―47―

Art. III.

Transactions of the American Philo-
sophical Society, held at Philadel-
phia, for promoting useful Know-
ledge.

[Continued from p.445 of vol. i.]

THE following papers have re-
lation to a subject of great
importance in the present state of
our country. The first is

A Mode of drying up the Marshes in
the maritime parts of North-Ame-
rica. By Thomas Wright, of the
College of Surgeons, and Teacher
of Anatomy in Ireland.

The free operation of wind and
sun, is well known to promote
evaporation. Pools and marshes,
the usual source of febrile and epi-
demical diseases, are augmented by
being encompassed and oversha-
dowed by forests. Vegetation tends
to augment them, not only by col-
lecting and condensing the moisture
dispersed through the atmosphere,
but by preventing its subsequent
escape by evaporation. The obvi-
ous mode of drying the soil by dig-

gings pits and canals, into which
the water will flow from the higher
surfaces, will seldom be attempted
from any motive but interest, whose
influence is limited and partial; is,
in all cases, expensive and labori-
ous, and in many cases utterly im-
practicable. The position of the
ground, in relation to adjacent
parts, may not admit of a canal or
an outlet. This mode can never
do more than remove the water.
The causes of its collection and
accumulation being as numerous
and powerful as ever, the evil is al-
leviated but not removed. The
effectual remedy consists in re-
moving the foliage and the shade,
by which the winds are impeded
and the solar rays are shut out, and
thus preventing the moisture from
condensing, by the same means by
which we cause it, when it is con-
densed, to evaporate and disappear.

The progress of culture and po-
pulation will, no doubt, produce
this effect in America. When the
ground is wanted for raising flax
and corn, and for pasturing oxen
and sheep; when the timber is re-
quired to construct houses and ships,
to furnish heat to furnaces and
ovens, our forests will gradually
disappear, the pool and bog will
become dry land, rain will be less
frequent and copious, torrents will
be less impetuous, and rivers will
shrink into narrower channels.
The sources of diseases will be
somewhat lessened, and not only
greater numbers will partake of the
blessings of existence, but will en-
joy it for a longer time, and with
fewer intervals of debility and pain.

It is to be feared, however, that
this effect will never be otherwise
produced; and that all projects for
anticipating the effects of culture,
are airy and chimerical. The ob-
stacles will arise from the indolence,
ignorance, and wants of mankind;
and not, as Mr. Wright imagines,
from the usefulness of wood as fuel.

―48―

He fears that we should be obliged
to spare our woods, because our
soil has not yielded so many veget-
able crops, as to form, by their de-
cay, peat or combustible turf, in-
ferring, in the true spirit of his
countrymen, that the only substi-
tute, in culinary processes, for tim-
ber, is peat. His apprehensions
are kind, but groundless. When
there is nothing to be found above
the surface, we shall always procure
enough to warm our fingers and to
make the pot boil below it. When
we cannot hew logs and cut turf,
we must dig for coal, and of that
there will never be a scarcity. To
obviate this objection, however,
and to keep most of our hiccories
and pines sacred from the axe, he
proposes that immense vistas, fifty
or an hundred miles in length,
should be made in our largest forests,
in the direction of our N. W. and
S. E. winds, whose blasts will thus
be suffered to pervade, exsiccate,
and make suitable for settlers, by
diminishing the insalubrity of, large
portions of the country.

Experiments and Observations on
Land and Sea Air. By Adam
Seybert, M. D.

The inquiry as to the ingredients
of air, zealously and so successful-
ly pursued in the present times, was
naturally connected with subse-
quent inquiries as to the propor-
tions between these ingredients in
different circumstances. Dr. Sey-
bert has undertaken to improve our
knowledge on this curious and im-
portant subject, by recounting, in
this memoir, a series of experi-
ments made to estimate the com-
parative purity of the air, upon land
and water. After renumerating the
opinions and observations of several
eminent philosophers, Ingenhousz,
Priestley, and Fontana, upon the
purity of air in different situations,
he proceeds to state the results of
his own attempts. These lead him
to conclude, agreeably to Fontana's

decision, and contrary to the popu-
lar belief, that, on land, the air in
different situations, is of nearly the
same degree of purity.

His experiments were made on
air collected in the streets and
court-yards of Philadelphia, on the
verge of a marsh washed by the tide,
in the neighbouring roads, and on
the summit of an eminence near
Schuylkill. In all these cases the
air was proved to possess the same
degree of purity.

Of experiments made with the
same view, at sea, and in the bay
of Chesapeake, he speaks as fol-
lows:

“My experiments at sea, suf-
ficiently prove that the atmosphere
is considerably purer there than on
land. Though there are some
trifling differences in the results of
several experiments, I have no rea-
son to believe that they were owing
to the difference of latitudes or lon-
gitude in which they were perform-
ed. I can form no system respect-
ing such variations. Winds, tem-
perature, rain, &c. do not seem to
have produced them. As they did
not observe any regularity in their
occurrence, they may, perhaps, be
attributed to certain unperceived
errors, which are unavoidably at-
tendant on such trials.

“That the air at sea should ap-
pear nearly of the same purity in
different latitudes, does by no means
astonish me; for, if land air has
certain matters mixed with it, they
are, perhaps, absorbed: and if my
supposition be true, that the influ-
ence of the sun's rays on the water
tends to increase its purity, the
opinion I entertain is not surprising.
For when once purified, there are
perhaps none, or few causes to
render the air noxious, after it is
wafted from our towns and cities
over a large body of water.

“It occurred to me that, proba-
bly, the purity of the air at sea
varied at different periods of the day:

―49―

to satisfy myself on this point, I
made several trials on the 10th and
17th of June last. On the 10th, I
performed them at nine o'clock A.
M. at twelve, and at six o'clock P. M.
On the 17th, at nine A. M. and at
twelve o'clock. The result of all
the experiments of the same day,
was exactly similar; at least, not
perceptibly different.

“Whether sea air might not be
rendered more pure by agitation
with water, appeared to me a ques-
tion worthy of being ascertained:
particularly, as some celebrated men
maintain that it has this effect, and
must hence be looked upon as one
of the greatest resources which we
have for purifying the atmosphere.
Sir John Pringle and Dr. Ingen-
housz are of this opinion. But
some of Dr. Priestley's experiments
seem to contradict it; and so does
the following assertion of the cele-
brated Scheele, who says, ‘L'air
ne s'unit pas avec l'eau commune.’
Traité de l'air and du seu, p. 51.

“My experiments on this head
are as follow: on the 26th and 28th
of June, the 2d and 5th of July,
equal bulks of sea water and air
were agitated for half an hour in
my eudiometer tube; but I never
discovered any absorption to have
taken place; neither was the air
rendered purer, as was evident from
a mixture with nitrous air.

“It now appeared probable to
me, that sea water was already sa-
turated with all the gaseous particles
it could absorb; and that fresh water,
when agitated with sea air, might
diminish its bulk or alter its purity.
In consequence of this supposition,
equal bulks of sea air and fresh
water were agitated as above, but
it was not in the least altered. Not
entirely convinced of the fallacy of
my conjecture, I boiled sea water a
sufficient time to purge it of the air
it might contain. I then agitated
sea air with this boiled water as
above, and found no difference

from the other experiments. These
results tend to confirm my belief,
that if sea water purifies the air, it
is rather by adding somewhat to it,
than by absorbing any considerable
quantity of effluvia floating therein.
Though by this I do not mean to
say, that certain matters, foreign to
our atmosphere, do not float there-
in on land. If they exist, perhaps
they may be subject to absorption
by water.”

This memoir concludes with a
table very accurately and satisfac-
torily constructed and arranged,
and exhibiting the results of twenty-
five experiments, made in different
temperatures of the air, different
positions of the wind, different
times of day, at sea, between the
latitudes of 37° and 42°, and in
the bay of Delaware, between 5th
June and 18th July. These ex-
periments produced nearly the same
result. We shall not pretend to de-
cide how far Dr. Seybert's conclu-
sions are weakened by the imper-
fections of his instrument. Fon-
tana's eudiometer is essentially de-
fective.

Experiments and Observations on the
Atmosphere of Marshes. By the same.

We cannot detail the numerous
experiments by which the author of
this paper has endeavoured to prove
that the air generated by marshes,
differs from that of other places;
that this difference consists in its
possessing a disproportionable quan-
tity of carbonic acid gas, and no
oxygen whatever; that the air above
marshes, that is, their actual atmos-
phere, as well as that upon their
verge, are not impurer than ordi-
nary.

As to the cause of this difference,
he speaks in the following manner:

“The putrefaction of the animal
and vegetable matters upon the soil
of marshes, is the great cause of the
changes observed to exist: for every
species of soil will not operate in
the manner alluded to.

―50―

“That the cause is in the putre-
faction of these matters, and that
this state is absolutely necessary to
those changes, I infer from the fol-
lowing circumstance: marshes have
no noxious influence during the
winter season. They cause disease
when the circumstances are present
which promote putrefaction; as, a
proper degree of heat, a due quan-
tity of moisture, and the contact of
atmospheric air, or substances capa-
ble of affording oxygen, as water.
That certain degree of moisture is
necessary, appears evident from
White's experiments, related in the
Philosophical Transactions: he says,
‘a certain degree of moisture seems
necessary to produce the bad effects
of marshes; for mud, when per-
fectly dry, did not altar the air.’ He
might have added, that too much
fluidity will likewise prevent their
bad consequences, which is proved
by the neighbourhood being healthy
when they are overflowed. An
overflow of water may operate by
preventing the powerful effects of
the sun. Experience teaches us
that their bad effects are discon-
tinued when they become dry.
Covering them with clay and other
substances not liable to putrefac-
tion, destroys their bad effects; so
does cultivation, frost, &c.

“Living trees being planted in
their neighbourhood, renders the
situation more healthy, by absorb-
ing the gas exhaled during putre-
faction, and affording oxygen gas.

“White's experiments prove,
‘1st. During sixteen hours, air con-
fined in a phial over water, did not
suffer a change. 2dly. Pure clay
moistened, did not alter the purity
of the air. 3dly. Sand moistened,
did not change the purity of the air.’
But 4th. Mud (which consists of
earths intimately mixed with dead
animal and vegetable substances)
rendered the air very impure, as I
proved by the experiments which I
performed.”

The purity of the actual atmos-
phere of marshes, that is, its pos-
session of the usual proportion of
oxygen, is explained by setting the
influence of living vegetation in
opposition to that of the dead. The
carbonic produced by the pu-
trescent mass which constitutes the
soil, is supposed to be absorbed by
the living vegetable growth above;
while, from the latter, oxygen is
continually disengaged. On this
subject, we will quote his own
words.

“A variety of facts prove that
oxygen gas is a principal ingredi-
ent in the atmosphere of marshes:
1st. Candles burn therein with the
same lustre as in other situations.
2d. Animals breathe with equal ease
as in other places. 3d. Eudiome-
trical experiments prove that it forms
as great a proportion here, as in
other atmospheres which are reck-
oned more healthy.

“August 4th and 5th, 1796—
July 8th and 10th, 1798, I collect-
ed air from over marshy grounds,
to the south and north of Philadel-
phia; when tried with the eudio-
meter, they always proved as pure
as the air in the yard of my lodg-
ings. Chaptal, in his Memoirs de
Chimie, p. 141, asserts that the air
over the ponds which border on the
Mediterranean sea (the neighbour-
hood of which is equally marshy,
if not more so, than the neck form-
ed by the junction of Schuylkill
and the Delaware, as I convinced
myself during my residence at
Montpellier in the years 1795 and
1796), was equally pure with that
of Montpelier, tried the same day.
When I assert that the atmosphere
of marshes is equally pure with that
of other situations, I mean that it
contains as large a proportion of
oxygen gas as such other atmos-
pheres do. I do not, by any means,
intend to be understood that it is
free from foreign mixtures.

“I have acknowledged that pu-

―51―

trefaction is going on in marshy
places, and likewise admit that this
process destroys the purity of the
atmosphere by absorbing its oxygen;
therefore, it may seem difficult to
admit the absolute purity of the air
being equal here to that of other
places. People being able to breathe
with ease over marshy grounds, is
sufficient proof that the oxygen gas
there is adquate to support life.
I shall now attempt to account for
the purity of the air of marshes, as
follows: Sennebier has proved, by
numerous experiments, that living
vegetables, placed in an atmosphere
of carbonic acid gas, or in water
saturated with this air, exposed to
the action of the sun, thrive and
grow very rapidly: during the ex-
periments the carbonic acid is de-
stroyed, and oxygen gas is disen-
gaged. In addition to these experi-
ments, Ingenhousz has taught us
that the aquatic plants, particularly
such as grow in the neighbourhood
of marshes, possess the power above
stated to a surprising degree; see
Experiences surles Vegètâux, Tom.
2. p. 401. These facts, when pro-
perly considered, and connected
with the remarks I made when
speaking of the effects of mud on
the atmosphere, I think are suffi-
cient to account for the phenome-
non which, at first, seemed at least
doubtful.

“The above view of this difficult
subject, will, perhaps, in some
measure alter our opinions respect-
ing the utility of marshes. Here-
tofore, mankind seem to have view-
ed their existence as noxious to
them, and unnecessary to their hap-
piness. I confess my former opi-
nion respecting them, coincided
perfectly with that of the majority,
but at present my ideas are very
different: I consider them as very
necessary to keep the atmosphere
in a proper degree of purity, for it is
not only the impure atmosphere
which kills animals, but the too

pure also; and an ingenious philo-
sopher has well observed, that ani-
mals live too fast in atmospheres
overcharged with oxygen gas. They
appear to me to have been instituted
by the Author of Nature, in order
to operate against the powers which
vegetables and other causes possess
of purifying the atmosphere, so that
the oxygen may exist in a proper
proportion, fit to support animal
life and combustion. I am of
opinion that, ere long, marshes will
be looked upon by mankind as gifts
from Heaven to prolong the life and
happiness of the greatest portion of
the animal kingdom. Perhaps it
was originally intended that they
should remain uninhabited, and that
their only use should be that of
correcting the too pure atmospheres.
Although their immediate inhabit-
ants suffer disease from them, still,
but a small portion of the human
race choose marshy situations for
their residence.”

The concluding remarks on the
benefits of marshes, are liable to
some exception. If the atmos-
phere of marshes be equally salu-
brious with that of other places, it
is so because the fluid exhaled from
dead plants is the proper food of the
living; which, while they consume
the air noxious to animals, are busy
in producing that which is useful
to them; but it is likely that part
only of this noxious vapour is de-
voured on the spot, and that the
rest is dispersed over the adjacent
regions; and that so far from pro-
ducing merely an equilibrium, the
hurtful gases predominate exactly in
proportion to the extent or the
proximity of marshes.

This is the lesson of experience.
To be covered with thick umbrage,
and entangled in slimy bogs, is to
be sick. To be high and dry, to
bask in the rays of the sun, and to
be fanned by unobstructed breezes,
are the means of health. While
experience evinces that health is en-


―52―

joyed in proportion as bogs disap-
pear, we shall not readily applaud
them as the gifts of Heaven.

The inevitable tendency of culti-
vation, is to annihilate marsh. The
effect of incultivation, is to turn the
whole level and cultivable parts of
the globe into vast dismals. Few
will acknowledge, with Dr. S. that
they were originally intended to re-
main uninhabited, for that is to say
that the earth was not designed to
be the dwelling place of men; but
most persons will maintain that
their only use is that of producing
corn and pasturing cattle, for which
purpose they must loose their na-
ture and become dry land.

We know that their beneficial
effects, whatever they be, are out-
weighed by their hurtful ones. We
may, indeed, according to the
addage, have too much even of a
good thing; and therefore, though
the good thing called marsh is injuri-
ous when we have too much of it,
yet, when moderately distributed,
it may be beneficial. This con-
cession, however, is of not much
value. At present, it is plain that
we have too much of it, and that
we have no reason to check or curb
our industry in annihilating bogs
from the dread of doing too much.
While we have running waters,
respirable organs, and combustion
(necessary not merely for warmth
sake, but for culture, cookery, and
the various arts), while we have the
putrefaction of plants and animals
useful to subsistence, we need not
fear that our atmosphere will be-
come too pure.

On the Insalubrity of Flat and
Marshy Situations, and the Means
of correcting it. By William
Currie.

This treatise has little resem-
blance to the foregoing. It is not
the detail of experiments, but a se-
ries of speculative remaks on the
experiments of others. We shall
not recapitulate Mr. Currie's argu-

ments and facts to shew that the un-
wholesomeness of marshes arises
not from vapours or miasmata ac-
tually emitted from the soil, but in-
directly from the abstraction of the
oxygen of the atmosphere. Whe-
ther disease be produced by the air
of marshes, in consequence of that
air having too much of one thing,
or too little of another, by being
deficient in oxygen or superabun-
dant in certain pestiferous effluvia,
is a question that we shall leave in
the hands where we find it, and
shall content ourselves with quoting
Mr. Currie's concluding observa-
tions.

Having, as he thinks, established
the position that the putrefaction of
bogs and fens is hurtful, by di-
minishing the due proportion of
oxygen in the ambient air, he pro-
ceeds to point out the prophylaxis
thus:

“The remedies are to introduce
and increase the proportion of oxy-
genous gas in the superincumbent
atmosphere, and to prevent its fu-
ture abstraction, by cutting off or
diminishing the sources of putre-
faction.

“It would be a happy circum-
stance if the application of the
means suited to produce an amend-
ment in a body so large and fluctu-
ating as the atmosphere, was as
practicable as the means suited to
effect that purpose are obvious:
but, unfortunately, this requires too
much labour and expense to admit
of extensive application, especially
in a country where population and
wealth do not bear a due propor-
tion to the extent of territory.

“We ought, however, to at-
tempt every thing in our power to
effect so desirable and useful an
event.

“Chemistry furnishes various ar-
ticles, by means of which we can
generate and introduce a supply of
oxygen into the atmosphere, as well
as alter the quality of those noxious

―53―

gases with which it is occasionally
contaminated.

“But the grand engine by which
the sources that deprive the atmos-
phere of its salutary and vivifying
principle, are cut off; and the great
magazine from whence a sufficient
supply is obtained, must be sought
for in the art of agriculture.

“The stagnant waters may be
carried off, and the soil of marshes
rendered dry, by means of drains,
deep trenches, and wells; and fur-
ther stagnation and putrefaction
prevented by consuming the dead
weeds, grass, and trees, and by
covering the flats, and filling the
hollows with clay, sand, or lime.

“And the atmosphere may be
supplied with oxygen by cultivating,
on such soils, grasses and plants of
vigorous growth, and especially
those which live and flourish latest
in the season. For vegetables, while
living and growing, when exposed
to the rays of light, constantly de-
compose the water they imbibe
from the earth and air, and while
they retain the hydrogen or base of
inflammable air for the formation
of oil, wax, honey, or resin, they
replenish the atmosphere with oxy-
gen.*

“When it is impracticable to
render marshy situations dry, on
account of their extent, they should
be kept constantly flooded by means
of dams and sluices, to lessen the
effects of putrefaction; for, when
dead vegetable or animal substances
are immersed in water, so as to be
entirely excluded from contact with
the air, putrefaction can only take
place in a slow and imperfect man-
ner.

“But removing the trees and
shrubs from marshy or fenny tracts,
without draining off the stagnant
water at the same time, and destroy-
ing the dead herbage by fire, instead
of rendering such situations more

healthful, has been found to have a
different effect, because a greater
extent of putrescent surface is there-
by exposed to the rays of the sun,
and, of course, a greater portion of
oxygen abstracted from the atmos-
phere. It is owing, in a great
measure, to this circumstance, that
all new countries are so generally
fatal to the first settlers.

“The same land, after it has
been cultivated a few years, espe-
cially if there be sufficient declivity
to prevent the water from stagnat-
ing, looses its unwholesomeness;
the putrescent substances mixed
with the soil or superficial stratum
of the ground having finished the
putrefactive process by that time.
In order, therefore, to render and
preserve marshy countries health-
ful, they should be preserved dry
and clean by means of the spade,
the plow, and the rake.

“When the level situation of a
place prevents the stagnant water
from being carried off by drains,
deep wells should be dug in differ-
ent places for the water to collect in;
by which means a greater portion
of the soil will be rendered dry, and
less noxious.

“To prevent still farther the in-
jurious effects of residing near
marshes or mill-ponds, rows of such
trees as grow rapidly, and retain
their verdure late in the season,
should be planted between those
situations and the mansion, for the
purpose of intercepting the moisture
in its progress, while they furnish
a constant supply of oxygen to the
atmosphere.

“Lodging in the upper story of
a house, has been found to preserve
health during a sickly season, in-
stances of which are recorded by
Sir John Pringle. This appears
to be owing to those situations be-
ing out of the reach of the moisture
from the ground.”

  * Chaptal's Chemistry. Ingenhousz's Observations, &c.