AIR VITIATED BY ADMIXTURE WITH EFFLUVIA ARISING FROM THE DECOMPOSITION
OF VEGETABLE MATTER ON THE SURFACE OF THE EARTH.
It is not only from such sources as those already treated of, that
effluvia or gases arise, to contaminate the atmosphere, and to spread
disease among men and beasts. Effluvia likewise spring from the
putrefaction of vegetables; and, in many instances, from circumstances
favourable to their development and action, they so vitiate the
atmosphere, that its respiration induces some of the most virulent
diseases, and, where the effects are not so serious, a state of slow
sickness and great suffering is often the lot of the sufferer, during
the whole course of his miserable existence. The situations of these
effluvia will shortly be pointed out, along with the respective diseases
incident to them.
But let us for a moment consider the changes on which these effluvia
depend. Putrefaction of vegetable matter is one of the many wise
provisions which the Almighty has instituted for the accomplishment of
his comprehensive plan of the creation.
The surface of the earth is covered with vegetation, to supply man with
food, and likewise to support the various animals placed below him in
the scale of creation, so necessary to his comfort and existence. They
are consumed, and, by means of digestion, become component parts of
animals; and when these, in their turn, die, they go down to the earth,
whence they originally sprung.
Mixed there, with other matters composing the soil, the carcasses of
animals afford nourishment to vegetation again, and once more they are
found as the component principles of vegetable forms. Thus the animal is
constantly supplying food to the vegetable world, which, in its turn,
supplies food to the other again.
In life, we found them performing functions useful to each other, and
mutually correcting their unwholesome effects; in death, they are no
less useful: the one is converted into the other.
All animated creation is the scene of endless changes, and is the object
of successive transformations. ’Tis one mighty circle, of a thousand
parts, constantly revolving,—one part occupying now this, now that
place,—and each taking the place of that next it, till at length it
completes the entire circle; and even then the race is not yet run, the
revolution must be performed again and again, to the very end of time.
The immediate agency by which these wonderful changes are effected, is
putrefaction. We have alluded to it shortly, in connection with man in
health, in disease, and in death.
We have now to speak of putrefaction in connection with dead vegetable
matter, in marshy situations, &c., where it is the occasion of much
disease.
There is no reason to believe that it was the design of the Almighty,
that the process of putrefaction, which is so essential to the great
plan of successive races of animals and vegetables, should be the active
engine of pestilence, which it is in many situations.
That is not the necessary consequence of putrefaction; and when it does
occur, it is rather the effect of accidental circumstances. Under
ordinary circumstances, where putrefaction goes on, as among vegetables
moderately moist, exposed to currents of air, and mixed up with the
soil, as in the various processes of agriculture, no bad results are
experienced.
But when vegetation is allowed to go on year after year, without being
cropped, where, as it ripens, it withers and dies; and when it dies, is
allowed to accumulate and putrefy, where there is much moisture, much
solar heat, and little motion of the air, where, perhaps, other
circumstances are operating, favourable to rapid decomposition, effluvia
are wont to ascend and vitiate the atmosphere.
Such a vitiated atmosphere has acquired various appellations, according
to the place in which it has been observed, and according to the effects
or diseases it produces.
But, under whatever name it passes, its origin is the same, namely,
decomposing vegetable matter on the surface of the earth, perhaps, in
some situations, mixed more or less with dead animal matter.
It is decomposing vegetable matter which produces the yellow fever of
the West Indies, the jungle fever of India, the deadly pestilential
fever of the coast of Africa, the ague in this country and in many
others, the cretinism of Switzerland, the pellagra of Milan, the
unwholesome condition of humanity in many parts of Italy, and especially
in the country surrounding Rome, or the Campagna of Rome, as it is
called. The decomposition, however, takes place under circumstances
somewhat different, and hence the difference in the results of its
action.
These effects are attributed to the decomposition of vegetable matter;
but there is room to think that, along with that, there is combined no
very insignificant proportion of matter of an animal nature.
It may safely be inferred, that wherever there is vegetation, there
animals are found also; and it is well known that vast numbers of many
kinds of animals live wherever decomposition is taking place, especially
if the situation is warm and sheltered. The carcasses of these animals
will be added to the vegetable matter, and add to the common mass of
corruption.
That matter in swamps, and in unwholesome situations, said to be purely
vegetable, is then a compound of animal and vegetable origin; and these
effluvia arise, not from vegetable decomposition only, but from both
dead animal and vegetable substances in a state of putrefaction.
There is little known of the composition of these effluvia. We are most
conversant with their situations, and their effects upon health. In
different situations, they produce different diseases. But no known
facts entitle us positively to say that their composition is different.
It is a remarkable fact, but one well ascertained, that the atmosphere,
in all parts of the world, in all climates, and in all situations, is
much the same in its chemical composition. It manifests the same general
physical characters in all situations, whether healthy or pestilential,
and the nicest investigations have detected nothing in an atmosphere
known to be pestilential, that is not found in the most wholesome.
However, there is much reason to think, that this circumstance is owing,
not to the absence of hurtful gases, but to the comparative
insignificance of their volume beside that of the atmosphere itself, so
vast in its dimensions.
Medical men have been disposed to think that effluvia which cause one
disease, say the yellow fever, are not the same as that which cause
another, say the fever of the coast of Africa. The only reason offered
is the difference of the diseases; but that is not enough to prove that
the effluvia are different in their nature. Different effects, or
effects so modified as to appear very different, are the results of the
same cause on many occasions. The smoke of tobacco will make one person
feel comfortable, another merry, another sick, another faint, and so on;
but it would be unfair, from these differences in the effects, to
pronounce that tobacco-smoke was in all these cases different in its own
nature.
We are satisfied that the effluvia or gases arising from marshy or
unwholesome soil, are the same, generally speaking, in all situations,
whatever disease is produced; and that the difference in the results is
to be attributed to the varying circumstances under which they act,—for
instance, the constancy or inconstancy of their operation, their greater
or less intensity, the greater or less degree of concomitant moisture
and heat, the greater or less amount of motion of the air,—the sheltered
situation of human habitations,—the condition of the body, its
predispositions from native country and the like, and the individual
being accustomed or unaccustomed to the action of effluvia.
Gases are known to arise from the marshy grounds mentioned, where animal
and vegetable matter is putrefying, from the fact, that the
neighbourhood of swamps is most unwholesome, the inhabitants and
visitors almost uniformly suffering, because unwholesome effluvia are
invariably known to emanate where animal and vegetable matter is thus
corrupting, and because the gases themselves may be seen rising in
bubbles out of putrid water, containing dead animal and vegetable matter
in a state of corruption.
These bubbles contain gases the very same as are disengaged when animal
and vegetable matter are putrefying among water. They are nearly the
same as proceed from merely animal matter dead and putrefying, not
incorporated with the soil, viz. carburetted hydrogen, or inflammable
gas, carbonic acid gas, or fixed air, and sometimes a little
phosphuretted and likewise sulphuretted hydrogen.
These gases are sometimes appreciable to the organ of smell. Carburetted
hydrogen is very strong, and is perceptible in many situations where
there is much corruption going on; for instance, at the meadow-ground
between the Dairy, on the Portobello road, and Comely Green, near
Edinburgh, where the stench is so strong as to prove most offensive to
passengers on the road. The source is the corrupting animal and
vegetable materials, in the foul water conducted from Edinburgh, and
made to overflow the ground, for the purposes of irrigation.
In such situations, it is not uncommon to observe lights floating along
during the night, and superstition has not failed to make them represent
evil spirits. They are known by the name of “Will o’ Wisp” and “Jack o’
Lantern;” and have, on many occasions, proved objects of no slight dread
to many ignorant persons. The lights are merely ignited carburetted
hydrogen gas,—the same kind of gas as that used for lighting our shops
and houses.
The gas is ignited, perhaps, by the rising to the surface of the putrid
water, of a bubble of phosphuretted hydrogen, which, as was before
observed, burns the moment it comes in contact with the atmosphere.
Other products of an aeriform kind may be evolved also, but we have no
direct evidence of their existence,—but an atmosphere, loaded with
vapours of the kind mentioned, is enough to account for the production
of the observed disease, in all its varied forms, when there is
conjoined with it other unwholesome agencies. In some countries, the
pestilential air is present throughout the year, for instance, in the
country around Rome, in the fens of Lincolnshire, where ague is seldom
absent; in others it is periodical, chiefly confined to the hot and
rainy seasons, as in India and in the West Indies, where fevers prevail
to a great extent; and in others, again, it is observed only when the
wind blows from a particular direction.
These effluvia are conveyed to a distance by currents, and produce their
peculiar effects, more or less, upon almost all they encounter. The
malaria at Rome is carried by the wind into the city, by the channels
most open to its entrance; and those parts, it is said by medical men
who reside there, that are most exposed to the wind blowing off the
adjacent marshy grounds, are most unhealthy. It is for that reason that
the suburbs are more unwholesome than the interior of that city, where
the wind does not find ready access, on account of the obstacles offered
to its course by the high buildings. The high houses and streets thus
act as a barrier against the entrance of the pestilence, and it is even
said that the narrowest streets there, are the most healthy, as they
shut out the pestilential vapour.
An obstacle of the same kind is offered by hills which interrupt the
course of winds carrying with them vapours from marshy grounds. In the
West Indies, where the yellow fever commits such frightful ravages, many
instances are known where a town or district retains its health, from
the shelter which a hill affords against the visitation of a wind that
has loaded itself with deadly miasms, while sweeping over a marsh or
swamp. It is the practice of those residing in those countries, not only
to remove from the swamps, but also from those points to which the wind
blows after passing over them.
Inattention to that consideration has led to the loss of much human
life, and to the fruitless expenditure of much money in the erection of
houses, barracks, and the like, which, after completion, have been found
to be totally uninhabitable, from the pestilential vapours carried to
them by the winds. In illustration of the influence of winds, we submit
the following interesting extract from Dr Good’s Study of Medicine. He
has been speaking of effluvia from animal matter. “But the foul and
stinking Harmattan,” (a pestilential wind) “when it rushes from the
south-east upon the Guinea coast, loaded with vegetable exhalations
alone, with which it impregnates itself while sweeping over the immense
uninhabitable swamps and oozy mangrove thickets of the sultry regions of
Benin, triumphs in a still more rapid and wasteful destruction; so much
that Dr Lind informs us, that the mortality produced by this
pestilential vapour in the year 1754 or 1755 was so general, that in
several negro towns, the living were not sufficient to bury the dead;
and that the gates of Cape Coast Castle were shut up for want of
sentinels to perform duty. Blacks and whites falling promiscuously
before this fatal scourge.”
So loaded is the air on some occasions with these pestilential vapours,
that they attach themselves to whatever objects they meet, houses, the
sides of hills, and woods, through which they pass along with the wind,
and so completely has a wood stripped the currents of their baneful
accompaniments, that they have been respired after with no injury
whatever.
Trees are found to give great shelter and salubrity to towns in this
way, acting as they do as so many sieves retaining impurities.
It is understood that the effluvia arising from putrefying vegetable
matters ascend high in the atmosphere under the influence of the solar
rays, and spread far and wide, and that at night during the cold they
fall with the dew to the ground again, and impart to it and to those
exposed to its action, much virulence. The ground is there known to be
extremely unwholesome, and those who have been compelled by want, by
sickness, while travelling, overtaking them, or by being benighted, to
lie down with nothing but the soil for a couch, and with no shelter from
the vapours and dew that falls at night, save the sky itself, have felt
this pestilential influence: on the morrow they awake distressed,
parched, and affected with headach, and the usual symptoms of malignant
fever.
With the close of day or the setting of the sun, the pestilential vapour
falls and envelopes the country and the habitations of men with a deadly
mantle—and it is then unsafe to venture into the open air in many of the
finest countries of the world.
The pestilential effects of exposure to these night dews and vapours
have, on many occasions, been experienced by soldiers encamping in the
open grounds, and our gallant countrymen on foreign service are wont to
yield in fearful numbers to a foe, merciless and unsparing.
But it is not in swampy grounds only that these vapours arise, for there
is reason to think that in those places where sickness is constant, and
where no such dampness of ground is observed, that decomposition of
animal and vegetable matter is going on some depth below the surface,
and that the extricated gases issue through the soil. This is rendered
almost certain, by the fact which has sometimes been observed, that the
most dangerous and sickly season is, when the ground is parched and rent
with heat, permitting the exhalations generated below to ascend into the
atmosphere. Instances of this occurred among our soldiers in the
Peninsular war—the season, marked with the greatest prevalence of
disease, the common result of vitiated air, being that when the soil was
most rent with heat.
In some parts of Italy, it is remarked by that eminent physician and
philosopher, Dr James Johnstone, in his admirable volume, entitled the
Diary of a Philosopher, which, by the way, is a work of rare virtue, in
so much as it is replete, not only with accurate medical knowledge, but
with reflections in literature and the fine arts such as prove an
intimacy with polite learning not always found, that fever and that
general unwholesome state of body, observed in districts infested with
vitiated air, prevail where inquiry has discovered no appearance of
unusual dampness and corruption of the soil. He thinks that streams of
putrid water, containing animal and vegetable materials, that have sunk
down from the surface, in some part of their course are making their way
at a little depth, and that when the soil, parched with excessive heat
and drought, becomes rent, as it commonly does, the emanations
previously confined rush out by the channels now presented by these
fissures, and deal their deadly effects around.
Such an explanation seems to me highly probable, and deserving of more
inquiry. Connected with this subject, the following facts may be
interesting, and assist in forming an estimate of the probability of the
truth of that explanation.
In mines, as well as on the surface of the earth, changes are constantly
going on; and as in the latter situation the animal, vegetable, and
mineral components of the soil are decomposing, so the minerals in the
former are giving out some of their component parts and abstracting
oxygen, &c. in turn from the atmosphere.
In mines some of the fossils attract oxygen from the air, but the chief
process by which the atmosphere becomes vitiated there, is by the
evolution of gases from the minerals. In coal pits the principal gases
emitted are carbonic acid gas, commonly known as fixed air, which will
support neither animal life nor combustion, as proved by the disastrous
results on men having been confined in it, and by the extinction of
light when immersed therein, and carburetted hydrogen gas, known as
fire-damp, which cannot support respiration, and which takes fire when
brought in contact with a light. These gases are the results of chemical
changes going on in the minerals, in the same way as the gases before
alluded to attend the decomposition of animal and vegetable substances.
These gases arise not only from the minerals exposed to view at the
various surfaces, as the roof, sides, and pavement of coal pits, but
issue also from the unworked minerals in the interior, by fissures or
cracks in the various strata, produced by the violence used in detaching
the minerals.
These fissures extend in the course of the beds, or strata, and are
often scarcely visible, but are sometimes so wide as to admit the
finger. It is probable that they sometimes extend a considerable way
into the solid minerals.
In general, from these fissures there is constantly issuing streams of
gas, of a nature varying with the character of the minerals, but for the
most part they are such as have been mentioned. In the mines of Great
Britain, when the atmosphere above is much agitated, as by the
prevalence of southerly winds, and more especially if the violence
amounts to what is termed a storm, the gases pour out in prodigious
quantities, making a rushing noise, and filling the pit and excavated
parts. The pit then becomes so full as to interfere with the operations
of the men, who are frequently, for their safety, obliged to retire. In
this case the atmosphere is lightened, and the pressure it is constantly
exerting on all bodies with which it comes in contact is diminished, and
the consequence is, that the gases rush out, under the circumstances
already mentioned. It is known, that, during the prevalence of stormy
weather, the mercury in a barometer falls; it is for a like reason, the
weight upon it being less. Not only the gases issue from their caverns
when the air is thus lightened, but water contained in fissures in the
floor or pavement of mines rises also, sometimes to the amount of an
inch or two, and it is no uncommon thing to see the extrication of
vapour from a little collection of water on the floor, such as takes
place when water is boiling, a movement which it very much resembles.
These facts shew that it is not improbable that pestilential vapours,
ordinarily passing under the soil, may be extricated when fissures are
present. It may happen that effluvia may be prevented from issuing even
when fissures exist in the soil, from an increase in the weight of the
atmosphere, and in this way may be explained the occasional
disappearance of pestilence with a change of weather, not unfrequently
remarked in some tropical countries.
During the prevalence of strong north, north-east, and north-west winds,
blowing with considerable violence the currents in mines are
reversed—for, instead of gases issuing from the fissures and crannies,
currents of atmospheric air pour into them. These currents may be felt
with the hand, and the ear can detect the rushing sound; a flame applied
to a fissure is immediately drawn in, shewing the direction of the
current. These facts illustrate the influence which the state of the
atmosphere has upon terrestrial vapours.
As has been already observed, the exhalations from the soil obtain
different names from the effects they are wont to produce. When they
produce intermittent fever or ague, they are termed marsh miasms. When
they produce the various forms of malignant fever, such as the yellow,
the bilious fever of India, and the coast of Africa, simply pestilential
effluvia—and when they induce general bad health and degeneracy of the
inhabitants of a country, they are styled malaria, an Italian expression
signifying bad air.
As the subject appears one which may interest the general reader, it is
proposed to add a few observations on the diseases which are caused by
air vitiated with effluvia from the soil.