Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 Excerpt: ...dissolving 02 g. of lacmoid in 100 c.c. of dilute alcohol (10 per cent.). A few drops added to 10 c.c. of the sample of water, contained in a sample tube, at once reveals the presence of the smallest trace of acid. Moorland waters which give a neutral reaction with this indicator do not dissolve lead to any appreciable extent. Conversely, whenever a peaty water gives an acid reaction with lacmoid it will also be found to possess the power of acting as a solvent for lead. If a water is found to give an acid reaction with lacmoid, the amount of the acidity is determined by titrating a definite quantity of the water with a decinormal solution of sodium carbonate (5-3 g. Na2CO3 per litre). Phenolphthalein (0-5 g. in 100 c.c. of 50 per cent. alcohol) is used as indicator, as although open to some objections, it is found that comparable results are obtained. The results are expressed as acidity, in terms of c.c. of A/10 Na2CO3 required to neutralise 100 c.c. of the water. 1 Die Wasserversorgung von Zurich, 1885, p. 104. 'J Loc. cit., p. 61. 3 Thirteenth Annual Report of the Local Government Board, 1900-01. Supplement in continuation of the Report of the Medical Officer for 1900-01, "On Le.id-poisoning and Water Supplies," p. 67. Hardness. English degrees of hardness (Clark's scale) are equivalent to grains of calcium carbonate per imperial gallon of 70,000 grains; multiplied by 1-43 they give parts per 100,000. In Germany, degrees of hardness indicate the number of parts by weight of calcium oxide in 100,000 parts by weight of water, any magnesium compounds present being taken into account as equivalent quantities of calcium oxide. Thus, if a water is said to have a hardness of 10 it is concluded that in 100,000 parts by weight it contains calcium and m...
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