Service chemistry : being a short manual of chemistry and metallurgy and their application in the naval and military services / by Vivian Byam Lewes and J.S.S. Brame.

  • Vivian Byam Lewes
Date:
1913
Catalogue details

Licence: In copyright

Credit: Service chemistry : being a short manual of chemistry and metallurgy and their application in the naval and military services / by Vivian Byam Lewes and J.S.S. Brame. Source: Wellcome Collection.

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    been in this way used nj), ]io soap will be available for cleaning purposes. Advantage is taken of this action to determine the relative hardness of waters, by seeing how much of a soap solution of known strength a given water can convei't into these insoluble compounds. The supply of water, for instance, at Greenwich is derived from deep wells in the chalk, and on analysis is found to contain— Temporary hardness. Calcium carbonate . . 16’30 grains per gallon. ( Calcium sulphate . . 5‘30 Permanent hardness. Magnesium sulphate 0'93 ,, Magnesium nitrate .. 1-20 Sodium chloride 2-64 Sodium nitrate 1-21 Silica, alumina, etc. .. 0-97 28-62 The hardness of a water is expressed in degrees, one degree of hardjiess representing the soap-destro^dng power imparted to one gallon of it by the presence in solution of one grain of chalk ; so that when a water is said to have ten degrees of hardness, it means that it contains ten grains of chalk per gallon of water, or its equivalent in other lime and magnesium salts. The Green- wich water supply is said to have twenty-four degrees of hardness, lG‘5of these being due to temporary and 7‘5 to permanent hardness. Now one degree of hardness will use up and waste ten grains of soap per gallon of water used, and with large quantities of hard water this rapidly mounts up to a veiy high figure. For instance— Pounds of soap wasted per 100 gallons of water. 3*66 7-31 11-12 14-75 18-41 Salts in Solution in Spring Water.—Besides calcium carbonate and sulphate, we find in si)ring water the sulphates, carbonates, chlorides and nitrates of magnesium, potassium, sodium, manganese, and iron, and also small quantities of organic matter and occasionally silicates. Degree of hardness of water used. 5° 10° 15° 20° 25°
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