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

  • Wanklyn, J. Alfred (James Alfred), 1834-1906.
Date:
1896
Catalogue details

Licence: Public Domain Mark

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

    30/214 (page 26)
    After the water-analyst has obtained the solid residue and weighed it, he will do well in making a slight examination of it. If a few drops of hydrochloric acid be poured on it, effervescence will generally occur. This shows the presence of carbonates, which almost invariably consist of carbonate of lime. This qualitative examination for carbonates con- sumes hardly any time, and should hardly ever be omitted, inasmuch as a knowledge whether or not there are car- bonates in the water is useful in various ways. The water-residue in the platinum dish may likewise be gently ignited, and the observation recorded, whether it blackens during the ignition. The weight of the residue after ignition may likewise be taken. Formerly, before the modern development of water-analysis, the loss on ignition was regarded as a very important datum, and as indicating the quantity of organic matter in the water; but now we know that the loss on ignition is valueless for any such purpose. The different varieties of water which serve for the pur- poses of daily life fall under two categories (1) There are those natural waters which contain very little mineral matter, and (as a consequence of their neces- sarily small charge of carbonate of lime, or other mineral base) are only to a small degree charged with carbonic acid. The specific gravity of the waters coming under this cate- gory is low, ranging from 1000.05 to 1000.15. Historically these waters are, generally speaking (but not invariably), natural rain-waters, which have never dissolved more than a very minute proportion of mineral matter. They are the minerally-pure waters. (2) Under the second category range themselves the