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When the operation is once commenced, the water in 
the tube preferves conftantly the fame altitude, which is 
only altered in the five following cafes: i. When the de- 
velopement of the gas, by imprudently increafing the 
heat, or from other caufes, takes place with fuch rapi¬ 
dity, that the gas cannot pafs with fufficient fpeed 
through the communicating tube, and confequently ac¬ 
cumulates in the firft bottle. In this cafe the water rifes, 
and, if the mafs be great, and the tube of fafety not 
long enough, all the water in the firft bottle is forced 
through the tube of fafety, and the apparatus is fponta- 
neoufly opened. The tube of fafety, in this cafe, there¬ 
fore, prevents the apparatus from breaking. 2. When 
the denlity of the water, in the fecond and third bottles, 
is increafed by the gas which it has already imbibed. 
For this reafon we (hould never pour too much water into 
one bottle, but rather diftribute it in feveral; or the 
ends of the communicating tubes fhould not be immerfed 
fo low, becaufe in nwft operations the denfity of the li¬ 
quid is at laft confiderably increafed, and of courfe the 
refinance becomes greater. 3. As foon as the develope- 
rnent of the gas begins to decreale, the water in the tube 
of fafety delcends. This happens either towards the 
end of the operation, or when the heat is imprudently 
diminifhed If the apparatus be then perfectly cooled, 
the air in the firft bottle is condenfed to fuch a degree, 
that the atmofpheric air enters the tube of fafety. If 
this tube were wanting, the water contained in the fe- 
cond bottle would neceffarily come over into the firft. 
It would be the fame with the third bottle, if we were 
not to open the capillary tube of the fecond communi¬ 
cating tube, and thus caufe the atmofpheric air to enter. 
If the communicating tube be without a capillary tube, 
the luting of the third bottle muft be inftantly opened, 
and the bottle itfelf removed. 4. The height of the 
water in the tube of. fafety decreafes alfo at laft, in con- 
f'equence of the lecond and third bottle becoming cooler, 
or when from any other caufe the abforption of the gas 
is more rapid than its developement. 5. Not unfre- 
quently alfo it happens in the midft of the operation, 
that the gas, inltead of being developed, is ablorbed for 
a fhort time by the mafs contained in the retort, or that 
the. volume of this mafs is otherwife fuddenly diminifhed, 
which, in like manner, caufes the water in the tube of 
lafety to fall. The tube of fafety, therefore, not only 
defends the apparatus from breaking, but alio prevents 
the fluids in the bottles from mixing. It ferves more¬ 
over as a mean by which we may judge of the progrefs 
of the operation. « 
_ If, daring the procefs, we fhould obferve a fmall quan¬ 
tity of gas unabforbed pafs through the open neck'of the 
third bottle, a fourth bottle is immediately to be joined 
with the third bottle, by means of a communicating tube, 
in the fame manner as the third bottle is conneiled with 
the fecond. But on this occafion we fhould not forget 
that the preffure is increafed in the firft bottle, and con- 
fult the tube of fafety. When the operation is finilhed, 
and the apparatus cooled, we find the water contained in 
the bottles impregnated with the developed gas, and more 
fo in the firft bottle than in the laft. The liquor con¬ 
tained in the firft bottle is frequently not quite pure, be¬ 
caufe the fmall quantity of the body which comes over 
in the liquid form carries along with it the impurities of 
the diftiiled fubftances ; the other liquors, are, however, 
perfectly pure. If the weight of the water poured into 
each bottle has been accurately determined, we fhall be 
able, after the operation is finilhed, to point out in the 
moft precife manner, from the increale of weight, not 
only the whole weight of the gas obtained, but alfo the 
degree of concentration of the fluids in each bottle. By 
way of example, 1 we will ftate the refult of an operation 
for a preparation of fpirit of cauftic ammoniac. One 
pound and a half of dry fal-ammoniac, and four pounds 
and a half of quicklime, were introduced into.a glafs re¬ 
tort in this--manner; half a pound of lime was put at the 
S T R Y. 
bottom by itfelf, upon this was thrown a mixture of three 
pounds and a halfvof lime, and one pound and a half of 
fal-ammoniac, and the whole laftly covered with the re¬ 
maining half pound of lime. The retort was-placed on 
a fand-bath, and connected with an apparatus of the na¬ 
ture before deferibed. Diftillation was now commenced, 
and continued, by a heat gradually increafed to the igni¬ 
tion of the retort, till the gas ceafed to come over. To 
immerfe the tube of fafety, three ounces of diftiiled water 
were poured into the firlt bottle, and half a pound into 
each of the fecond and third. The apparatus being open¬ 
ed, the firft bottle was found to contain four ounces, two 
drams, forty grains, of a foul weak fpirit of fal-ammoniac ; 
the.fecond bottle, one ounce and a half, twenty-eight 
grains, of the ftrongell and pureft fpirit of fal-ammoniac; 
and, in the third bottle, nine ounces and a half, three 
drams, fixteen grains, of an equally pure but weaker fpirit. 
Bottle. Water. Increafe of Gas. 
No. 1 3 ounces 1 ounce 2 drams 40 grains 
2 8 ounces 4 ounces - 28 grains 
3 8 ounces x ounce 7 drams ifi grains 
19 ounces 7 ounces 2 drams 24 grains 
From this computation it appears, that'one pound and 
a half of fal-ammoniac affords feven ounces, two drams, 
twenty-four grains, of pure gafeous ammoniac, which, 
diflbrved in nineteen ounces of water, form twenty-nine 
ounces, two drams, twenty-four grains, of fpirit of fal- 
ammoniac, of which the fmall portion contained in the 
firft bottle is weak and impure, and cannot therefore be 
computed ; that contained in the fecond bottle is very 
ftrong, fince two parts water contain one part gas; that 
the third portion is alfo pure, but lefs ftrong, the pro¬ 
portion of the gas to the water being about 1 : 5. 
If the products which come over in any diftillation 
whatever, appear partly in a liquid form, and partly in 
that of gas, three different cafes may occur. 1. That the 
gas which comes over is foluble in water, and may thus 
combined with it be received feparately from the body 
which comes over it in the liquid ftate. 2. The gas which 
comes over, whether it be foluble in water or not, may 
be collected in this ftate, and at the fame time the liquid 
body may be feparated without any lofs. 3. If the gas 
which comes over be two-fold, and partly foluble in wa¬ 
ter and partly not, the foluble part combined with water, 
the ipfoluble part in the form of gas, and the body in the 
liquid form, all three may be obtained feparately, and 
without any lofs. 
In the firlt cafe, the apparatus is to be difpofed as re- 
prefented by fig. 1, that is, the beak of the retort is in- 
ferted in the tubulated balloon, which is connefted by 
means of a communicating tube, of which the ends are 
equal, with a Woulfe’s bottle with three necks, in fuch 
a manner that the ends of the communicating tube only 
reach into the neck of the balloon and of the bottle. In 
one of the collateral necks of this bottle we infert the 
tube of fafety; and the third neck is combined with a 
fecond bottle, by means of a communicating tube with 
unequal ends, fo that the Ihorter end only extends into 
the neck of the firft bottle, and the longer end almoft to 
the bottom of the fecond bottle. In fome cafes, this fe¬ 
cond bottle may- be linked in a fimilar manner with a 
third. The balloon is left empty; in the firft bottle in¬ 
troduce the water which is required for the immerfion of 
the tube of fafety, but in the fecond and third bottles pour 
the water which is to abforb the gas. 
The body which in the diftillation comes over in the 
liquid form, colledts immediately in the empty balloon, 
and remains at its bottom ; but the galeous fluids, after- 
having forced the common air out of the apparatus, rife 
through the firft communicating tube into the firft bottle, 
where, having produced the neceffai-y preffure in the tube 
of fafety, they pafs on through the fecond communicating 
tube into the fecond bottle, to combine with the water 
which it contains* After the operation is finilhed, the 
ballooa 
