by the united labours of the learned in dif¬
ferent places, there is reafon to expert, they
may furnifh materials for a more compleat
and accurate hiftpry, than hath been tranf-
mitted of any like event that ever happened
in any. preceedihg age of the world.
That a tremor, which is hardly to be felt
at land, or which may altogether efcape
notice
424 ESSAYS and OBSERVATIONS
notice there, may be very perceptible on
the waters, will eafily be believed 5 nor is
it more incredible, that a fmall concuffion
given to a great body of water will produce
a very remarkable agitation in the narrow
creeks and {hallows. And it is obfervable,
that thefe commotions were mofi violent in
the deepeft lakes, particularly in Loch-nefs 5
the extraordinary depth of which hath been
fometimes affigned as a reafon for its never
freezing, the fevereft winters not being able
to reduce it to the coldnefs of ice.
i. Letter from Mr. Robert Gardiner Com-
mijjary to the Army in North Britain to Dr*
John Stevenson Phyfician in Edinburgh,
giving an Account of the Agitation oj the
Waters of Loch-nefs on the if of Novem¬
ber 1 755, when the City of Lifbon was de-
froyed by an Earthquake.
SIR , ' Edinburgh, December 2 2d 1755.
<c T have your favour of the 20th, and, in
a compliance with your requeft, I give
C£ you the following reply to your queries.—
<c I arrived at F ort- Augufius from Fort-
iC William
>
PHYSICAL and LITERARY. 425
tc William on the 31ft of QBober laft. Next
cc morning about ten, I walked abroad, when
€c the Barrack-Mafter and feveral others came
<e and acquainted me, that they had feen a
<c very extraordinary agitation in the waters
<c of Loch-nefs. I refufed giving credit to their
tc ftory, and a little afterwards returned to
<c the Fort.
cc About eleven, my Clerk and the Brewer
5C at that place came and acquainted me, that
“ a more extraordinary agitation than the
u former had happened, and they apprehend-
€C ed fome danger to our brewery, which is
cc fituated where the river Oich difcharges it*
€c felf into the lake. I walked then to that
€C place ; but before my arrival, the water had
tc returned to its ufual channel. I faw very
££ clearly the marks on the banks, to which
c< it had flowed. The banks were quite wet,
££ and a ftrip of leaves of trees and twigs,
sc &c. left on them. I inquired then into
££ this affair, and the account the fpefta-
<c tors gave, were ; That they obferved
C£ the river Oich , which runs from weft
<£ into the head of the lake, fwell very
cc much, and flow up the river from the
Vol. II. H h h ££ lake
426' ESSAYS and OBSERVATIONS
sc lake with a pretty high wave, about 2 or
<c 3 feet higher than the ordinary furface,
cc with a pretty quick motion againft. the
wind, and a rapid ftream about 200 yards
cc up the river ; then broke on a fhallow,
ce and flowed about 3 or 4 feet upon the
€C banks on the north-fide of the river, and
C£ returned again gently to the lake : That
it continued ebbing and flowing in that
£c manner, for about an hour, without any
waves fo remarkable as the firft, till about
££ eleven o’clock, when a wave higher than
fiC any of the reft came up the river ; and,
i€ to the great furprize of all the fpedators,
broke with fo much force on the low
€C ground on the north fide of the river, as
to run upon the grafs 30 feet from the ri-
£C ver’s bank.
£C Lieutenant Smith of the artillery,
£C Mr. Gwyn fun of Captain Gwyn of the Loch-
se nefs-galley, Mr. Lumjden Barrack-mafter
sc at Fort-Augujius , Mr. Forhes Barrack-ma-
a fter at Berner a , Fhomas Bober tf on Brewer
cc at Fort -Augu jius , and George Bayne my
cc Clerk, and feveral others, were the fpeda-
S£ tors of this extraordinary phenomenon ;
<c fome
PHYSICAL and LITERARY. 427
1 s > » y 1 -
** fome of them favv the whole progrefs of it,
« - ♦ r f
cc others only a part.
*c Loch-nefs is about 20 miles in length, and
from 1 to 14 miles broad, and bears from
cc fouth-weft to north-eaft There wai
M no extraordinary muddinefs in the water,
“ tho' it did not appear quite fo clear as
fC ufual. The morning was cold and gloomy,
and a pretty brifk gale Mowed from
C£ weft fouth-weft. The river Oich lies on
<£ the north fide, of the Fort, and on the
cc fouth fide, runs the river Faff from weft
V. fouth-weft, and difcharges itfelf into the
cc head of the lake, which was obferved to
£C be quite agitated at the fame time and
cc manner as the other. But there was no
“ fhaking or tremor felt upon the land.
1 1 0 . .. . -'■* ’ L
Z . Letter from Lieutenant Isaac Barre to
David Ross, Efq ; Sheriff -Depute of the
Shire of Banff, concerning the Motion
of the Waters of Loch-nefs, November 1.
1 755- - ' 1
SIR , Fort-Augustus, January 15. 1756.
“ T Have been here eight days, and, by
cc A the ftridfeft inquiries, have at laft
r I 4 i . "V .'•*
( c
* It lies between the 57th and 58th deg. of northern latitude.
SfcsS ESSAYS and OBSERVATIONS
“ picked up the following account. Per-*
tc haps the whole may be of little confe-
a quence ; or, if it is, may come too late to
<c be of any ufe to the Gentlemen who de-
fired it.
ec About half an hour after ten in the
c£' morning of the ift of November , Loch -
€C nejs was obierved to rife in a moft extra-
“ ordinary manner at FortfAugujhis it rufla-
cc ed with great rapidity above two hundred
*c yards up the river Qich, which runs into
5C the Loch near the Fort ; it lafted by the
<c beft accounts about three minutes : the
■c people of the country, unaccuftomed to
■c fuch an appearance, imagined at firft it
was caufed by a great number of felks
€C rufhing up the Loch, There was no
cc £hock of any fort felt on ftiore, and the
“ air was remarkably clear, and a very mild
“ day, the wind then being wefterly (and
of courfe again ft the ft ream.)
€£ I could get no account of any perfon’s
“ being in a boat on the Loch at the time 5
<£ but what follows has an air of truth, he-
<s caufe the relater is reckoned an honeft
€C man and of great veracity 3 and befides,
h&d told the fame circumftances frequent-
jy
PHYSICAL and LITERARY/ 429
\
cc ly before he could fufpecl that this extra-
<c ordinary phenomenon would be the fubjedt
<c of a ferious inquiry.
£C He went with a boat for wood, from
cc Glen-morrifon to the Old General's Hut on the
<£ oppofite fide ; and, about the time above-
£C mentioned, his boat being near loaded, as
^£ he was coming to it from the hill, he
cc obferved a fudden and violent wave co-
© k. v • J * ‘
££ ming, which drove her feveral yards on
cc the beach, and returning, drew her back
C£ into the Loch ; a fecond came with rather
£c more violence, and pretty near the fame
“ effedt ; a third came with* a much more
£C extraordinary rapidity than either of the
£C former, and with more furprifing eftefts j
u it drove the boat further on the beach,
£C took the wood intirely out of her, broke
£C off the rudder, and left her afhore full of
££ water. At this time there was a gentle
breeze from the weft, and a mild ferene fky.
u This account was given by James Fer~
iC gufon a Miller at Folt-Soy near Glen-Morri -
“Jon, and aifo attefted by his companion
6£ James Macdonald '.
££ They afiert, that the water, in their c-
pinion, upon examining the ground after-
C£ wards.
430 ESSAYS and OBSERVATIONS
tc wards, mu ft have rifen at leaft three feet
perpendicular ; and the time of the whole
cc agitation was about three minutes.
• ^ ' '■ - * - - ' • 'mn ■ , ' 3
*. - ■ - *. • f - * '• ~ - * i. J * V 9 4 . . '
3. Letter from Mr. John Robertson to
James Smollet of Bonhill, Efq> one of
the Commif aries of Edinburgh, concerning
the Agitation of the waters of Loch-lomonds
November 1. 1755
10. ■ J X M ■*» » • - * ■ **• * • *• " ' '''
. S 1 R, Rosdoe, December 17. 1775a
€? ^ have ^cen from home for a fort¬
night paft, your’s came to hand only
£C yefterday, or would have anfwered it
C£ fooner. The talk you impofe upon me,
€C viz. the' giving an account of the com mo-
<c tion that was obferved in the waters of
Loch-lomond on the ift of November, is al-
£C ready executed, by Mr. Macfarlane the Mi-
sc nifter of Arrochar> according to the heft
accounts he could get of it from the fpe-
sc dlators ; as I was not an eye-witnefs of
€C this uncommon phenomenon, and as the ac~
C( count he gives of it is perfectly agreeable
4£ to the relations of all thofe who faw it.
* hochlomond lies upwards of fifty Engli/h miles weft of
tfrditiburgh, about the 56th degree of north latitude.
PHYSICAL and LITERARY. A*t
££ I will write you an exa£t copy of his re-
" lation, which, I think, is as full and dif-
“ find! an account as can. be got of it.
“ On the ill; day of November laft, Locb-
lomond , all of a fudden, and without any
“ guft of wind, rofe againft its banks with
“ great rapidity, and immediately retired ;
“ an(3 in five minutes time fubfided, till it
t£ was as low in appearance as any body then
££ prefent had ever feen it in time of the
££ greatefi: fummer drought, and then it in-
£t ftantly returned toward the fiiore, and in
££ five minutes time rofe as high as it was
££ before ; and the agitation continued at
££ this rate from half an hour part nine fore-
,£ noon till fifteen minutes paft ten, taking
£C five minutes to rife and as many to fub-
££ fide ; and from fifteen minutes after ten,
££ till eleven, every rife came fomewhat fhort
££ in height of the immediately preceeding
££ rife, taking five minutes to flow,' and five
tc to ebb, until the water fettled as it was
££ before the agitation. After the agitation
££ was over, the height to which the water
££ had rofe was mealured, and found to be
££ 2 feet 4 inches perpendicular. Loch-long
“ and Loch-keatrin were agitated on the fame
££ day
432- ESSAYS and OBSERVATIONS
cc day, and about the fame time ; but the
tc phenomenon was not fo minutely obferved
ec as that any exad account can be got of it.
u This relation of Mr. Mac f aricine s of the
€C phenomenon , contains in it every thing re~
ec markable I have as yet heard concern-
ing it.
4. Letter from Mr. Mark McCallum to
George Clerk, Efq, concerning an un -*
ufual motion of the Waters of the Frith of
Forth at Queens-ferry, [even miles weft of
Edinburgh, on the if of November 1755.
SIR,
#c rjpo the beft of my remembrance, on
Saturday the fir ft of November , a~
bout ten o’clock before noon, being then
€C on the pier at Queens- Ferry, I obferved the
water to rife very fuddenly, and return
cc again with the fame velocity about a
€C foot or eighteen inches perpendicular,
cc near as I can remember ; the barks and
“ boats then afloat ran forwards and back-
<c wards with great rapidity, and this conti-
“ lined for the fpace of three or four mi-
tl nutes 5 but after the fecond or third rufti
{C of
PHYSICAL and LITERARY 433
cc of the water, it gradually abated. There
“ was no wind at the time the waters were
£C agitated as above;5
r~ * ' * * «■ r
< '■ N
5. yf/z Account of an unufual Motion in the
r
Waters of Clofeburn-L^ Dumfries-
Shire , Sunday 1/? February 1756*
zVz ^ Ltfter to George Clerk/ Efq-y
SIR, Closeburn, February 4. 1756.
SC ^\BOUT a ^uarter before n^ne on Sunday
<£ morning, we were alarmed with an
tc unufual motion in the waters of Clcfeburn -
“ Loch. The firft thing that appeared to
“ me in this wonderful fcene, was a ftrong
“ convulfion and agitation of the waters from
“ the weft fide towards the middle, where
tc they tolled and wheeled in a terrible man-
<c ner. From thence proceeded two large
£< currents, or more properly rivers, which
tc ran with a fwiftnefs and rapidity beyond
cc all defcription quite contrary ways ; one
<c from the middle to the fouth-eaft, and
Vol. II. I i i “ the
* It may not be amifs to obferve, that, on the ift of
February 1756, according to advices from abroad, a cor»ii-
derable earthquake happened at Oporto in Portugal .
434 ESSAYS and OBSERVATIONS
<c the other to the north-eaft points of the
sc Loch. There they were flopped fhort,
cc as the banks are pretty high, and ob-
tc liged to turn ; which occafioned a pro-
** digious tumbling and agitation at both
<£ ends of this body of water. There was
cc likeways a current which rofe fome-
“ times confiderably above the furface, near
<c the weft fide, that I frequently obfer-
c& ved running with great velocity a hun-
<c dred yards to the fouthward, and re~
cc turning in a moment with as great ve-
“ locity the other way. What I obferved
<c in the next place, was the tolling of
<c the waters in the ponds, which were
<c more or lefs moved as the agitation of
Ci the Loch came near this fide, or kept
C£ at a greater diftance from it. But, as
££ it is beyond my capacity to give a particu-
<c lar defcription of all that happened on this
£€ occafion, I (hall conclude with telling you,
£C that the agitations and currents above men-
€£ tioned continued, without intermifiion, for
S£ at leaft three hours and an half, or four
• -* , •* *
<c hours, when they began to abate a little in
£s their violence, tho’ the tofiings and cur-
<e rents were not quite over at funfet. I had
“ almoft
PHYSICAL and LITERARY. 435
€< almoft forgot to tell you, that this 'phano-
“ menon was renewed on Monday morning a
little before nine, and lafted for an hour
and an half ; but the motion of the waters,
“ &c . were not fo violent as the day before.
What is very remarkable, there was not
cc the lead: gale of wind on Sunday till one
o’clock, which helped us not a little in our
<c obfervations/’
v6. Letter from Mr. Pan ton relating to the
Earthquake felt at Dunbarton.
SIR , Dunbarton, January 17. 1756.
quake here, there happened but one
cc fhock, and that very moderate, before one
<c of the clock December 31ft 1755 ; it con»
<c tinued for a very fmall fpace of time. It
cc agitated fome people in bed very percepti-
cc bly, and was felt by Mrs. Weir and fome
€C others, who were not gone to bed. It
“ had a fenfible effedt upon tame birds in
tc cages, and fowls : it fo alarmed both, as
C£ to make the former flutter prodigioully,
<c and the latter to croak in a frightful man-
ner : it fhook the board out of one cage,
“ and
43 6 ESSAYS and OBSERVATIONS
ct sftid fpilt the water in the glafs thereof. It
cc was equally felt by thofe who lived in
ce ground-ftoreys, as by thofe in fecond and
cc third ftoreys. There were fome fconces
cc in Mrs. Colquhoun s houfe obferved to vi-
u brate during the fhock. Nothing more
cc happened worth noticing.
N. B. This earthquake was felt at the fame
time in Glafgow , Greenock , and other places
of the neighbouring country.
End of the fecond Volume .
V
Acids, their attradion of fixed akalis, calcarious earths, &e,
pag. 224.
• - quantity of air expelled from aicalis by them, 177.
Air (fixed) attracted by calcarious earth, fixed alcali, £3 fc. 224,
Air> the reparation of it from calcarious earths, turns them fc.
to quick-lime, 185.
Air, chalk deprived of it, affords lime-water, 206.
Air-pump, the cold produced in its exhaufled receiver, 153.
Aicalis, the quantity of air expelled from them by acids, 177.
Alcali (cauftic) contains no lime, 192. and 200.
Alcaline fubftances, experiments on them, 157.
Antimonial wine, an uncommon effed of it, 254.
Ani [procidentia) remarks on it, 353.
B.
Belly, a child efcaping by a rent in it, 340.
.Black (Dr. Joseph) his experiments on magnefia alba , quick¬
lime, &c. 157.
Bodies, the reflexion of light from their furfaces, 84.
- - light ones their fpontaneous motions on the furfaces of
fluids, 26.
■ - — coloured ones, the changes they undergo in different -
lights, 32.
■ - - doubts, difficulties, and conjedures con¬
cerning them, 59.
Bones, drawings of very large ones, 11.
Boswell (Dr. John) his account of bones found in the ova¬
rium of a woman, 273.
Bulge-water tree, its bark cures worms, 264.
C,
INDEX,
c.
Cataraft, obfervations on the new method of curing it, 324,
Chalk, deprived of its air, becomes lime, 206.
Chryftalline humour, extracted fuccefsfully after the new
method, 327, &c.
Clerk (George Efq;) his drawings of very large bones, 11.
Clouds, their various colours at fun-rifing and fun-futting ac¬
counted for, 75.
Closeeurn (Loch) an uncommon motion of its waters, 433.
Colden (Mifs Jenny) her defcription of the Gardenia , a new
plant, 5.
C$ld, produced by evaporating', fluids, and by other means, 145.
Colewort, of the filver-like appearance of the drops of water
• 1
on its leaves, 25.
Colours, obfervations on them, 12.
- - queries, doubts, and conje&ures concerning them, 59.
Convulfions, periodic nephritic ones, 412.
Concretions, hiftories of tophaceous ones in the alimentary
canal, 345.
Cows, large balls found in their flomachs, 351.
Cullen (Dr. William) of the cold produced by evaporating
fluids, and by other means, 145.
D.
Dogs, experiments made on them with opium, 297.
Dropfy, a hiftory of one cured unexpedtedly, 4^7*
Dyfentery, an obftinate one cured by lime-water, 257.
Duguid (Peter) on the anthelminitic virtue of the bark of
the bulge- water tree, 264.
Dunbarton , an account of an earthquake felt there, . 435-
E.
Earth, calcarious, its relation to air and water, 188.
_ _ .when deprived of its air, is converted into quick¬
lime, 185.
Earthquake, one felt at Dunbarton , 435.
Euler*
I N D E X.
Euler, a miftake of his, 17.
• — - a remark on his no<va theoria lucis , &c. 36,
Evaporation of fluids, produces cold, 145.
% ^ *■
F.
Fell (Stephen) his hiftory of a preternatural colle&ion of
water with twins, 342.
Fever, after child-bearing, 417.
- with bad fymptoms, 420.
Fever ( American yellow) a description of it, 372'.
— - - its fymptoms, 376.
• - its prognofls, 391.
Fluids, the Spontaneous motions of light bodies on their fur-
faces, 26.
» — - the cold produced by the evaporation of different
ones, 1 49.
Focus, of a fpeculum , not heated by the paflage of light
thro1 it, 22.
Foetus, a defcription of a monftrous one, 226.
Frogs, experiments on them with opium, 281*
r • " . - . •
* G.
G arden (Dr. Alexander) his description of a new plant, 7.
Gilchrist (Dr. Ebenezer) his anfwer to an obje&icn a-
gainft inoculation, 396.
Gout in the ftomach, cured by muik, 250.
Guts, remarks on their intufufceptio and inflammation, 333.
Grainger (Dr. James) his account of a dyfentery cured by
lime-water, 257.
H.
Haller (Dr. Albert) a miftake of his, 306.
H amilton (Dr. Archibald) his account of the effefls of
femen hyofcyami, 243. ,
— — - his propofal for curing obftru&ed menfes , 403.
Heart, its power of motion deftroyed by opium, 306.
_ — in
IN D E X.
»- . — in frogs becomes fhorter and paler during its fyfiole , and
longer and redder in its diaftole , 290.
Henbane, feed, its eftedls when taken in a large dofe, 243.
Hernia , a hiftory of one, 333.
. ■ I.
Inoculation (of the fmall-pox) an objedlion againft it anfwered^
396. , '
• - •* — - —the moll proper time for it, 401.
Intufufceptio of the guts, remarks on it, 359.
Inflammation of the guts, remarks on it, 365,
K.
t hr \ ■ ' -
Kepler’s problem, a folution of it, 105*
L.
Light, obfervations on it, 12.
— - -its mutual penetration, ibid.
- - — its amazing fubtility, 13, &c .
- - -on the heating of bodies by it, 1 8.
- — - its reflexion from t;he furfaces of bodies, 84.
- its rays projected with different velocities, 41.
_ _ -the caufe of the different refrangibility of its rays, 4c?.
. - the imperfection of oar knowledge concerning its in¬
flexions, 54.
- - queries, doubts, and conje&ures about it, 59.
Lights, different ones produce many changes in coloured bo¬
dies, 31.
Lime-water procured from chalk without calcination, 206.
■ - — cures the dyfentery, 257,
Lind (Alexander. Efq;) on the analyfls and ufes of peat,
226.
Lining (Dr. John) his hiflory of the American yellow fever,
Livingston (Dr. Thomas) his hiflory of zhernia, 333.
■n . . — his account of a dropfy, 407.
ttoch-fatnond
I N D- E X.
Loxh-lomond and Lach-nefs , an unufual agitation of their wa¬
ters, 424. and 430.
Lungs, always contiguous to the pleura, 2 76.
Luxation, a compleat one of the thigh, 317.
• • M.
Mackenzie (Dr. James) his hiftory of a compleat luxation
of the thigh, 317.
Magnefia alba, experiments on it, 157.
- - - its hiflory and medical virtues, 138. &c.
• - it deftroys quick-lime and lime-water, 170.
- — - cannot be reduced by calcination to quick lime,
172.
— - the quantity of air expelled from it by acids,
1 78.
Melvill (Thomas) his obfervations on light and colours, 12.
Menfes , a new method of curing an obftru&ion of them, 403.
Moon, an eafy method of computing its parallaxes, 91.
Monro (Dr. Alexander fenior) his proofs of the contiguity
of the lungs and pleura, 276.
- - * - his hiftory of a child efcaping by a rent in the
womb, 341.
— ■ — - his hiftory of tophaceous concretions in the ali¬
mentary canal, 345.
* — - his obfervations on procidentia: ani, intufufcepiio ,
and inflammation of the inteftines, 333.
Monro (Dr. Alexander junior) his difledion of a mon-
ftrous fcetus, 270.
— _ - his account of a true volvulus of the inteftines. t68.
Mowat (James) his defcription of a monftrous fcetus, 266.
Mulk, cures the gout in the ftomach, 230.
N.
Needle, a fmooth one does not touch the furface of the water
on which fwims, 30.
K k k
New ton
*
INDEX*
5
Newton (Sir Isaac) miftaken in his conjedlure concerning
the colours of the clouds at fun-rifing and fun-fetting, 75,
Nephritic convulfions, 412.
O.
Opium , experiments made with it on animals, 280.
» — • .. deftroys all feeling and power of motion in animals, 301,
— - - does not produce its effedts by comprelfing the brain or
bringing on deep, 313.
— - its effedts, not owing to any fubtile effluvia fent to the
brain or mufcles, but folely to its adtion on the nerves to
which it is applied, 302. and 308.
- - kills frogs fooner than the deftrudtion of their brain and
fpinal marrow, 304.
* - kills dogs fooneft when injedted into the cavity of their
abdomen , 306.
- — — - deftroys the irritable power of the mufcles, 310.
- — - retards and at laft puts a ftop to the motion of the
heart, 305.
— — - the way in which it kills animals, 314.
Ovarium, of a woman, bones found in it, 273.
1 -»
P.
Parallaxesof the moon, an eafy method of computing them, 91.
Peat, its analyfts, 226.
•t* - its ufes, 231.
Philofopers, a miftake of many of them, 22.
Planets, why they appear white, 72,
Plant, a defcription of a new one, I.
Pringle (James Efq;) on the effedts of mulk in the gout in
the ftomach, 250.
Procidentia, ani , remarks on its cure, 354.
Q. '
Quantity, its endlefs divifibility aiferted againff fome Sceptics, 71,.
Queries concerning light, colours, and coloured bodies, 59.
Quicjk-
I N D . E X
Quick lime, experiments on it, 157.
. - only an acrid earth deprived of its air, 187.
„ _ produced without the afiiftance of fire, 206.
1 - — — deftroyed by magnefia alba> 1 7 * •
Queens-ferry , an unufual motion of the waters there, 432.
R.
Rays of light, the caufe of their different refrangibility, 4©o
_ differently colon-red ones proje&ed with different ve¬
locities, 41.
\ » _ . , j j. \j A w . . . ; . / * . *. 1 x a * f
S.
* ... , * * v
Salts, different ones mixed with fpirit of wine, grve different
lights, 32. “ * • *
Sceptics, an objection of theirs againfl the endlefs divifibility
of quantity anfwered, 71.
Sky, its bluenefs accounted for, 73.
Soap-ley, contains no lime, 192. and 200.
St ewart (Matthew) his folution of Kep he r'-s problem, J 105.
Stramonium , the effe&s of its fruit, 247.
Swaine (Dr. Abraham) on the effects of the thorn-apple, 247c
T.
Tathwell (Dr, Cornwell) his hiftory of periodic nephri¬
tic convulfions, 412.
- - - hiftory of a fever after child-bearing, 4.17.
— - 'hiftory of a fever with bad fymptoms, 420,
Teeth found in th z ovarium of a woman, 273.
Thigh, a compleat luxation of it, 317.
Thorn-apple, its effe&s, 247.
Tree (wild cabbage) its bark cures worms, 264.
Twins, with a preternatural collection of water, 342.
V.
Vis fercujjtonis , a luxation of the thigh cured by its means, 317.
Volvulus of the inteftines, an account of a true one, 36$.
INDEX.
w.
Walker (Dr. James) his account of an uncommon effect of
antimonial wine, 254.
Water, of the filver-like appearance of its drops on the leaves
of cole wort, *25.
Waters a preternatural collection of them with twins, 342.
•—in feveral places of North Britain , an uncommon mo¬
tion in them, 423.
Womb, a child efcaping by a rent in it, 341.
Worms, cured by the bark of the cabbage-tree, 264.
Whytt (Dr. Robert) his defcription of the matrix of the
buccinum am^ullatum, 8. 0
— — - his experiments with opium, on living and dying
animals, 280,
Y.
Yellow fever (of America ) its hiftory, 370.
Young (Thomas) on the new method of extracting the
cryftalline lens, 324.
To the BOOKBINDER.
Place Tab. I. fronting pag. 10
— - - II. __ ~ 1 z
— - — III. - 9°
— - IV. - — 104
- — V. - - *44
- VI. - - 276
- - — VII. - — - 364
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