The hygiene of air and water : being a popular account of the effects of the impurities of air and water, their detection, and the modes of remedying them / by William Proctor.

  • Proctor, William.
Date:
1872
Catalogue details

Licence: Public Domain Mark

Credit: The hygiene of air and water : being a popular account of the effects of the impurities of air and water, their detection, and the modes of remedying them / by William Proctor. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    water dissolves soap, with scarcely any change. Whilst water holding salts of lime, magnesia, or iron, in solu- tion, is called hard, and decomposes or curdles soap. The so-called hardness is due chiefly to the carbonates, sulphates, and chlorides of calcium (lime), and mag- nesium. The carbonates are held in solution by the gas carbonic acid, and when the water is boiled, this gas, by which the solution is effected, being driven off, they are precipitated. The production of fur in kettles and boilers, &c., is the result of this action. By the removal of the carbonates in this manner, the remaining water is Tendered softer, but it may, according to the original com- position, still retain an amount of (permanent) hardness due to the matter (sulphates and chlorides) not precipitated. It is on the same principle that water, the hardness of which is due to carbonate of lime, is softened by the addition of lime. The former substance is remov^ by precipitation, carrying down with it suspended matters, as well as the more organised organic matter.,,if it^present, and leaving behind that portion which, in a sanitary point of view, is of less consequence. The action of soda, in softening water for washing, tea-making, &c., is of a similar kind. Characters of Good Water.—We are now in a position to consider the qualities which good potable water should possess. Dr. Parkes gives the following as the essential characters in relation to the dissolved con- stituents. Organic matter should not exceed one-and-a- half grain per gallon ; carbonate of lime, 16 grains ; sulphate of lime, 3 grains ; carbonate and sulphate of