Water analysis for sanitary purposes, with hints for the interpretation of results / by E 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 the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    measured, and an aliquot part taken and diluted to 50 c.c. with pure water. The various amounts of ammonia in the distillates must be added together, and the total calculated into parts per 100,000 of the water taken. When the evolution of ammonia is long continued, it is owing to the decomposition of urea. In such cases collect the distillate in smaller quantities and Nesslerise only that which is rapidly evolved. The lingering ammonia, which comes off after this, is due to the decomposing urea, and may be neglected. The estimation of ammonia is undertaken chiefly because this compound is often derived from animal matters just beginning to decompose, and its presence therefore gives an indication of the recent, and probable present, existence of animal pollution. Unpolluted waters seldom contain much ammonia, the greatest amount being found in rain water, which, when collected in towns, sometimes contains as much as 210 part in 100,000 parts of water. Rain water collected in the country, however, contains on an average only '030 part per 100,000. This quantity, which is solely derived from the air, is soon absorbed by vegetation; hence upland surface waters show but '002 on the average, or '008 as the maximum. In river water the proportion rarely exceeds 01, and in good well water it is usually still less ; whilst in spring water it is either absent altogether or present in very minute proportions. On the other hand, sewage always contains a large quantity of ammonia (about 5 parts per 100,000 on the average, but varying from 2 parts to 10), and so in general do waters to which sewage gains access. The proportion of ammonia, however, in water polluted by sewage, varies between very wide limits. In shallow wells, for instance, it varies from 0 to as much as 2-75. Ammonia in the presence of oxygen and animal matters is rapidly converted, during the filtration of water through porous earth, into nitrates and nitrites ; and its