Licence: Public Domain Mark
Credit: On water supply / by Stevenson Macadam. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![grain in the imperial gallon, and there is practically no dif- ference in the amount furnished hy each water. This organic matter is entirely non-putresceut. Where the peaty — is much greater in quantity, as in some of the compensation reservoirs on the Pentlands. the organic matter may be a nmch as IJ grains to 2i grains in the '-P«''l.S^°;,^f:;^ the water of Loganlea reservoir has one gram of organio matter i,i the gallon; whilst the highest proportion pi.sei in any feeder of St Mary's, or any portion of the loch, is ^TO, or four-fifths of a grain, which is the quantity found in the Little Yarrow. j f„ , r In waters which are contaminated by the products of animal matters derivable from sewage or from highly manured fields, the amount of organic matter ranges from 1 to 10 or more grains in the imperial gallon. The gases dfssolved in waters form one of the best guides as to the quality of the waters. These gases are mamly carbo- nic acid oxygen and nitrogen. The proportion of carbo- nic ac d aries'according to hardness, when such is derivable from carbonates; whilst the relative amounts o oxygen and nitrogen should be very nearly as 1 of oxygen to 2 of mtrogem When the water is of a wholesome nature, and the organic ma er is not putrescent, then such is the ratio of tnese Tses ■ but where there is putrescence, the oxygen decreases fo ] io 3, or less, which is indicative of positively unwhole- ome properties being present in the water. ^-^J^^^^^^^' Hhe course of the inquiry into the condition of the Water of Leith, I had occasion to make many testings which led to Aes re ults, and the subsequent analyses of many hundreds 0 waters received from all quarters has confirmed these ..ncUisions. The gases dissolved in the waters of the Edin- burii or Pltland! South E.k, and St Mary's Loch districts are as follows, taking the average results of many experi- ments made on each set of waters :— F.linbnr-li South Esk Bt Mary's Loch Spring Wrter. Kiver Water. and Feeders. Carbonic acid, . 10 ^5 3q| Oxygen, • • g, 65 65J Nitrogen, . ■](https://iiif.wellcomecollection.org/image/b21957381_0008.jp2/full/800%2C/0/default.jpg)
