ON THE CARBONIC ACID, ORGANIC MATTER, ETC., IN AIR. 
83 
other respects similar to the boys’ room, which was lighted by windows (open) and 
had only half as much space per person as the girls’ room. 
In ten pairs which could be compared for carbonic acid eight were very largely in 
favour of the girls, whilst in one of the two exceptions the girls were only very slightly 
in excess of the boys. As regards the oxidisable organic matter, there were, out of 
nine pairs which could be compared, six largely in favour of the girls, whilst of the 
three exceptions two were only slightly in excess of the boys. With two exceptions, 
out of ten pairs of rooms compared, the temperature with the girls was always lower 
than with the boys. 
The average results are given in the following Table :— 
Space per 
person. 
Tempera¬ 
ture. 
(° Fair.) 
Carbonic 
Acid. 
Organic 
matter. 
Micro-organisms. 
Total. 
Bacteria. 
Moulds. 
No. of rooms compared . 
30 
20 
20 
16 
30 
30 
30 
Boys. 
275 
60 
15-0 
7-9 
92 
90 
2 
Girls. 
382* 
58 
12-3 
67 
65 
64 
1 
It is thus seen that boys tend to make the air of a room more impure than girls do, 
and that consequently they require a more efficient ventilation in order to maintain 
a given standard of purity in the air of their rooms. The reasons for this are not far 
to seek, and may be stated as follows :—(1) The boys are more restless, and so raise 
more dust, which necessarily contains micro-organisms (see below). For the same 
reason they evolve more carbonic acid, and probably organic matter. (2) The girls 
are, as a rule, cleaner, and this has a marked effect (as will be shown below) in dimi¬ 
nishing the number of micro-organisms. (3) Boys usually come to school after more 
violent exercise than girls, which results in the production of more carbonic acid, and 
probably of organic matter (see below). (4) From differences in constitution, more or 
less apart from the above reasons, boys evolve more carbonic acid, and perhaps 
of organic matter (see Parkes’ ‘Hygiene,’ 6th edn., p. 114). Or, to sum up some of 
the above reasons, and put them from a slightly different point of view, boys eat more 
than girls. 
The Air of Mills and Factories. 
We have only examined four of these, samples having been taken from two rooms 
in each. As the results obtained differ very widely in the several cases, we are not 
* This cubic space in favour of the girls is caused by the space per person in one of the rooms being 
very much larger than in any other. 
M 2 
