An introduction to the bacteriological examination of water / by W.H. Horrocks.
- Horrocks, W. H. (William Heaton), Sir, 1859-
- Date:
- 1901
Licence: In copyright
Credit: An introduction to the bacteriological examination of water / by W.H. Horrocks. Source: Wellcome Collection.
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![relation between the number of organisms and the chemical composition of the water. Bolton’s work pointed in the same direction; he distinctly said that the chemical composition of a water had no relation to the number of micro-organisms. Tiemann and Gartner believe that, in relation to nutritive material, bacteria may be ax’ranged in two groups. The first group includes the water bacteria, which have very slight dependence on the nutritive material present, and under favour- able conditions multiply rapidly. The second group embraces those organisms which are greatly dependent on the nutritive material present, and are derived from the earth and living beings. With regard to the organic matter the difficulties are very great; we are not able to determine exactly which of the constituents form suitable food for bacteria, indeed Duclaux has said that the quality of the organic matter is far more important than the quantity. Using the oxygen derived from potassium permanganate as a test, Fischer found in one case 7T parts per 100,000 of oxygen absorbed with 800 bacteria pi-esent, and in another case only 0*5 part per 100,000 of oxygen absorbed with 360,000 bacteria present. Tiemann and Gartner investigated the effect of inorganic substances, especially lime salts and total solids on the bacterial contents; the results obtained were as follows : Number of wells. 1 30 1-t 1 Hardness. Organisms ] 0-10 536 10-20 1,695 20-30 1,910 30-10 720 Total solUs. 0-50 60-100 100-150 200-500 Orgaui.sms per e.c. 81 261 2.50 16 These i-esults show that often a high bacterial count is associated with high total solids, but with an excess of solids the organisms may diminish again. A review of all the experiments appears to justify the](https://iiif.wellcomecollection.org/image/b28116525_0059.jp2/full/800%2C/0/default.jpg)
