TRANSACTIONS OF SECTION I. 543 



1 find that while raising the percentage of C0 2 suddenly from one to two per 

 cent, has no appreciable effect in increasing the discomfort, putting the fans 

 on or off makes a very great difference. The stationary air entangled between 

 the bodies of the men becomes warmed to body temperature and saturated 

 with moisture at body temperature. They cannot lose heat by radiation to 

 each other. The skin becomes warm, flushed, and bathed in sweat. Putting 

 on the fans whirls the air round and brings the cooler air (at 85° F.) in contact 

 with the body, and so promotes loss of heat by evaporation of the sweat and 

 convection. Benedict has kept men for twelve days in his calorimeter with a 

 very deficient ventilation current. So long as the chamber was kept cool they 

 kept in health and comfort, worked hard, and had no sense of closeness. 



Carrying out a series of work experiments in our chamber with Messrs. 

 R. A. Rowlands and H. B. Walker, I find the pulse frequency is more acceler- 

 ated during the work and takes longer to slow down again when the fans are off 

 than when they are on. The pulse frequency depends on the wet-bulb temperature, 

 and the C0 2 percentage makes relatively little difference to it. The breathing 

 volume, or. the other hand, depends chiefly on the C0 2 percentage. 



(ii) Ventilation in Confined Quarters. By Professor N. Zuntz. 



Dr. Leonard Hill in his introductory remarks refutes the idea of the harmful 

 action of carbonic acid up to three or even four per cent, of the atmosphere, and 

 he also attributes no importance to any substances exhaled by the organism to- 

 gether with the carbonic acid. I can agree with this view in so far as the great 

 number of positive data on the poisonous action of the exhaled products of 

 living animals is opposed by excellent experiments in which no sort of noxious 

 effect could be demonstrated. This innocuity seems well proved for man by 

 the experiments of Benedict in Atwater's respiration calorimeter. On the other 

 side, noxious effects have been stated in guinea-pigs — that means in animals 

 whose bowels are the seat of intense fermentations. The idea that the pro- 

 ducts of those fermentations may be poisonous in some cases is supported by 

 the fact that there exist diseases in man which are considered as caused by 

 poisonous substances absorbed from the intestines. Why may not one or an- 

 other of those poisons be volatile, as SH 2 is? Moreover, one may object against 

 the conclusiveness of Benedict's experiments, that he circulates the air of his 

 chamber through great vessels containing concentrated S0 4 H,. This acid may 

 destroy the volatile toxins of the air and 60 keep their quantity on a low 

 innocuous level. 



For some years I have considered in my lectures on the hygiene of domestic 

 animals the prevention of excessive moisture of the air in stables as the most im- 

 portant aim of ventilation. But I have not only had in mind that special point, 

 the importance of which Dr. Hill has explained so clearly — that is, the prevention 

 of a sufficient cooling of the body when the evaporation from the skin i« inter- 

 fered with by the saturation of the air with vapour. As soon as the air is 

 saturated there begins a condensation of water at the cooler parts of the walls. 

 This condensation obstructs the capillary pores of the walls and diminishes 

 the ventilation through them. So the removal of moisture is interfered with 

 more and more, and a vegetation of bacteria and mould sets up in the walls and 

 produces noxious gases and vapours. The same thing often happens in newly 

 built houses, when they are inhabited before the hydrate of lime has been 

 changed into carbonate. 



If we ask, now, how to provide for the ventilation of a room to prevent 

 the condensation of vapour, we may make the following calculation. A man 

 excretes in twenty-four hours in minimo 800 gr. C0 2 and 1,000 gr. H,0 vapour, 

 that means at a pressure of 760 mm. =400 litres C0 2 and 1,200 litres H 2 0. If the 

 ventilation would keep the content of C0 2 in the confined air as low as 0-3 per 

 cent., the quantity of vapour added to the moisture of the entering fresh air 

 would be one per cent., that is 7'6 mm. tension of the vapour. This added to 

 that of normal outside air of medium temperature would bring its humidity near 

 the point of saturation. So we understand that the limit of CO, content, 

 which Pettenkofer empirically found to be consistent with the feeling of 

 euphoria of the inhabitants of a room, is really that limit at which the danger 

 of condensation of water at the walls begins. 



