Volume 2

A Textbook of the theory and practice of medicine ... / edited by William Pepper.

Date:
1893-94
Catalogue details

Licence: Public Domain Mark

Credit: A Textbook of the theory and practice of medicine ... / edited by William Pepper. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    47/938 (page 29)
    As the soil water is constantly in motion, and for each locality this motion is tolerably uniform in direction and velocity, it follows that in privy-well and cesspool villages and towns it may be much more contaminated in one part of the town than in another. Nearly every form of micro-organism may be found in the soil at different places and times, and their number and character depend on the moisture and temperature and on the presence of suitable food material. From the sanitary point of view the most important of these are the Plasmodium malaria?, the bacillus of typhoid, of tetanus, of anthrax, of tuberculosis, of diphtheria, and of cholera, and the nitrifying organisms. The pathogenic micro-organisms or their products may pass into the soil water, being washed down by rainfall, or into the air with particles of the surface soil blown about as dust. They cannot be drawn far through soil by air-currents, especially if the soil is slightly moist. To prevent ground air and dampness from entering the cellars of dwelling- houses, the floor, and the sides of the cellar up to ground level, should be laid with bricks soaked in asphalt. A cement floor is quite pervious to air when it becomes dry. In low sites, and especially in malarious regions in warm climates, it is better to have no cellar beneath the house, which should be raised on piers, posts, or arches. The natural processes for the purification of soil containing much organic matter of animal origin, such as the made ground in the suburbs of cities or the ground in the vicinity of leaky cesspools or of graves, is a slow one, requiring from three to eight or more years, according to the porosity of the soil and the accessibility of fresh air to the interstices. Hence, when a system of sewerage is introduced in a city which has previously been storing up its filth in cesspools, it requires some time for the nitrifying organisms to complete the work of purifying the polluted soil. Water-Supply. Water is sometimes considered as a food, because it is taken into the body through the alimentary canal, but it supplies no force for the production of either heat or motion. It is, however, the universal medium in and through which the processes of life occur and the products of vital action are removed and excreted. 58 per cent, of a man's body is composed of water; he must have from 60 to 90 ounces a day in his food and drink to maintain his weight and strength, and he needs a much larger quantity externally to keep his skin and his morals in good condition. In a fairly cleanly household the average necessary consumption of water per head per day is from 10 to 15 gallons. For all purposes the water-supply of a town should not be less than 18 gallons per head per day; if it is used freely and none is wasted, it will require about 25 gallons per head per day. The average supply in the larger American cities is more than three times this, the greater part being wasted through leaky fixtures. This constant use of water by every living being makes the quality of the water used of great importance, as it is very liable to contain matters injuri- ous to health. The most important of these are the micro-organisms which