Volume 1
A system of medicine by eminent authorities in Great Britain, the United States and the Continent / edited by William Osler, assisted by Thomas McCrae.
- Date:
- 1907-10
Licence: In copyright
Credit: A system of medicine by eminent authorities in Great Britain, the United States and the Continent / edited by William Osler, assisted by Thomas McCrae. Source: Wellcome Collection.
Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.
94/986 (page 70)
![The action of humidity on the organism is very important from the standpoint of respiration and the function of the skin. In dry and warm air the cutaneous evaporation is very active; in dry and cold air the pul- monary evaporation is stimulated. The humid and cold air presents this inconvenience, that by diminishing cutaneous evaporation and increasing the loss of heat from the surface of the body, it predisposes to catarrhal affections, to renal diseases, and to rheumatism. The humid and cold air diminishes the cutaneous evaporation, and when perspiration is not evaporated the variations in the temperature are apt to cause diseases which are usually attributed to cold. Besides, the appetite and metab- olism in general suffer and disable the affected individuals for any work; intestinal diseases develop easily, and pulmonary tuberculosis finds a favorable condition for its rapid development. Moist and warm air has a special affinity for organic matter, and therefore predisposes to develop- ment of pathogenic organisms, which makes the surrounding atmosphere insalubrious. If the inhalation of impure air is prolonged or constant, as, forexample, in unclean dwellings, etc., malnutrition and anaemia, with gastro-intestinal disorders, will be the consequence. These factors play a predisposing role in pulmonary diseases, especially in tuberculosis. Sewer air is charac- terized by diminution of oxygen and increase of carbon dioxide (more so in summer), and association of ammonia compounds with hydrogen sul- phide. All these elements are undoubtedly obnoxious, but what par- ticularly makes the sewer air unwholesome is the association of organic matter, Avhich is an excellent carrier of pathogenic microbes. It is readily understood that some infectious diseases may be directly traced to this origin, especially during epidemics. The disturbance in the proportion of the normal constituent elements of air is observed not only in association with organic material subject to putrefaction, but also in changes of atvwspheric pressure. In normal con- ditions there is an antagonism between the internal pressure and the pres- sure produced by the surrounding atmosphere. Equilibrium is maintained when one counteracts the other; but should local atmospheric disturb- ances make their appearances, air pressure is felt. We have seen above that oxygen is indispensable for life, and the purity of air is judged by the presence of a sufficient amount of this gas. If oxygen is conducive to health, it may under certain conditions become obnoxious and cause a pathological state. The latter is precisely ob- served in changes of atmospheric pressure. Paul Bert says pure oxygen may act as a poison, and animals die in ordinary air when pressure of O falls to 3.4 per cent, of atmosphere, while in superoxygenated air they die when pressure of CO2 rises to 25 ]ier cent, of atmosphere. In order to collect facts regarding the effect of various degrees of air pressure on human life, investigators employed the method of balloon-travel. The first trip was made in Paris in 1875, by Spinelli, Sivel, aiid Tissandier. They rose to a height of 7,000 meters. At that level they felt a constantly increasing weakness and apathy until they reached a complete absence of power of motion, although their mentality remained unchanged. Soon they could not use their tongue for speaking. At the height of 8,000 meters they all lost consciousness. Tissandier regained consciousness and survived, while the other two perished. The principal facts noted in](https://iiif.wellcomecollection.org/image/b24907212_0001_0094.jp2/full/800%2C/0/default.jpg)
