53 
INJECTION, 
fee perilfted in for ten or twelve days after the running 
has ceafed. 
The word injcftion is alfo ufed for the throwing in tome 
liquor or medicine into a vein opened by incifion. This 
practice, and that of transfufion , or the conveying the ar¬ 
terial blood of one man, or other animal, into another, 
■were once greatly praCtifed, but are now laid afide. See 
Transfusion. 
Anatomical Injection, the filling the veffels of a human 
or other animal body, with tome coloured fubftance, in 
order to make their figures and ramifications vifible. 
The inftrument with which the liquor is commonly 
thrown into the veffels is a tight, eafy-going fyringe of 
brats, to which feveral fliort pipes are fitted, and can 
be fixed by ficrews, the other extremities of thefe pipes 
being of different diameters without any fcrew, that they 
may Hide into other pipes, which are to exactly adapted to 
them at one end, that, when they are prefled a little toge¬ 
ther, nothing can pafs between them : and becaufe their 
cohefion is not fo great as to refill the pulhing force of 
the injeCtion, which would drive off this fecond pipe, and 
i'poil the whole operation; therefore the extremity ot this 
fecond fort of pipes, which receives the firft kind, is form¬ 
ed on the outfide into a fquare, bounded behind and be¬ 
fore by a riling circle, which hinders the key that clofely 
grafps the fquare part from Hiding backwards or for¬ 
wards ; or a bar of brafs mull Hand out from each fide of 
it to be held with the fingers. The other extremity of 
each of thefe fecond fort of pipes is of different diame¬ 
ter; and near it a circular notch, capable of allowing a 
thread to be funk into it, is formed ; by this, the thread 
tying the veffel at which the injection is to be made, 
will not be allowed to llide off. 
- Befides this form defcribed, common to all this fecond 
fort of pipes, we ought to have fome of the larger ones, 
with an additional mechanilm, for particular purpofes; 
as, for inftance, when the larger veffels are injeCted, the 
pipe faftened into the veffel ought either to have a valve 
or a ftop-cock, that may be turned at pleafure, to hinder 
any thing from getting out from the veffel by the pipe; 
otherwife, as the injection, in fuch a cafe, takes time to 
coagulate, the people employed in making the injeCtion 
muft either continue all that while in the fame pollute; 
or, if the fyringe is too foon taken off, the injeCted liquor 
runs out, and the larger veffels are emptied. When the 
fyringe is not large enough to hold at once all the liquor 
neceffary to fill the veffels, there is a necefiity of filling it 
again. If, in order to do this, the fyringe was to be taken 
oft' from the pipe fixed in the veffel, fome of the injection 
would be loft, and what was expofed to the air would cool 
and harden'; therefore fome of the pipes ought to have a 
reflected curve tube coming out of their fide, with a valve 
fo difpofed, that no liquor can come from the ftraight 
pipe into the crooked one, but, on the contrary, may be 
allowed to pafs from the crooked to the ftraight one; the 
injector then, taking care to keep the extremity of the re¬ 
flected pipe immerfed in the liquor to be injeCted, may, 
as foon as he has pufhed out the firft fyringeful, fill it 
again by only drawing back the fucker; and, repeating 
this quickly, will be able to throw feveral fyringefuls 
into the veffels. All thefe different forts of pipes are 
commonly made of brafs. 
Very great improvements have been made in anatomy 
by means of injections. Ruylch firft employed them with 
fuccefs: and it is faid that the czar Peter; feeing an in¬ 
jected boy, whofe appearance nearly refembled life, ran 
and killed it. 
Injections, which unite with water, and confequently 
with the animal fluids, confift of ifinglafs and common 
lue. Thefe fucceed with the finer veffels, in membranes ; 
ut, if employed to fill the larger, they take too long time 
in coagulating. If coagulated by alcohol, they become 
brittle; and, when the water is carried off by evapora¬ 
tion, the velfels-are not properly filled. It has been at¬ 
tempted to remove thefe inconveniences, by firft injeCling 
VOL, XI. No. 733- 
the folution of glue ; and, when the capillary veffels are 
filled, a coarfer wax injection ; but the wax either hardens 
too foon, mixes irregularly with glue, or the parts fepa- 
rate where the two fluids are in contaCt. Alcohol mixes- 
both with water and oil, and confequently has been em¬ 
ployed to fill the capillary veffels, but it coagulates the 
animal fluids it meets, and often blocks up the canal. It 
will not fufpend durably-coloured pow ders, and at lalt 
evaporates, leaving little more than the colours of thofe 
to which it had been united. Melted tallow', with a lit¬ 
tle mixture of oil, is often ufeful; but it fometimes flops 
too foon, where it meets with animal.fluids, and becomes, 
by time, very brittle. Oil of turpentine, recommended 
by Dr. Monro, is generally employed to fill the finei vef¬ 
fels. It fufpends the colouring matter; and, when the 
more volatile parts are evaporated, enough of the groffer 
particles remain, to retain the powder, and keep the vef¬ 
fels fufficiently full. After this is injeCted, it is confined 
by filling the larger veffels with a. coarfer, injeCtion, with, 
which it unites very accurately. 
Anatornifts have preferred for the colour of their injec¬ 
tions fuch pigments as moft nearly imitate the natural 
contents of the veffels; the red for the arteries, and the 
blue for the veins. The vegetable colours are apt to con¬ 
crete, and are deftroyed by infers. The mineral are 
therefore preferred. The red is generally vermilio-n, a 
fubftance which in a fmall proportion gives a very confi- 
derable body of colour; and the green confifts of diftilled 
verdigrife, which is brighter than the common fort, and 
diffolves in oil; the blue of verditer or fmalt; the yellow 
of king’s yellow ; the black of lamp r black or burnt ivory 
are ufed. The properties required in the injecting mat¬ 
ter are fluidity ; and they muft likewife grow ftiff, but 
tough and flexible when cold ; for, were they too hard, 
the fmaller veffels would be frequently broken. The fol¬ 
lowing, recommended by Dr. Nichols, feem to poffefs thefe 
properties : Fine Injeclion. Take hard white Spanifli var- 
nifh, and hard browm Spanifli varnifh, of each equal parts j 
turpentine varnifh, and vermilion, of each a fufticient 
quantity. Mix them. Coarfe Injeclion. Take of yellow 
refill two pounds ; of yellow wax one pound ; of turpen¬ 
tine varnifh a fufficient quantity. Thefe injections may 
be coloured with vermilion or with verdigrife. What¬ 
ever colouring matter is ufed, it muft be ground ex¬ 
tremely fine. 
Dr. Monro recommends for the fine injection a pound 
of oil of turpentine, gradually poured on the colouring 
matter finely powdered. To procure the vermilion or 
verdigrife very fine, it may be agitated with the oil; and, 
after Handing at reft a little time, poured off; the coarfer 
parts will by that means be feparated, as they will have 
lubfided. Dr. Monro’s coarfer injeclion confifts of tallow 
one pound, white wax five ounces, common oil three 
ounces, melted over a lamp, adding Venice turpentine 
two ounces. When this is diflolved, the whole muft be 
ftrained through a warm linen cloth ; and, if defigned to 
run far, fome oil of turpentine muft be added when it is 
ufed. The fine injections, it is faid, fhould be thrown in 
as warm as the finger can well bear; the coarfer nearly aj; 
the boiling point. In general, however, thefe directions 
are erroneous ; for; by fuch beats, the colour will be 
changed, and the coats of the veffels injured. It will be 
faferto give them only fo great a degree of heat as is fuf¬ 
ficient to render them perfectly fluid. 
Quickfilver is frequently uied for injections, and it is 
excellently adapted for this purpofe, from its admitting 
of the minuteft divifion. Were it poflible to render it 
folid, and to impart to it any given colour, its advantages 
would be very confiderabie. May it not be poflible to 
oxydate it within the veffels ? Its great fluidity is, how ¬ 
ever, inconvenient, as the flighteft .punCture empties all 
the veffels filled with it; and its weight renders the pre¬ 
paration fo heavy, that it is liable to ftrike againfc the 
glafs, and to rupture the diftended veffels. In injeCling 
with quickfilver no impulfe of a pifton is neceffary, for 
