CHEMISTRY. 
374 
into vapours, came over in this Form into the receiver, 
together with the other gas, where it condenl'ed, and 
maintained the gas in folution. This was the mode of 
proceeding in the operations above-mentioned; but this 
method is liable to many objedtions and inconveniencies, 
the principal of which we will flate. 
1. Many aeriform acids, ammoniac, &c. are much more 
volatile than water, and come over, for this reafon, in 
part, much fooner into the receive)' than the water. The 
dirfl: portion of thofe bodies, not being arrelted by the 
water, is, therefore, loft. Chemills endeavoured to ob¬ 
viate this fault, by making ufe of very large receivers, in 
which the gas remained included, till it could be dif- 
■folved in the water as it came over. But even thefe were 
infufficient, ar.d required to be tubulated to procure an 
jfifue for the accumulated gas, and prevent the apparatus 
from breaking. Sometimes, alio, the experimenter ufed 
to introduce a ftnall quantity of water into the receiver, 
previous to the operation ; but, as the gas only touches 
the furface of tire water, its folution became extremely 
tedious- 
2. It has been proved that gafeous bodies are difl'olved 
much more readily and copioully in cold than in hot 
water. Now, as the water which comes over during the 
above procefs is always hot, it heats the receiver, and, 
•of courle, remains hot for a long time; this is confe- 
-quently a new impediment, and the water cannot, there- 
ffore, in this manner, be perfedtly faturated with the gas. 
3. From what has been obferved, it follows, that the 
dofs experienced during thefe operations can be dimi- 
nilhed only by an extremely flow and careful operation, 
and that the flighted: inattention may not only fpoil the 
whole procefs, but endanger the life of the operator. But, 
notwithftanding the utmoft precaution and attention, the 
operator remains expofed, in a great meafure, to the nox¬ 
ious and difagreeable vapours; even the mere effufion of 
fuming fpirit of nitre, and of concentrated muriatic acid, 
from the enormous receivers, is attended with great in¬ 
convenience. 
4. If, efpecially in operations in the large way, any 
dirt or impurity adhered to the body made ufe of, it was 
taken up by the water, and came over into the diflilled 
liquor, for which reafon the fuming and concentrated mu¬ 
riatic acid, for in dance, was never obtained clear. 
5. Neither the quantity, nor the degree of concentra¬ 
tion of the liquor to be obtained, could be optionally de¬ 
termined, fince the lofs depended upon a great many cir- 
cumflances, which the operator could not altogether fore¬ 
fee nor prevent. 
To obviate.thefe inconveniencies, feveral chemills pro- 
.pofed new machines, for the purpofes of dillillation ; but 
none have been more generally approved, than that of 
Mr. Peter Woulfe, which, w : ith the improvements by 
Pelletier, we fhall defcribe, as follows: 
WOULFE’S APPARATUS. 
This apparatus, as ufed in chemical and pharmaceutical 
operations, is always formed of glafs, and, which is the bell, 
of white glafs. In large manufadlories only, it may, ac¬ 
cording to circumllances, be partly made of wood, iron, 
copper, See. The peculiar velfels and inftruments of 
which it is -compofed, are delineated in the Chemiftry 
Plate VI. Fig. 1, is the apparatus, with luted junctures, 
for the reception of gafeous and liquid bodies. Fig. a, 
is the apparatus for the dillillation of fuch bodies as come 
over in the form of gas only, with refrigeratory veflels, 
and junctures not luted. 
Fig. 5, the tubulated receiver, or balloon with two 
.necks. This receiver ought to have a Ihort wide neck, 
proportioned to the beak of the retort intended to be 
ufed. It Ihould alfo be rather wider towards the mouth, 
and conical towards the receiver, that it may be joined 
^the clofer to the beak of the retort, and be more firmly 
.luted. As moll of the common receivers are jars, of 
•which the greateft part of the neck is broken off, they 
have the fault that their neck is narrow at the mouth, 
and wider towards the belly. The collateral neck of 
this receiver Ihould be very round, and fufticiently long, 
that a cork of fome length may exadlly fit in it. More¬ 
over, the polition of this neck ought to be fuch, that, 
when the receiver is connected with a retort moderately 
inclined, it Hands perpendicularly, as fhewn at fig. 1. 
The dimenfion of thefe receivers ought to correfpond 
with the extent of the procefs; in chemical or pharma¬ 
ceutical experiments, we have feldom occafion for larger 
ones than fuch as hold from eight to twenty pints. If 
the receiver be very lmall, the collateral neck may be 
omitted; but, inflead of it, we Ihould bore a hole, of 
about two lines in diameter, to admit the communicating 
tube. 
Fig. 3, and 4, are Woulfe’s bottles. Thefe are com¬ 
mon cylindrical fhort-necked bottles, furnifhed, befides 
the ufual neck in the middle, with one or two collateral 
necks. At firft they made ufe alfo of bottles with four 
necks, but thefe may be difpenfed with in almolt all ope¬ 
rations, for thofe with two and three necks, anfwers all 
purpofes as well. The middle or principal neck of thefe 
bottles is generally fomewhat wider than the reft; but 
its diameter Ihould never exceed one inch, for otherwife 
the junctures become unnecefiarily large. Moreover, 
thefe necks fhould be almoft cylindrical, very round, and 
as much as poflible perpendicular and parallel. The fize 
of thefe bottles differs according to the operation; they 
cannot, however, be much fmaller than of half a pint; 
and, in extenfive operations, they do not require to be 
larger than of twelve pints. 
The communicating tubes conned the apparatus toge¬ 
ther. Of thefe the experimenter fhould have feveral in 
ftore, or he fhould form them, according to neceflity, of 
llraight tubes of foft glafs, which he may bend over a 
charcoal fire, or by the blow-pipe. If the operation be 
moderately great, they are belt of one line in diameter j 
but, in greater operations, they may meafure as much as 
two lines. In general, it is better to have them too wide 
than too narrow. The intermediate part between the 
ends fhould be fufticiently long, that the bottles, with 
which it communicates, as well as the refrigeratory vef- 
fels, may conveniently fland near each other. The cor¬ 
ners or angles of the communicating tube fhould not be 
too fliarp, but fomewhat round, otherwife the tube is li¬ 
able to break. They may be liKewife made in the form 
of a femicircle. They are commonly quite Ample, but in 
fome cafes they are furnifhed with a fhort capillary tube. 
The tube of fafety, is a llraight glafs tube, riling up¬ 
wards, of about one line in diameter, and about two feet 
in length. 
Fig. 6, the adopter; which ferves to combine a retort 
with one of Woulfe’s bottles, as at fig. z. We fhould 
always be furnifhed with feveral of thele, of different di¬ 
menfion, according to the fizes of the different retorts. 
Smaller ones may be made of the beaks of old retorts. 
The refrigeratory veflels ferve to cool the liquids con¬ 
tained in the bottles, by means of ice, fnow, or cold wa¬ 
ter, continually replenifhed. For this purpofe we may 
ufe fmall wooden tubs, earthen batons, &c. But the molt 
convenient veflels are thofe made of copper, or tin, painted 
with oil colours; they bave a cock or fyphon near the 
bottom, by which the melted ice, or the water, when it 
becomes too warm, is drawn off. In thefe veflels the jars 
or bottles are placed, as at fig. 2. 
As the joinings in all operations where Woulfe’s ap¬ 
paratus is employed, fhould be perfedlly doled, left any 
aeriform body pals through, the choice of a proper lute 
is of very great importance. Ail lutes, it is well known, 
are divided into two claffes, into fat and common lutes. 
Of the former we make ufe of two kinds in Wouife’s ap¬ 
paratus, which are prepared in the following manner: 
1. Take very dry rich clay, triturate it in an iron mor¬ 
tar, and form it into a thick pafte, by fucceifively add¬ 
ing boiled linfeed oil, commonly termed linfec-d varnifh. 
This 
