Water supplies : their purification, filtration, and sterilisation; a handbook for the use of local and municipal authorities / by Samuel Rideal and Eric K. Rideal.

  • Rideal, Samuel, 1863-1929.
Date:
1914
Catalogue details

Licence: In copyright

Credit: Water supplies : their purification, filtration, and sterilisation; a handbook for the use of local and municipal authorities / by Samuel Rideal and Eric K. Rideal. Source: Wellcome Collection.

    34/378 (page 18)
    products of fermentation, such as humic, crenic, aprocrenic and volatile acids. The liquid is commonly clear and organisms are few ; the brown tint with flat marshy taste and sometimes odour are general characteristics. Methods of treatment will be discussed later. (2) The water of marshes or swamps contains similar impurities, but is on the other hand generally turbid, foul smelling, and swarming with life. Although it is possible by habit to acquire immunity to both these classes of supply, they have a tendency to cause ague, dysentery, and a state to which the name paludism has been given (see ante). Deposits of Dead and Living Matter are apt to form in conduits, reservoirs, and cisterns, including hairs, epithelial scales, and even the entire dead bodies of small animals; wing scales of butterflies and moths, and parts of other insects. Fibres of clothing, sometimes dyed, may be identified under the microscope as silk, cotton, linen, or wool. Particles of muscular fibre when found in drinking water are considered to be evidence of contamination with faecal matter. Plant-hairs, pollens, spiral vessels, leaf epidermis, fragments of straw and seed-coverings (especially those of cereals), and of vegetables more or less discoloured from decomposition, may be also met with, as well as starches of various kinds. Microscopic examination of the sediment should therefore never be neglected. The Living Contents of Water comprise members of nearly all the natural families. Fish are a sign of fair aeration, because they disappear as a river becomes increasingly foul, owing to the absorption of the dissolved oxygen necessary for their breathing. But it must be remembered that fish in large numbers are often seen to congregate at the mouths of sewers where fmcal matter is visibly floating, being attracted by the insects and fragments of food carried down with the sewage. They are really more affected by muddy water and by chemicals from