July 16, 1870.] 
THE PHARMACEUTICAL JOURNAL. 
41 
THE CHEMISTRY OF THE ATMOSPHERE. 
BY J. ALFRED WANKLYN. 
A first glimpse at the minute but potent constitu¬ 
ents of tlie atmosphere, is afforded by Dr. Angus 
Smith’s reports under the Alkali Act passed in the 
year 1863. As is doubtless known to many of our 
readers, it is the business of the Government In¬ 
spector under tliis Act to take upon himself the office 
of Conservator of the Atmosphere in the manufac¬ 
turing districts, and in the discharge of his duty the 
Inspector has had before him the task of distin¬ 
guishing between polluted and non-polluted air. 
His results, especially those just published in the re¬ 
port for the year 1869,* appear to us to be of the 
highest interest. 
That the air of a close room is different from the 
air of a well-ventilated room; that air indoors is 
different from air outside ; that the air of a town is 
different from the air of the country, and that the 
air of one country-place is not quite the same as the 
air of another country-place,—all tliis is matter of 
common observation. But wherein these differences 
consist has been, up to the present time, involved in 
the greatest obscurity, and is now, for the first time, 
becoming intelligible. 
Towards the close of last century, immediately on 
the discovery of the mam composition of the atmo¬ 
sphere, viz. that it consisted of a mixture of nitrogen 
and oxygen, and that the important processes of 
combustion and respiration consisted in chemical 
action of the latter on the combustible burnt or on 
the tissues of the animal which breathed,—the idea 
arose that the differences between one atmosphere 
and another depended on richness or poorness in 
oxygen. Tliis idea, in itself so plausible, was fos¬ 
tered by the irregular character of the analytical 
results furnished by the method of analysing air, 
which was in vogue at that early period in the his¬ 
tory of chemical analysis. 
Many of these early measurements of the quantity 
of oxygen in the air were made by observing the 
contraction which a volume of air underwent when 
subjected to the action of nitric oxide. Very accurate 
results are possible when this process is properly 
performed (Cavendish got excellent results with it), 
but sources of error, which we understand at the pre¬ 
sent day, though they were not understood when it 
•was in use as an analytical process, prevented the 
general attainment of accurate results at that period. 
Thus it was that great variations in the proportion 
of oxygen in the atmosphere were regarded as having 
been found by chemical analysis, and to this source 
may be traced those curious errors which have sur¬ 
vived to the present day in the discourse of the 
itinerant lecturer, and even of the medical practi¬ 
tioner (in foreign countries as well as at home) who 
opens the window to let in oxygen , and is oppressed 
by the excessive accumulation of carbonic acid. 
With the modern improvement in the methods of 
eudiometric analysis, the truth became apparent, that 
the proportion of oxygen in the air is very nearly con¬ 
stant,—Regnault, Bunsen, and all modem chemists 
who have examined the composition of the atmo¬ 
sphere, being unanimous on this point. The following 
determinations may be quoted:— 
* Sixth Annual Report of the Inspector under the Alkali 
Act of 1863. London: Eyre and Spottiswoode. 
Third Series, No. 3. 
Oxygen per cent. 
Air from sea-sliore, Scotland .... 
„ the summit of hills, Scotland 
„ suburb of Manchester . . . 
75 55 ... 
„ St. John’s, Antigua .... 
„ a close sitting-room .... 
„ pit of a theatre, 11 p.m. . . 
2 Feb. 1866. Court of Queen’s Bench . 
The air of a crowded room therefore contains very 
nearly as large a proportion of oxygen as the air of 
the open country. Furthermore it lias been shown 
that great variation in the proportion of oxygen may 
be made without any corresponding physiological 
effect being produced on animals breathing such an 
atmosphere. 
For the essential distinctive characters of different 
atmospheres we camiot, therefore, look to the relative 
percentages of oxygen in different specimens of air, 
but must look to other criteria. In truth, the sanitary 
chemistry of the atmosphere is very much like that 
of water; being, like the latter, concerned with very 
small quantities of impurities present in very large 
quantities of the main material. Pursuing tliis 
analogy, which may be of service in conveying a 
just idea of the character of atmospheric impurities, 
the carbonic acid present in air may be likened to 
the total solids contained by waters. In 100,000 
volumes of average air there are about 34 volumes 
of carbonic acid. In 100,000 parts of average Thames 
water, as supplied to the metropolis by the water 
companies, there are about 28 parts of total solid 
residue. Moreover, the slight percentage of carbonic 
acid hi the air is just as harmless as the main bulk 
of the total solid residue of water, and the extent of 
variation which actually obtains in the amount of 
carbonic acid in badly ventilated rooms is quite too 
small to be of physiological importance. 
The following numbers will serve to give an idea 
of the actual quantities of carbonic acid which occur 
in different specimens of air. 
100 volumes of air Vols. of C0 2 . 
From the hills in Scotland contain 0'0332. 
From surface of Thames (London) 0 0343. 
Neighbourhood of middens contain 0'0774. 
Worst parts of theatres „ 0'3200. 
The proportion of carbonic acid in the worst of 
these specimens of air, and probably a far higher 
proportion of carbonic acid, would be without physio¬ 
logical importance. 
It is not the carbonic acid, but matter existing in 
air in far smaller quantity, which determines the 
physiological character of different atmospheres. 
Referring to the report just issued, it will be seen 
that Dr. Angus Smith has recognized atmospheric 
pollution by acids, salts, and nitrogenous organic 
matter, the latter having been detected and measured 
by the ammonia-process.* The absence of vegeta¬ 
tion in the northern manufacturing towns, and in the 
neighbourhood of many kinds of chemical works, is 
ascribed, in great part, to the presence of free acids, 
such as sulphuric and hydrochloric in the atmo¬ 
sphere ; and the possibility is suggested, that to the 
presence of traces of different saline substances in 
the air of seaside watering places, may be due some 
of the sanitary effects wliich attend a sojourn in 
places of that description. 
* Journal of Chemical Society, 1867, vol. v. p. 445. 
20-999 
20-980 
20-980 
20-960 
20-950 
20-890 
20-740 
20-650 
