Water analysis for sanitary purposes : with hints for the interpretation of results / by E. Frankland.

  • Edward Frankland
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: Water analysis for sanitary purposes : with hints for the interpretation of results / by E. Frankland. 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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    brown until a precipitate is produced. The amount of am- monia in each cylinder is estimated by enmparisun with the colours produced by the test in other cylinders containing equal volumes of pure water to which known quantities of ammonic chloride have been added. The solution of ammonia must never be so concentrated as to produce a precipitate, otherwise the estimation is vitiated and must be commenced de novo with a more dilute solution. The operation is conducted as follows ;—A cylinder containing 50 c.c. of distillate is ])laced on a white tile, and 1 c.c. of Nessler solution is added. The contents of the cylinder are stirred up, and the liquid is allowed to stand five minutes. To imitate the tint then produced a clean cylinder is taken, and into it is measured, from a suitable burette, as much of the standard solution of dilute ammonic chloride as experience would suggest. The cylinder is then filled up to the 50 c.c. mark with water free from ammonia, and 1 c.c. of ^^essler solution added as before, and the trial cylinder placed on the white tile beside the one to be tested. The tints are best observed by placing the cylinders in a good light and looking down on the surfaces of the liquids at an angle of about 60 degrees. If the colours are the same in each cylinder, the amount of standard solution used indicates the amount of ammonia contained in the cylinder tested. If the colours are unequal, a second trial is carried out with more or less, as the case may require, of the standard solution of ammonia. The colour produced by more than 2 c.c. of the standard solution of ammonic chloride (see Appendix I, A, 2) is too intense for accurate comparison. It is therefore often advisable to leave the first cylinder of distillate (containing the greater part of the ammonia) until the second has been tested. If, then, the ammonia contained in the second amounts to 0’5 and upw'ards, the first will contain too mucli ammonia for accurate estimation. It must therefore be
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