The Rivers Pollution Commission value the quality of water by the previous sewage or animal contamination, as they term it. This expression is obtained by taking, as a standard of comparison, the amount of total combined nitrogen (which is assumed as 10 parts), in solution, in 100,000 parts of average London sewage. The parts of nitrogen obtained, in the form of nitrates, nitrites, and ammonia, less .032 part of 100,000 for that portion in rain, is that nitrogen derived from animal matter. Animal matters dissolved in water, such as those contained in sewage, the contents of privies and cess-pools, or farm-yard manure, undergo oxidation in lakes, rivers and streams very slowly, but, in the pores of an open soil, very rapidly. When this oxidation is complete, they are resolved into mineral compounds; their carbon is converted into carbonic acid; and their hydrogen into water; but their nitrogen is transformed partly into ammonia and chiefly into nitrous and nitric acids. The following table is a compilation of their analyses:
POTABLE WATERS, FROM ANALYSES BY RIVERS POLLUTION COMMISSION, (1874,) (PARTS OF 100,000 PARTS.)
================================================+=======+=========+======== |Organic| Organic |Previous |Carbon.|Nitrogen.| Sewage. ------------------------------------------------+-------+---------+-------- | parts | parts | Rain-water, collected in leaden gauges | .070 | .015 | 42 “ “ “ from roofs, etc., for | .257 | .080 | 12031 domestic use | | | Dew or hoar frost collected on leaden gauges | .264 | .076 | 1536 Sea-water | .278 | .165 | 103 Upland surface, from non-calcareous strata | .278 | .033 | 0 “ “ from calcareous strata | .346 | .037 | 33 Land drainage water, from sewage farms | .082 | .191 | 10443 Deep well waters, in the chalk below London clay| .093 | .028 | 797 Spring waters, from the chalk | .044 | .010 | 3511 Bristol, from springs and deep wells | .172 | .024 | 16620 Edinburgh, from springs and streams-- | .145 | .026 | 2020 water filtered | | | Glasgow, from Loch Katrine | .204 | .017 | 0 Liverpool, Green Lane well | .020 | .020 | 3840 “ Rivington River, gravity supply, | .243 | .031 | 0 unfiltered | | | “ “ “ gravity supply, | .210 | .029 | 0 filtered | | | Birmingham, from Bourne River, normal | .211 | .039 | 2480 “ “ “ “ in flood | .640 | .059 | 3890 “ “ “ “ filtered | .460 | .045 | 2720 “ from Aston well | .034 | .006 | 1440 “ mixed waters--river and well | .040 | .010 | 1380 London, Thames water from Hampton | .246 | .033 | 3270 Grand Junction Works | | | “ “ “ after subsidence “ “ “ | .262 | .042 | 3270 “ “ “ after filtration “ “ “ | .231 | .032 | 3140 Jacob’s Shallow Well, at Sheffield | 1.200 | .126 | 590 ------------------------------------------------+-------+---------+--------