C H E M I 
and fcrewed into the bell-glafs A. Fig. 5. an elaftic- 
gum bottle, capable of containing thirty ounces of di(- 
tilled water, for holding the acid gafes: whenufed, it is 
fcrewed into the top of the transfer glafs at fig- 3 ' the 
bottom cock of the latter being at the fame time joined to 
the bell-glafs A, previoufly charged with the alkaline 
gas: the cocks being turned, the gafes rufii together in 
vacuo. Fig. 6. a fmall portable air-pump, forexliaulting 
the glafs globe at fig. 4. 
One of the principal obje&ions to the ufe of mercury 
in fuch experiments as this apparatus is intended for, 
has been, the great force neceffafy to overcome the re¬ 
finance of a column of mercury when gafes are to be re¬ 
ceived over that denfe fluid; a refiftance in the propor¬ 
tion of one inch of mercury to fourteen inches of water, 
and which very few lutes are able to withfland. This 
refiftance however maybe overcome by a bent tube fitted 
into the beak of the retort, (if one be employed,) or 
into a Woulfe’s bottle, and palling into the upper part 
of the fmall receiver, expreffed in the plate at C. By 
employing mercury for fuch experiments, another ad¬ 
vantage is gained by the ufe of this apparatus, namely, 
a power of exhauftion in the retort, or Woulfe’s bottle, 
equal to a column of two inches of mercury, or twenty- 
eight inches of water. This will be eafily conceived, 
when it is recollected that, by drawing up the large re¬ 
ceiver A, the linall one C is raifed in its ciftern, hearing 
up with it the contained mercury, which is kept in its 
place by the preflure of the atmofphere on the lurface of 
the mercury in the ciftern. The cock of the fmall re¬ 
ceiver C is then to be turned off, and that of the large 
one A to be turned on. The air, of which the retort, 
or Woulfe’s bottle, is thus exhaufted, may then be let 
out, by plunging A into the mercury between the cy¬ 
linders B B, and turning off the cock. When a fuffi- 
cient quantity of gas pafles from the retort, or bottle, 
through the bent tube into C, to level the mercury in it 
and the ciftern, the communication may again be open¬ 
ed, and the fame Heps followed as before defcribed. By 
this means Mr. Pepys was enabled to obtain more gas, 
from the fame materials, than if he had received it 
through a fluid of the weight of water; a circumftance of 
fome importance where nice and accurate refults are to 
be made. 
GUYTON’S EUDIOMETER. 
Chemifts have long wilhed for an eudiometer capable 
of fhewing exactly the' quantity of oxygen gas mixed in 
any other gas. Berthollet has proved, in his LeCtures at 
the Normal School, that the eudiometer of Scheele, 
which he juftly confidered as the beft, has ftill great de¬ 
feats, as the abforption requires feveral hours, and as 
towards the end there is a decompofition of water, and 
confequently a difengagement of hydrogen gas, which 
occafions uncertainty refpeCting the quantity abforbed. 
This induced Guyton to leek for lome fubftance, which, 
in a convenient manner, might immediately give a more 
accurate refult than nitrous gas, hydrogen gas, phof- 
phorus, and a mixture of fulphur and iron, the only fub- 
ftances hitherto employed for that purpofe. Sulphure 
(fuiphuret) of potafh, appeared to him fit to be tried 
under this point of view. He was well aware that at the 
ordinary temperature, it is fufceptible only of a com- 
bullion ftill flower, and more infenfible, than a moiftened 
mixture of fulphur andiron; but he prefumed that, if 
the temperature were raifed by applying a fmall taper, 
it would befufficient to put in aClion the affinity, and to 
determine rapidly an abforption which would not then 
be afteCted by any foreign caufe. The effeCt fully an- 
fwered expectation ; fo that the queftion then only was, 
to determine the apparatus neceflkry to form this new 
eudiometric inltrument. He thought that an inverfed 
retort would unite fimplicity, convenience, and every 
advantage that could be defired. This inltrument, thus 
Von. IV. No. 104. 
S T R Y. 3 8r 
completed, is exhibited in the Chemiftry Plate VIII. at 
fig. 7. AB is a glafs retort with a long neck, and ca¬ 
pable of containing from twelve to fifteen centilitres, 
which is about eight cubic inches. One mult be chofen ' 
fo much bent that, when the neck is placed vertically, 
the bulb may form in its lower part a cavity containing 
the matters introduced into it. The extremity of the 
neck is ground with emery, to fit air-tight at C into the 
glafs tube C D, open at both ends, and twenty or twen¬ 
ty-five centimetres in length, (a centimetre is about four 
lines or tenths of an inch,) F is a cylindric velfel, or 
common glafs jar, into which the tube of the glafs C D 
may be entirely immerfed below the furface of the water. 
When you wiffi to try any aeriform fluid, in order to 
feparate its parts, and difeover the quantity of refpirable 
air it contains, put into the retort two or three bits of 
fulphure of potafh of the fize of a pea; fill it with water, 
taking care to incline it to make all the air which might 
remain in the bulb pafs into the neck; (lop with the 
finger the orifice of the retort, and place it in the pneu¬ 
matic ciftern, that the gas to be tried may be introduced 
in the ufual manner. By inclining it again, alternately 
in different directions, all the water may be eafily dil- 
placed, and the fulphure left remaining in the bulb. 
Then place the retort vertically, and introduce the end 
of it into the glafs tube CD, which mult ftill be under 
water; and place below the bulb a fmall lighted taper. 
To preferve the retort in its pofition, a cover of wood, 
with an aperture for its neck to pafs through, fhould be 
fitted to the jar. 
The firlt impreffion of the heat dilates the gafeous fluid, 
fo that it defeends almoft to the bottom of the tube, 
which has been difpofed on purpofe to receive it, and to 
hinder any part of it from eicaping, which would be the 
cafe if the tube were not fufficiently long, and which 
would prevent the diminution from being accurately 
determined. As foon, however, as the fulphure begins 
to boil, the water afeends with rapidity, not only in the 
lower tube, but alfo in the neck of the retort, notwith- 
flanding the application or even augmentation of the 
heat. If it be vital air, abfolutely pure, the abforption 
is total. In that cafe, to prevent the veffel from burlting, 
wnich might happen were it cooled too fuddenly, the af~ 
cent of the water mult be retarded, either by removing 
the taper, or inclining the retort, which will not hinder 
the abforption to continue, while there remains gas pro¬ 
per for maintaining combuftion. 
If it be common air or vital air mixed with any other 
gas, you muft, after cooling, meafure the quantity of 
water which has entered the retort, and which will ex¬ 
actly reprefent the bulk abforbed. You mult not negleCt 
to confine the remaining gas under the fame preflure, by 
immerfing the retort in the pneumatic ciftern, till the 
internal and external water be on the fame level, before 
you clofe the orifice by a Hopper. This operation, very 
eafy when you have graduated veflels, may be made in 
common practice by means of a piece of paper cemented 
along the neck or the retort, and having traced out 
on it divifions determined by experiment, and which 
may be covered with varnifli, to defend it from the action 
of the water. 
C. Chauflier has conftrudted, for eudiometric experi¬ 
ments by phofphorus, an apparatus fomewliat different, 
compofed of a long tube all of one piece, one end of which 
is bent and blown into a bulb, and having, as ate, atu- 
bulure fhut with a Hopper after the water has been marie 
to alcend in the infide of the tube to two-thirds of its 
height. This inltrument would ferve alfo for experi¬ 
ments with the fulphure of potaffi ; but we muft obferve, 
that the execution of it isnot fo eafy as on the firlt view 
might appear. Befides, if the tubulure renders it very 
convenient for trying atmofpheric air, the cafe is not the 
fame in regard to other gafes which cannot be introduced 
but by tranfmiffion. 
New 
