in order to obtain the deepest col (ration the Blip must be protected from
too great velocity of the wind, especially when there is an excess of mois-
ture in the atmosphere."
\'i ii;im;i;\ is a colorless gas without taste or smell, rather lighter than
oommon air: its specific gravity being 0.972. It is slightly Boluble in
water, and distinguished by its apparent want of properties. Ir will
neither support life nor combustion. A burning taper is instantly ex-
tinguished in this gas, and an animal soon dies in it, not because I he gas is
injurious, but from the privation of oxygen. Yet it forms four-fifths of
the hulk of the atmosphere, and enters into the composition of all or-
ganic bodies â€” not, however, always found in vegetable substances,
though it is well known that no plant can attain maturity without the
presence of matter containing nitrogen. But no animal body which pos-
sesses motion is destitute of it. It is an essential element of food for all
the purposes of nutrition, and the chief ingredients of human blood con-
tain nearly seventeen per cent of nitrogen. Yet it seems to take no other
part in the functions of life than mere presence, the vital processes re-
quiring this, however, for their healthy exercise.
When the mysterious principle of life has ceased to exercise influence,
nitrogen assumes a peculiar activity, and becomes a promotor of death
and decay, by escaping from the elements which have held it in abeyance.
Its utility now becomes manifest. Nitrogen is emphatically the element
of death bound up with the life of the organism of every living being.
During life it is subject to the control of the vital forces, but no sooner
â– does life cease than nitrogen acquires a strong affinity with hydrogen,
and combining with it forms a new compound â€” ammonia. Oxygen is
thereby disengaged, and a new set of affinities begins, converting what
would otherwise be a state of rest into one of commotion and change.
Fermentation is excited, decomposition and oxidation proceed uninter-
ruptedly to a complete transformation of organic matter back again into
its original elements.
VAEIABLE CONSTITUENTS OF THE ATMOSPHERE.
AMMONIA, CARBONIC ACID, MOISTURE AND ELECTRICITY; AND
FLOATING MATTER IN THE AIR.
NATURE AND SOURCES OF AMMONIA â€” ABUNDANCE AND PROPERTIES
â€”INDICATIONS â€” PUTREFACTION AND ITS RESULTS â€” TESTS; CAR-
BONIC ACID: NATURE, SOURCES, PROPERTIES, DIFFUSION, DAN-
GERS AND TESTS OF; MOISTURE: QUANTITY AND PROPORTION IN
THE ATMOSPHERE AT TEMPERATURES â€” ABSOLUTE HUMIDITIES;
ELECTRICITY; FLOATING MATTER IN THE AIR.
Ammonia is a very light, colorless, gaseous compound, which con-
sists of one equivalent of nitrogen and three equivalents of hydrogen.
Its specific gravity or relative weight, when compared with hydrogen,
the lightest of all gases, is 8.5, or a little more than half that of the
weight of atmospheric air. It possesses a strong and pungent odor, fa-
miliar in spirits of hartshorn, and is distinguished as the volatile alkali.
It exists normally in the proportion of about three and a half volumes
in every 10,000,000 of atmosphere. In other words, in ten million gal-
lons of pure atmosphere, the amount of ammonia gas present is, on an
average, not more than three and a half gallons; though it frequently
exceeds this, and wherever it exists in excess it is suggestive of impure
Ammonia is exceedingly soluble in water, and cannot, therefore re-
main long in excess in the atmosphere, especially in rainy places, as
every shower of rain condenses it and conveys it to the surface of the
earth. Hence, rain-water always contains more or less ammonia, and it
is this which gives to rain-water the apparent sensation of softness gen-
erally experienced in its use.
In an address on " Air as a Sanitary Agent/' delivered to the Sani-
tary Institute of Great Britain, at Glasgow, in September, 1883, by Dr.
E. Angus Smith, the celebrated author of " Air and Bain," the follow-
ing practical remai'ks are made in regard to ammonia:
" When a room is shut up even for a day, unless the room be very
VARIABLE CONSTITUENTS OF THE ATMOSPHERE. 29
large indeed, there is always that peculiarity observed by sensitive per-
sons t<> which would be gives the came of closeness. X*e1 there are peo-
ple who do not seem to observe this, and whospend their lives in rooms
in which this closeness may he constantly observed. I have often re-
flected on this peculiar condition. Surely, if oxygen removed all impu-
rities, these impurities ought t<> have been removed, since the oxygen of
the air is never absent from the rooms, excepl to such a small extent thai
the estimation of the change is extremely difficult. It we lift up a win
dow and allow the air to blow into the room so as to entirely replace the
original air, we do not at all times attain efficient aeration. It takes hut
a few mimites, in a climate where there is considerable motion in the air,
to renew the atmosphere of a room entirely; we may judge of this by
making a trial upon a visible atmosjmere, viz., one pretty well-tilled with
smoke. AVe see how rapidly with an open window r every trace may
be removed from the farthest corner, and yet this new air is not suffi-
cient to refresh the room, and closeness is the characteristic still com-
plained of. It is the custom in well-regulated houses not to renew merely
the air, but to cause the air to blow through the house for a considerable
time every day when the weather permits it. Knowing this for a long
time, I wondered very much what was the reason. Surely, I said, there
was vital air enough without the long-continued current.
" Then the remarkable discovery of Schonbein came to my mind, as I
suppose it has to the minds of many other chemists, and I thought it
must be the ozone in the air that does the work, and as there is little
ozone in a volume, the air requires many repetitions of bulk. There
may be some truth in this still; but whether the air receives imperfect
contact with the substances to be purified, whether the mechanical ac-
tion of the current is necessary, or some other cause, it is certain that
a continual current is necessary for perfect purification. Looking fur-
ther at this subject, it occurred to me that really clean houses were pre-
served in this condition by something more tjian currents of air gene-
rally, and that good housewives resorted to the practical method of
rubbing by hand, and it seemed clear that no furniture could be preserved
from that peculiar condition of mustiness in any house where the doors
and windows must be frequently closed, unless the absolute removal of
certain substances from the surface were resorted to. And what was
this substance that required to be removed ? I suppose it to be one of
"If organic matter is everywhere, the presence of ammonia is every-
where possible; and if that matter is decomposing, ammonia is every-
where. That is the general statement which this paper illustrates. It
is now many 3'ears since it was observed by me that organic matter could
be found on surfaces exposed to exhalations from human beings: but it
is not till now that the full significance of the fact has shone on me,
and the practical results that may be drawn from it in hygiene and mete-
30 VARIABLE CONSTITUENTS OF THE ATMOSPHERE.
orology. These results are that ammonia may be an index of decayed
matter. The idea has been used partly and to a large extent â€” as illus-
trated in my ' Air and Eain ; ' the facts now to be given enable us to
claim for it a still more important place. The application seems to fit
well the conditions already examined; and by this means currents from
foul places have been readily found. This does not apply to the sub-
stances which may be called germs, whether it be possible to see them or
not, because they are not bodies which have passed into the ammoniacal
stage, although some of them may be passingâ€” those, for example, which
are purely chemical and exert what we may call idiolytic action.
"Ammonia must ever be one of the most interesting of chemical
compounds. It comes from all living organisms, and is equally neces-
sary to build them up. To do this, it must be wherever plants or ani-
mals grow or decay. As it is volatile, some of it is launched into the
air, on its escape from combination; and in the air it is always found.
As it is soluble in water, it is found wherever we find water on the sur-
face of the earth, or in the air, and probably in all natural waters, even
the deepest and most purified. As a part of the atmosphere it touches
all substances, and can be found on many; it is in reality universally on
the surface of the earth in the presence of men and animals, perhaps at-
tached more or less to all objects, but especially to all found within
human habitations, and we might also add, with equal certainty, the
habitations of all animals.
" If you pick up a stone in the city, and wash off the matter on the
surface, you will find the water to contain ammonia. If you wash a
chair or a table, or anything in the room, you will find ammonia in the
washing; and if you wash your hands you will find the same; and your
paper, your pen, your table cloth, and clothes all show ammonia; and
even the glass cover to an ornament has retained some on its surface.
You will find it not to be a permanent part of the glass, because you
require only to wash with pure water once or twice, and then you will
obtain a washing Avhich contains no ammonia; it is only superficial.
" This ammonia on the surface is partly the result of the decomposi-
tion, continually taking place, of organie matter adhering to everything
in dwellings. The presence of organic matter is easily accounted for;
but it is less easily detected than ammonia. It is probable that the
chief cause of the presence of ammonia on surfaces in houses and near
habitations is the direct decomposition of organic matter on the spot.
If so, being more readily observed than organic matter itself, it may be
taken as a test, and the amount will be a measure of the impurity. A
room that has a smell indicating recent residence will, in a certain time,
have its objects covered with organic matter, and this will be indicated
by ammonia on the surface of objects. After some preliminary trials,
seeing this remarkable constancy of comparative results and the beautiful
gradations of amount, it occurred to me that the same substance must
\ \i;i\i'.u: CONSTITUENTS OF THE LTMOBPHEBZ. 31
be found on all Bubjecta around us, whether in town <>r uot. I there-
fore wenl a mile from the outskirts of Manchester, and examined the
objects on the way. Stones thai not twenty hours before bad been
washed by rain showed ammonia. It is true that the rain of Mane!
fcer contains it also; but, considering that only a thin layer would be
evaporated from these stones, it was remarkable that they indicated the
existence of any. The surface of wood was examined; pailings, railic
branching of trees, grass (not very green at the time), all showed am-
monia in no very small quantities. It seemed as if the whole visibli
surface around had ammonia. 1 went into the houses and examined
the surfaces in rooms empty and inhabited, tables, chairs, walls, plates,
glasses, and drawing-room ornaments. A (Parian) porcelain statuette
under a glass showed some ammonia; a candlestick of the same material
(but uncovered) showed much more. The back of a chair showed am-
monia; when rubbed with a common duster, there was very little. It
seemed clear that ammonia stuck to everything.
" If, then, ammonia was everywhere, the conclusion seemed to be
that it was not at all necessary to do as I had been doing, namely, wash
the air so laboriously; it would be quite sufficient to suspend a piece of
glass, and allow the ammonia to settle upon it. For this purpose small
flasks were hung in different parts of the laboratory, and examined
daily. The flasks would hold about six ounces of liquid, but they were
empty, and the outer surface was washed with pure water by means of
a spray bottle; it was done rapidly, and. not above twenty cub. centim.
(two-thirds of an ounce) of water was used. This was tested for ammo-
nia at once with the Nessler solution. The second washing, taken imme-
diately, produced no appearance of ammonia. Ammonia could be
observed after an hour and a half's exposure at any rate; but I do not
know the shortest period.
" To me it seemed perfectly clear that the character of closeness was
connected with the existence of organic matter, and the organic matter
with the ammonia. That ammonia should be found almost everywhere,,
but in small quantities, was not to be wondered at, considering the uni-
versal presence of organic matter in the air and waters of the world. It
was when considering these things, the effect of oxygen on this organic
matter, that I came to the conclusion that a current of air either carried
away the organic matter with it, decomposing it and turning it into
gases, or, if it were not possible for oxygen alone to do this, it might
happen that the oxygen destroyed those minute forms which have been
shown to be concomitant with putrefaction and decay. . . .
" As putrefaction seems not to take place without the action of
organisms, I had the idea that it might be arrested by an abundant use
of air, and I had some belief that the oxidation took place very rapidly
after putrefaction. It was when examining this subject that I found it
necessary to touch also upon the question of nitration in water. When
32 VARIABLE CONSTITUENTS OF THE ATMOSPHERE.
nitrogenous bodies decompose with an abundance of oxygen, the nitro-
gen becomes oxidized, and nitric acid is formed. I had long suspected
the reverse also took place, and that when there was an excess of putre-
factive matter oxygen was absorbed, and even removed from the nitrate,
whilst free nitrogen was given off. This process I was able to verify by
carrying it into the laboratory. It was clear then, and beyond all cavil,
that rivers could purify themselves in time, and organic matter be thor-
oughly removed. It was clear that organic substances, that germs of
disease, that microbes, and the smallest organisms themselves were all
subjected to this universal and unsparing attack of putrefaction and
"Putrefaction destroys organic matter without the influence of oxy-
gen; it breaks up organic compounds, and destroys organisms. The
evidence seems to indicate that it destroys those bodies that j>roduce dis-
ease, but that in certain conditions it produces others. This is a point
not to be enlarged upon without more knowledge, but it is evident that
by putrefaction we get rid of an enormous amount of offensive matter.
Oxygen cannot enter under the surface of actively putrefying bodies;
but wherever it is allowed to enter by the putrefaction being less active,
an action begins which in time completes the destruction of the body.
"We are not therefore to suppose that the germs of disease can resist all
these efforts of nature to destroy noxious things, nor are we to suppose
that an invisible germ can pass from stage to stage unaffected by the
putrefaction of sewage and the action of air. "We must believe, for the
present, that it is not so. In water we see perfect putrefaction, nitrogen
itself being lost.
"In ordinary putrefaction sulphuretted hydrogen comes off in
abundance, with much carbonic acid and some nitrogen. Oxygen
resists this action, and if this action is applied in a concentrated condi-
tion a change takes place; nitrogen is evolved as the principal gas,
and a decomposition of nitrogenous compounds takes place. Nitro-
genous bodies are thus destroyed in one manner by their voluntary
putrefaction, in another by oxidation. . . .
<f Putrefaction and oxidation are two well-known modes of destroy-
ing organic bodies at ordinary temperatures. The second (oxidation) is
not proved to be connected with organisms. How far, then, can oxida-
tion, or a great supply of air, be employed to destroy putrefaction or to
" The bearing it has on the analysis of water will be clearly seen by
chemists. The bearing on the sewage question is also interesting. Sub-
stances and living things may be carried by the rapid sewage system
into the range of a new activity before undergoing the putrefaction
which breaks them up in proximity to us or in the sewers them-
selves. It seems to point to a plan of causing the destruction of organ-
isms by putrefaction and subsequent oxidation or chemical action. At
1 LBXABLS C0N8TMIIM- OF THE A.TM08PHXBE. 38
least it Beema to me that we require to learn if it be true that any of the
germs of disease, or which germs of disease, will lire in an abundance of
good air. We know that abundant dilution will render them all inef-
fective It IB probable thai there Will he a difference unionist them iii
this respect, whilst all will yield to the double aetion of, first, putrefac-
tion, and then oxidation. . .
"It has often been asked, what will become of those many poisonous
emanations which arise from the human body in health, and from those
still more dangerous substances which are generated within it during
many of the multifarious diseases to which man is subjected. The germ
theory of disease has caused alarm in many directions, and it has been
imagined that some little germ of disease passing into a sewer or pure
river might carry with it power to infect other organisms to such an
extent that there was reason to fear for the lives of all the inhabitants
on its banks. This extreme application of a theory might not be unrea-
sonable were it not that Ave know from results that no such power exist-
in any of those germs known to us.
" Let us consider the number of polluted liquids which pass from the
houses and hospitals of such a city as Glasgow, and the fact that so many
of its inhabitants go down to the banks of the Firth, towards which the
waters of the Clyde flow, and receive there health and strength for them-
selves and their families, and we shall see how absurd the ideas have been
concerning the power of individual germs, or even multitudes of germs in
such situations. . . .
"It is remarkable how rapidly sewage enters into putrefaction; and
to know the results of this putrefaction has been a considerable difficulty.
The gases from sewers have been found to produce a peculiar form of
fever, very well known to medical men in some of its stages, and appa-
rently so definite that it may be considered as ranking with one of the
chemical tests in its strictness. The gases which come from it are the
results of the decomposition of organic matter, and the number of com-
pounds into which the material of animals may be broken up is so varied
that at present it may be said to be entirely beyond our ken. These
â– compounds vary in character to such a degree that they may form the
most innocent gases, the most wholesome food, or the most virulent
poisons, venomous substances that destroy entirely vital functions of the
human body in a scarcely appreciable time. Some of these obnoxious
bodies arise from the decomposition of sewage, and, as already said, seem
to be formed at some particular proportion of the supply of air.
" It is easy to see that it is a mistake to suppose that by sending
putrefying liquids down to lands we are giving these lands all the sub-
stance which the sewage originally contained. If we wish to use them as
sewage it is better to use them before putrefaction, the loss by putre-
faction being great. I suppose we can scarcely doubt that putrefaction
34: VARIABLE CONSTITUENTS OF THE ATMOSPHERE.
takes place more rapidly when the organic matters are diluted to a very
considerable extent with water.
" Having made many experiments in order to find the condition of the
air found lying over somewhat solid putrid substances compared with the
same substances very diluted with water, it was found that the greatest
amount of ammonia and the most offensive odors were from the more
solid. This is quite in accordance with the explanation given of the more
complete disruption of the organic matter in water, and it was these
experiments that led me first to think of driving the air through sewage
matter in order to produce oxidation, expecting readily to form nitrates,
and in the belief also that the excess of air would be offensive to the
microzymes, although a small amount seemed necessary for their
activity. . . .
" The result of the aeration of sewages, and of other liquids containing
organic matter to a similar extent, was, that in all cases putrefaction was
delayed by aeration. The dissolved oxygen also recovers itself in the
aerated specimens better than in the non-aerated. This shows that
aeration not only prevented putrefaction, but prevented also the chemical
action consequent upon it. It had, in fact, to a large extent, and for a
considerable time, rendered the organic matter inert, or nearly so. Ni-
trates are formed also more readily in the aerated than in the non-aerated
" It was in looking for nitrates and measuring the amount of am-
monia in the aerated and non-aerated solutions that I observed how much
the ammonia diminished in amount, and sometimes the air passing out
from the water contained a strong smell of ammonia. The sewage was
tossed about, the volatile matter carried up with the currents of air, and
had no opportunity of returning. Work of a similar kind has been done
by Monsieur Lauth, which has been published in the Comptes Rendus,
where the following is stated:
" e It is well known that to obtain the ammonia from sewage has been
the aim of chemists for many years; and to make use of it in some form
or other without extracting it, has been the study of many engineers.
The amount of ammonia, as we have long known, is great in sewage, but
we have not known how to remove it. The amount, however great in
bulk, is small indeed in proportion to the amount of water, being from
four to seven grains, very often not more in a gallon of 70,000 grains.
The loss of ammonia, when using the apparatus described, suggested at
once a method of obtaining a revenue from sewage/
" The results obtained are far greater than those obtained by me, and
the product increase of ammonia by putrefaction is remarkably so.
" If we could only take one grain of ammonia out of one gallon sew-
age we should have from 1,000,000 gallons 1,000,000 grains: 142.8 lbs.,
let us say 140 lbs. Let us suppose there are in Glasgow flowing from
the sewers daily 50,000,000 gallons, and we should have 7,000 lbs. am-
VAKIAI.I.I i "N-IITDENTS <Â»!â€¢ llll. \ I M < Â».- 1 â– 1 1 I I: I .
monia daily, this would give as in a year above 1,100 tons, which might
be put down as somewhere nearly 660,000."
Such estimates as this serve to suggest the immense importance of
ammonia in the life of the world. It is by ammonia that plants every-
where are supplied with nitrogen â€” without which they cannot exist.
The) arc supplied chiefly from the atmosphere by the rain-, mists, and
dews; and by manures of all kinds whose value is in proportion to the
amount of ammonia they contain.
The amount of ammonia found in different waters is (in weight):
Fresh water (reservoirs, etc.) 0000003
Sea-water, from one to two grains* for every cubic foot. Trifling as
this quantity appears to be, when we reflect that the ocean covers more
than three-quarters of the globe, and consider its enormous mass, it may
be looked upon as the vast reservoir of ammonia whence the atmosphere
can make good the losses which it is continually undergoing.
M Desfontains, a distinguished French engineer, some years ago
estimated the amount of ammonia carried down to the sea by the Rhine.
He computed that the Rhine at Lauterburg has, on the average, a flow of
39,000 cubic feet of water a second. From a careful analysis of the water,
in its passage by Lauterburg, it carries down with it every twenty-four
hours at least 22,500 lbs. of ammonia â€” that is, 13,000,000 lbs. a year. Tak-
ing this estimate as a fair example of the amount of ammonia poured
into the sea by the rivers of the world, in proportion to the volume of
the water-flow severally, the mind fails to comprehend the magnitude of
the amount of ammonia and the waste of agricultural wealth poured into
the sea by the outfall of sewers.
Minute traces of free ammonia or ammonium compounds may be de-
tected: (1) by Nessler's solution â€” an alkaline solution of potassium-