Water supplies : their purification, filtration, and sterilisation; a handbook for the use of local and municipal authorities / by Samuel Rideal and Eric K. Rideal.

  • Rideal, Samuel, 1863-1929.
Date:
1914
Catalogue details

Licence: In copyright

Credit: Water supplies : their purification, filtration, and sterilisation; a handbook for the use of local and municipal authorities / by Samuel Rideal and Eric K. Rideal. Source: Wellcome Collection.

    32/378 (page 16)
    and the saline matters may add a piquant taste, so that the liquid is often drunk without suspicion, and in recorded cases has even been preferred to a purer supply, although chemical and bacterial analysis would condemn it at once, and im- paired health and well-known diseases are conclusively traced to its use in the raw state for drinking. A scheme of the order in which many of these products are formed from proteids is as follows :— They first give odorous bodies, like indol, skatol, H2S and thio-compounds with albumoses and peptones. The 'latter yield polypeptides and afterwards ptomaines and purin bases, which break up into a number of simpler bodies, with amino- and fatty acids, and phenol derivatives. Finally carbonic acid and ammonia are produced ; the latter should become oxidised to nitrites and then to nitrates, which are innocuous but a sign of former organic nitrogenous matter: the late Sir E. Frankland, in fact, tabulated them as “previous sewage contamination.” Nitrites are an unfavour- able indication, either that oxidation is incomplete, or that it has been reversed by some reduction of nitrates which may indicate anaerobic bacteria (some of which are among the most dangerous), and in many cases has to be explained. Many of the organic products of decomposition have been isolated, but the work is at present scarcely begun. That on the polypeptides has been mainly carried out by E. Fischer.* Of the ptomaines that have been isolated may be mentioned neuridin and cadaverin, while among the amino-acids are glycocoll, leucin and tyrosin and many others. These yield amines and ammonia as well as some free nitrogen. The following amines have been separated, methylamines (a large quantity in herring brine), ethylamine, ethylene-diamine, indol, and others: all are injurious and may pass into drinking water as a consequence of putrefactive contamination. Plant tissues break down in a similar manner as regards their proteid substances, but on account of their cellulosic and lignin (woody) constituents they can give a larger quantity of the intermediate brown amorphous products containing some * Ber.-, 1908, et seq.