634 TRANSACTIONS OF SECTION I. 
a man weighing 60 kilogrammes. No proper controls were carried out. It is 
recognised now that any distilled water contaminated by bacterial products may 
have a toxic effect. Flack and I have for fourteen weeks kept guinea-pigs and 
rats confined together in a box and poorly ventilated, so that they breathed air 
containing 0°5 to 1°0 per cent. of CO,. The guinea-pigs proved wholly free trom 
anaphylactic shock on injecting rats’ serum. Therefore they were not sensitised 
by breathing the exhaled breath of the rats for many weeks, and we are certain 
that no foreign protein substance is absorbed in this way. It has been proved by 
others, and by us, that animals so confined do well so long as they are well fed 
and their cages kept clean, light, cool, and dry. It is wholly untrue that they 
are poisoned by breathing each other’s breath. The only danger arises from 
droplet contagion in cases of infective disease. 
To study the relative effect of the temperature and chemical purity of the 
atmosphere I constructed a small experimental chamber of wood fitted with large 
glass observation windows and rendered air-tight. 
On one side of the chamber were fixed two small electric heaters, and a tin 
containing water was placed on these in order to saturate the air with water 
vapour. On another side of the chamber was placed a large radiator through 
which cold water could be circulated when required, so as to cool the chamber. 
In the roof were fixed three electric fans, one big and two small, by means’ of 
which the air of the chamber could be stirred. The chamber held approximately 
3 cm. of air. In one class of experiments we shut within the chamber seven or 
eight students for about half an hour, and observed the effect of the confined 
atmosphere upon them. We kept them until the CO, reached 3 to 4 per cent., 
and the oxygen had fallen to 17 to 16 per cent. The wet-bulb temperature 
rose meanwhile to about 80° to 85° F., and the dry bulb a degree or two higher. 
The students went in chatting and laughing, but by-and-by, as the temperature 
rose, they ceased to talk and their faces became flushed and moist. To relieve 
the monotony of the experiment we have watched them trying to light a cigarette, 
and, puzzled by their matches going out, borrowing others, only in vain. They 
had not sensed the diminution of oxygen, which fell below 17 per cent. Their 
breathing was deepened by the high percentage of CO,, but no headache occurred 
in any of them from the short exposure. Their discomfort was relieved to an 
astonishing extent by putting on the electric fans placed in the roof. Whilst the 
air was kept stirred the students were not affected by the oppressive atmosphere. 
They begged for the fans to be put on when they were cut off. The same old 
stale air containing 3 to 4 per cent. CO, and 16 to 17 per cent. O, was whirled, 
but the movement of the air gave relief, because the air was 80° to 85° F. (wet 
bulb), while the air enmeshed in their clothes in contact with their skin was 
98° to 99° F., wet bulb. If we outside breathed through a tube the air in the 
chamber we felt none of the discomfort which was being experienced by those 
shut up inside. Similarly, if one of those in the chamber breathed through a 
tube the pure air outside he was not relieved. 
R. A. Rowlands and H. B. Walker carried out a large number of observations 
in the chamber, each acting as subject in turn. 
They recorded the effect on the respiratory ventilation and on the pulse rate 
both when resting and when working. The work consisted in pulling a 20-kilo. 
weight about one metre high by means of a pulley and rope. 
In some of the experiments the exhaled carbonic acid was absorbed, and in 
others carbonic acid was put into the chamber. The subjects inside could not 
tell when the gas was introduced, not even if the percentage were suddenly 
raised by two. The introduction of this amount of the gas made no sensible 
difference to them, but increased their pulmonary ventilation. 
In every one of the experiments they suffered from the heat, and the putting 
on of the fans gave great relief, and in particular diminished the pulse rate 
during and after the working periods. The relief became much greater when 
cold water was circulated through the radiator and the temperature of the 
chamber lowered 10° F. 
The subjects wore only a vest, pants, and shoes in most of these experiments. 
When they wore their ordinary clothing the effect on the frequency of the pulse 
was more marked and the discomfort from heat and moisture much greater. 
I have made observations on men dressed in the Fleuss rescue apparatus for 
