A manual of practical hygiene / by Edmund A. Parkes ; edited by F.S.B. Francois de Chaumont.

Date:
1878
Catalogue details

Licence: Public Domain Mark

Credit: A manual of practical hygiene / by Edmund A. Parkes ; edited by F.S.B. Francois de Chaumont. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    15. Water from Wells near the Sea*—This often contains so much saline matter as to taste quite brackish, although the organic matter may not be very large. In some samples from Shoeburyness (analysed at Netley) the ] total solids ranged from 104 to 218 grains per gallon of total solids, the chlorides being from 22 to 65 : mean of six samples—165 total solids, and 35 of chlorides. In one sample, however, the albuminoid ammonia was only 0-07 per million, and in five the oxygen required for organic matter was under 075 per million. 16. Bain Water may be contaminated by washing the air it falls through, but more by the surface on which it falls, such as decaying leaves or other matter on the roofs of houses j it also takes lead from lead coatings and pipes, and zinc from zinc roofs. 2. Impurities of Transit from Source to Reservoirs. Open conduits are liable to be contaminated by surface Avashings carrying in finely divided clay, sand, chalk, and animal matters from cultivated land ; and the leaves and branches of trees add their contingent of vegetable matters. These impurities may occur in most cases, but in addition the refuse of houses, trades, and factories is often poured into rivers, and all sorts of matters are thus added. These impurities are broadly divided by the Eivers Pollution Commis- sioners into sewage and manufacturing; under the former term all solid and liquid excreta, house and waste water, and in fact all impurities coming from dwellings are included; under the latter term are placed all manufactur- ing refuse, such as from dye and bleach works, tanneries, paper-making, woollen, silk, and metal works, &c.f The very numerous animal and vegetable substances derived from habita- tions are usually classed under the vague, but convenient term of organic matter, as the separation of the individual substances is impossible. The organic matter is usually nitrogenous, and Frankland has proposed to express its amount in terms of its nitrogen (organic nitrogen), but this view is not yet generally received on account of the difficulty of estimating the very small quantity of nitrogen. The nitrogenous organic matter undergoes gradual transformation, and forms nitrous and nitric acids and ammonia. The exact steps of this process are perhaps complicated. On keeping the water the nitrites disappear, and in some cases the nitrates also graduaUy diminish, per- haps from the action of bacteria. A. Miiller} found the residue of a well water gave with soda hydrate a herring-like odour, which seemed like truuetln - ^ Many of the organic matters in water are not actually dissolved, but are so finely suspended that they pass through filtering paper. There is no doubt that among this suspended organic matter many small plants and animals are always included. It is probably owing to the variation in the quantity of suspended organic matter (living and dead) that water from the same source sometimes gives different results on analysis, even though the water be taken at the same time. During its flow in open conduits, however, a species of purification goes on, by means of subsidence, the action of water-plants, and to some moderate extent by oxidation. On the whole, these processes appear in India to render river water, in spite of all the contaminations it receives, * For a good example of the influence of a tidal river on neighbouring wells, see my « Lectures %SKlSo! and the best mode of dealing with then,, the six Reports of the Rivers Pollution Commissioners must be referred to. £ Roth and Lex, Militiir-Gesundhcitsptl. p. 16.