66 
PROF. T. CARNELLEY, MR. J. S. HALDANE, AND DR, A. M. ANDERSON 
Dundee (town, quiet places.) 
Dundee (suburbs). 
Perth (outskirts). 
No. of 
No. of 
No. of 
determi¬ 
nations. 
Lowest. 
Highest. 
Mean. 
determi¬ 
nations. 
Lowest. 
Highest. 
Mean. 
determi¬ 
nations. 
Lowest. 
Highest. 
Mean. 
Carbonic acid 
32 
2 2 
5-6 
3-9 
5 
1-8 
3-5 
2-8 
3 
2-9 
3-5 
3-1 
Organic matter . 
Total micro- 
46 
1-7 
16-8 
8-9 
10 
0 
5-6 
2-8 
5 
1-7 
4*5 
3-1 
organisms:—* 
15 
0 
2-2 
0'8 
1 
, , 
• . 
0-1 
,, 
, . 
.. 
. . 
Bacteria. . 
14 
0 
1-9 
0-6 
1 
. . 
, . 
0 
, . 
t , 
. . 
Moulds . . 
14 
0 
1-3 
0-2 
1 
• * 
• * 
o-l 
* * 
• • 
The above Table shows —(1) That the average carbonic acid and organic matter 
were much lower in suburban than in town air. Presumably they would be still less 
in country air. No conclusion can be drawn as regards the relative proportion of 
micro-organisms in town and suburban air, as only one determination was made in the 
latter case. (2) That this difference is relatively much greater in the case of the 
organic matter than in that of the carbonic acid. (3) That the quantity of organic 
matter, at least in town air, varies within much greater limits than that of the 
carbonic acid. (4) That the average number of micro-organisms in town air was 
rather less than one per litre for town air in Dundee in winter. (5) That the number 
of bacteria in the air of quiet places in winter in Dundee was about three times as 
great as the number of moulds. In the open streets during dry and windy weather 
the proportion of bacteria is much greater (see pages 99 (Table) and 101). 
The numbers of which the above are the means exhibited variations of every degree 
within the limits shown in the Table. Some of the causes of these variations w ill 
appear from the following Tables. 
Influence of Day and Night, and of Open and Closed Places. 
This is clearly shown in the Tables given below. The day has been supposed to 
extend from 5 a.m. to 7 p.m., as these are about the hours at which work begins and 
ends at the mills and factories in Dundee. Although the ordinary work begins at 6 A.M., 
the boiler tires, &c., begin to smoke about 5 a.m. By “ open places ” we mean ordinary 
streets, large yards, squares, &c. ; whilst by “ close places ’ are meant narrow lanes, 
entries, back-yards, and other places closely surrounded by houses, and more especially 
by crowded low-class houses. No determinations were made in close places during the 
day. 
* A larger number of micro-organisms (11 per litre on an average) were found at places in or close to 
open streets on which there was much traffic (see page 99, Table). These observations were made in 
April and May, 1886, and subsequently to those detailed above. 
All the observations included in the above Table were made with ten litres of air. 
