Industrial uses of water / by H. de La Coux, tr. from the French and revised by Arthur Morris ; with 135 illustrations.

  • La Coux, H. de (Henri)
Date:
1903
Catalogue details

Licence: In copyright

Credit: Industrial uses of water / by H. de La Coux, tr. from the French and revised by Arthur Morris ; with 135 illustrations. Source: Wellcome Collection.

    26/406 page 12
    The farther water travels from ils source towards the sea, the more does it become charged with salts of potassium and sodium, and more especially with chloride of lime. Spring vvaters contain large quantities of carbonic acid, and little o.xygen ; streams, on the other hand, are more highly aerated. If spring water is clear, not so river water, which collects the rain which in its flow carries along organic and silicious matter, such as clay, sand and earth. This matter remains in suspension in the water, and the mud- diness thus occasioned is generally more noticeable when the waters are in flood. In the Hydrometric Service of the basin of the Seine the degree of transparency of the water is determined as follows :— A white object, one decimétré square, is immersed to a depth of 30 centimètres in the water to be tested. If the object is distinctly visible the water is clear. If the object is indistinctly visible the water is considered doubtful. If the object is invisible the water is turbid. The gentler the slope—in other words, the slower the current— the more readily is the suspended matter in the water deposited. This deposit constitutes the slime, and the organic matter of which it is composed combines with silicious substances, with salts of calcium, with aluminium and with oxide of iron. The sériés of tests of Seine water made by M. Hervé Mangon at Port-à-l’Anglais, and extending over a period of three years, gave an average of 39'66o grammes of slime per cubic métré ; the maximum weight of slime per cubic métré stood at 626'I2 grammes,, and the minimum at r350 grammes. Analysis of the slime yielded the following proportions of minerai matter :— Per cent. Carbonate of lime 9-84 to ag'ôS Peroxide of iron and of aluminium 3'88 to lô'sz Water described as clear, following the practice of the Hydro- metric Service, must contain less than 10 grammes of slime per cubic métré. The proportion of slime présent in water varies considerably in different rivers, thus the Durance at Merundol contains an average of i ’454 grammes of slime per cubic métré, while the Var at La Gaude contains 3‘577 grammes. Seeing that the nature and amount of the suspended matter in- the water is so variable, it stands to reason that the composition» of the slime dilifers as widely.
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