C H E M 
bination without intermixture or difiurbance of other 
bodies not intended to enter the propofed experiments, 
and alfo in raifing or lowering the temperature of fuch 
bodies under examination, it is evident that the degree 
of fuccefs attending thefe refearches mult greatly depend 
upon the veflels or apparatus adapted to that purpofe. 
The inflruments that have from time to time been tiled 
with this intent, are many and various. Modern che- 
miftry however, has rejected feveral which only caul'ed 
trouble and confufion ; for which reafon we (hall coniine 
ourfelves to the deicription of thofe only in prefent ufe, 
Th.e MODERN CHEMICAL APPARATUS. 
The articles which firft prefent themfeives, as being 
immediately requifite, are crucibles or pots, adapted to 
■the purpofes of roafling, calcination, and fufion. The 
moft perfeft of thefe are laid to be made of Groffallme- 
rode and Elltrode in HefTe, manufactured by refraCtory 
clay and fand. Some of them are large and round, fome 
triangular, having Hands and covers. Some are fmaller, 
■called fet-crucibles, becaufe they are of different fizes, and 
fitted into one another like fets of chip-boxes. In lome 
cafes iron and filver crucibles are ufed. Thofe of Ips in 
Upper Auftria, or of Hafnerzell; confifls of black lead 
and fand ; they are made of different fizes, and are very 
■durable under every change from heat to cold ; but im¬ 
proper for melting many ialine fubitances. In the che- 
■xniftry Plate I. is delineated at fig. i, a round crucible, 
with its cover and fl;and ; fig. 2, a triangular crucible, 
on its Hand. For the melting of ores in fraall quantities 
dor docimaflic purpofes, afi'aying crucibles are employed, 
made of the fame materials as the earthen ones. They 
■have, in their inner cavity, the form of a double cone, 
bellying out in the middle, and contrafted at both ends; 
one of thefe is fhewn at fig. 3. The chalice-form cruci¬ 
bles, and the fcorifying tells and capfules, are alfo of 
•this clafs. 
Cucurbits, or matraffes, are glafs, earthen, or metal¬ 
lic veffels, ufually of an ovate or egg fhape, and open at 
the top. They fer.ve the feveral purpofes of digeftion, 
evaporation, folution, &c. Two of thefe are fhewn at 
•fig. 4 and 5, in the plate. That with the ring on its 
meek, at fig. 4, renders it capable of being fufpended by 
a firing. 
Retorts, are globular veffels of earthenware, glafs, or 
Tnetal, with a neck bent on one fide. Some retorts have 
another neck or opening on their upper 'part, through 
which they may be charged, and the opening may be 
afterwards clofed with a Hopper. Thefe are called tubu¬ 
lated retorts; the other Jirnple. The tubulated retort is 
.ufed, when, on account of the two rapid extrication of 
gafes or acids, its neck muH be luted to the receiver or 
balloon, before the materials are introduced, or the fire 
applied. Holes are alfo fometimes drilled on the upper 
•parts of Ample retorts, to let out, by opening their Hop¬ 
pers, the elaftic fluids when too copious. Fig. 6, a Ample 
.retort, with its neck introduced into a receiver. Fig. 7, 
a tubulated retort. 
Receivers, or balloons are veffels, ufually of glafs, of 
a fpherical form, with a.large flraight open neck, into 
which the neck of the retort is ufually inferted. When 
any proper fubflance, in the different chemical experi¬ 
ments, is put into a retort, and heated, its volatile parts 
pafs over into the receiver, where they are condenfed. 
•But in fome operations, fuch a prodigious quantity of 
.vapours are difengaged, that it is dangerous to condenfe 
■them ; and there is alfo a confiderable lofs in the product: 
to obviate or remedy thefe defefls, Woulf introduced 
his ingenious and elegant apparatus. Fig. 8, reprefents 
a fiHall receiver with the neck of a retort introduced into 
.it. Fig. 9, a large balloon; fig. 10, a phial, often ufed 
as a receiver; fig. n, a proof or difengaging bottle ; fig. 
■12, a tubulated proof, with a moveable bent glafs tube; 
<fig, i3, adopter?, or glafs veffels, open at both ends, and 
I S T R y. 191 
let into each other, for the purpofe of forming tubes, to 
unite certain parts of the different apparatus. 
The alembic, is a veffel ufed for difiillation, when the 
products are too volatile to admit of the ufe of the lafl- 
mentioned apparatus. It confifls of a matrafs or cucur¬ 
bit, to which is adapted a head, of a conical figure, with 
its external circumference or baf'e depreffed lower than 
its neck, fo that the vapours which rife, and are condenf¬ 
ed againH its fides, run down into a circular channel 
formed by its depreffed part, from whence they are con¬ 
veyed by the nole or beak projecting from the head, into 
the receiver; as fhewn at fig. 14. This inflrument is 
lefs Ample than the retort, which certainly may be ufed 
for the molt volatile products, if care be taken to apply 
a gentle heat on fuch occafions. But the alembic has its 
conveniences. In particular, the refidues of diflillations 
may be eafily cleared out of the matrafs ; and in experi¬ 
ments of fublimation, the head is very convenient to re¬ 
ceive the dry products, while the more volatile and elaflic 
parts pafs over into the receiver. 
Fig. 15. is the drawing of an alembic on a larger fcale, 
commonly made in metal : this is placed on the common 
fmall furnace. It is extremely uleful for many experi¬ 
ments in the fmall way. 
Fig. 16, is the delineation of the common Hill ufed in 
the difiillation of ardent fpirits. Inllead of ufing a re¬ 
frigeratory or receiver, the fpirit is made tc pafs through 
a fpiral pipe called the worm, which is immerfed in a tub 
of cold water, and reprefented by the dotted fcroll on 
the tub. During its pafl'age it is condenfed, and comes 
out at the lower extremity of the pipe, in a fluid form, 
and is let off by a cock into a receiver or jug. Fig. 17, 
is a copper veffel for diddling in water-bath; it fits into 
the mouth of the Hill, and the fame head ferves for both. 
The mod eflential article in operations made by fire, 
is the furnace ; and yet the bed conflruflion of a furnace 
does not appear to have been well afcertained from ex¬ 
perience. There are fa< 5 ls which fhew that a fire made on 
.a grate near the bottom of a chimney, of equal width 
throughout, and open both above and below, will pro¬ 
duce a more intenle heat than any other furnace. What 
inay be the limits for the height of the chimney is not 
afcertained from any precife trials ; bu.t thirty times its 
diameter would not probably be too high. It feems to 
be a difad vantage to .contrail tire diameter of a chimney, 
fo as to make it fmaller than that of the fire-place, when 
no other air is to go up the chimney than what has pafled 
through the fire; and there is no profpeil of advantage 
to be derived from wideni ngit. 
Ftg. 18, exhibits the common fmall evaporating fur¬ 
nace. This is not only ufed in evaporations, but likewife 
for digedion, diffolution, difiillation; and all thole ope¬ 
rations which require a heat neceffary only for the ebul¬ 
lition of liquids. Sometimes the veffels are placed di- 
reilly over the coals, which is called working with an 
open fire ; fometimes fand or water is interpofed, when it 
is either called the fand-batb , or balneum maria. This 
furnace is compofed of an afh-hole and a fire-place, part¬ 
ed by a grating which holds the fuel. There are gene¬ 
rally two or three flits made through the walls of the fur¬ 
nace,, towards the top, to favour afpiration and com- 
buflion. 
Fig. 19, fhews the reverberatory furnace. This is ne- 
ceflary for the dilliilation of fubitances, for which a re¬ 
tort mull be idled, and which require a higher degree of 
heat. It is compofed of four parts ; the afh-pan, to give 
pafl’age to the air, and to receive the allies which fall 
down ; the fire-place, heated off by a grating to fuflain 
the fuel; a portion of a cylinder, called a. laboratory, be¬ 
caufe it is this part which receives the retorts employed in 
the labour of dilliilation ; thefe three pieces are covered 
with a dome, or ponion of a fphere, perforated in the 
middle to give paflge to the air, and which forms the 
chimney. The dome ferves to reflect the flames, and 
cauies- 
