Water-analysis : a practical treatise on the examination of potable water / by J. Alfred Wanklyn and Ernest Theophron Chapman.

  • Wanklyn, J. Alfred (James Alfred), 1834-1906.
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: Water-analysis : a practical treatise on the examination of potable water / by J. Alfred Wanklyn and Ernest Theophron Chapman. Source: Wellcome Collection.

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    help of a lamp, and kept boiling until the water in the platinum dish has evaporated away. In the course of an hour this will have taken place, and the residue in the platinum dish will soon dry. The dish is allowed to remain in the bath for about ten minutes after it appears to be dry (in order to ensure com- plete dryness), and then re- moved from the bath, wiped externally, allowed to cool for a few minutes in contact with the iron or porcelain, and weighed. If the weight of the empty dish be subtracted, the weight of the water-residue will be obtained. In this way we obtain the weight of the solid residue left by 70 c. c. of water. Now, one gallon of water weighs 70,000 grains, and 70 c. c. of water weighs 70,000 milligrammes; so that 70 c. c. of water is a sort of miniature gallon, wherein the milligramme corresponds to the grain. If we know the number of milligrammes of residue which 70 c. c. of water leave, we know the number of grains of solids in a gallon of the water. To make everything clear we give an example:— Quantity of the sample of water taken, equals 70 c. c. Weight of dish and residue . 55'500 grammes. Weight of empty dish . . 5 5-421 „ •079 Therefore the total solids in tliis sample of water amounted to 79 grains per gallon