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passengers at the time. The temperature was 66° F., and the barometer on the platform stood
at 30.3 inches. The carbon dioxide in the air was .09 per cent., and the organic matter .0019.
Immediately afterwards two similar fresh-air samples were taken from a scaffold in
Newgate-street, over the station at a height of some 50 feet above the level of the street, well away
from any obvious source of contamination. It was a fine, dry day, slightly cloudy, with a light
S.W. wind. Temperature 55° F., barometer 30.17 in. The carbon dioxide in the air amounted to
.038 per cent., and the organic matter was .0020.
The numbers of bacteria and other organisms found after incubation was as follows—
Railway air.—Five litres incubated in gelatin at 20° C. yielded 27 colonies. These
were made up of 14 bacteria, 1 streptothrix, 3 yeasts, and 9 moulds.
Five litres incubated in agar-agar at 37° C. yielded 7 colonies, all bacterial.
The following species were identified in this 10 litres of air—Micrococci: Sarcina
lutea, sarcina alba, staphylococcus epidermidis albus, staphylococcus cereus albus, staphylococcus
cereus flavus, micrococcus cremoides, micrococcus citreus, micrococcus versatilis.
Bacilli: B. mesentericus vulgatus, B. lactis innocuus, B. helvolus, B. latericius, and a
non-pathogenic pseudo-diphtheria bacillus. Yeasts: Saccharomyces cerevisise and torula
alba liquefaciens. Streptothrix: Str. albido-flava. Moulds: Penicillium glaucum,
aspergillus glaucus, aspergillus flavus, aspergillus fumigatus, and aspergillus niger.
Fresh air.—Five litres incubated in gelatin at 20° C. yielded 60 colonies, made up of
34 bacteria, 1 yeast, and 25 moulds. Five litres incubated in agar-agar at 37° C. yielded
five colonies, consisting of two bacteria, one streptothrix, and two moulds.
The following species were identified in this 10 litres of air—Micrococci: Staphylococcus
epidermidis albus, staphylococcus cereus flavus, M. cremoides, M. orbicularis, M.
citreus, M. lactis, and a species of coccus undetermined. Bacilli: B. mesentericus vulgatus,
B. helvolus, B. lactis innocuus, and B. arborescens non-liquefaciens. Yeasts: An oïdium,
of which the exact species could not be determined. Streptothrix: Str. chromogenes.
Moulds: Mucor mucedo, penicillium, glaucum, aspergillus fumigatus, niger and glaucus.
II.—On March 17th similar samples were taken at 11.45 a.m. in one of the lifts at the Post
Office-station. It made six or seven journeys up and down while the samples were being taken,
carrying only a moderate number of passengers. The temperature in the lift was 61° F., and the
average barometric pressure 30'52 in. The carbon dioxide in the air was .109 per cent., and the
organic matter .0028.
Fresh air samples were then taken in the public garden behind the Post Office buildings,
known as the “Postmen's Park." The samples were taken on a quiet seat, close to Little Britain,
about two feet from the ground. Hardly any people were in the garden. It was a cloudy, dull
day, with a light W. wind. No rain had fallen for two days. The temperature was 57° F., and
the barometer 30.5 in. The carbon dioxide in the air was .043 per cent., and the organic matter
0024.
The following were the results after incubation—
Lift air.—Five litres, incubated in gelatin at 20° C., yielded 39 colonies made up
of 20 bacteria, 5 yeasts, and 14 moulds.
Five litres incubated in agar-agar at 37° C. yielded six colonies, of which one was a
mould and the rest bacteria.
The following species were indentified in this 10 litres of air—Micrococci: Sarcina
lutea, sarcina alba, staphylococcus pyogenes albus, staphylococcus cereus albus and flavus,
M. candicans, M. citreus, and M. lactis. Bacilli: B. mesentericus vulgatus. Yeasts:
Saccharomyces cerevisiae, torula alba, and a species of oidium. Moulds: Penicillium
glaucum, aspergillus fumigatus, and two undetermined species.
Fresh air.—Five litres incubated in gelatin at 20° C. yielded 27 colonies made up of
23 bacteria and four moulds.
Five litres incubated in agar-agar at 37° C. yielded eight colonies, all of them
bacterial.
The species identified from this 10 litres of air were as follows—Micrococci: Sarcina
lutea, sarcina alba, M. cremoides, M. citreus, M. candicans, and M. lactis. Bacilli
B. luteus, B. lactis innocuus, B. xerosis, B. domesticus, and two undetermined species.
Mould: Penicillium glaucum.
III.—On March 21st similar samples were taken at 11.45 a.m. in a smoking carriage full
of passengers, between the Bank and British Museum stations. The temperature in the carriage
was 70° F., and the barometer stood at 29'57 in. The carbon dioxide was 108 per cent, and the
organic matter '0026.
The fresh air samples were taken at 12.15 p.m. on the roof of the school buildings of St.
Bartholomew's Hospital, about 100 feet above the ground. It was fine, after much rain on the
previous day, and there was a brisk S.W. wind. The temperature was 50° F., and the barometer
stood at 29.4 in. The carbon dioxide was 045 per cent., and the organic matter 0011.
The results were as follows—
Air of smoking carriage.—Five litres, incubated in gelatin at 20° C., yielded 61
colonies, viz., 51 bacteria, 1 yeast, and 9 moulds.
Five litres incubated in agar-agar at 37° C. yielded seven colonies, all bacterial.
From this 10 litres of air the following species were identified—Micrococci: Sarcina
lutea, sarcina alba, staphylococcus cereus albus and flavus, micrococcus rosettaceus,
M. lactis, M. cremoides, M. citreus, M. orbiculatus, and two undetermined species.