Drinking-water and ice supplies and their relations to health and disease / by T. Mitchell Prudden.

  • Prudden, T. Mitchell (Theophil Mitchell), 1849-1924.
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: Drinking-water and ice supplies and their relations to health and disease / by T. Mitchell Prudden. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

    144/168
    old Ice age faded, is but a poor an d halting comparison. We cannot follow the student of these lowly forms of life, which have become entangled among the ice crystals, as he calls them back from their torpor, separates them one by one, and patiently studies their life history. It is not enough to melt the ice and look at the re- sulting water through the microscope. But he plants the melted ice in good bacterial food, and studies the forms which grow, and finds out how numerous they are. A great deal of careful experiment has shown that water in freezing largely expels its coarser visible contaminations, and also that a large proportion of the invisible bacteria which it contains may be destroyed, even as many as ninety per cent. But still large numbers may remain alive, for many species are quite invul- nerable to the action of cold. It has been found that in ice formed from water containing many bacteria, such as water with sewage contaminations, the snow-ice almost invariably contains many more living bacteria than the more solid, transparent part ; so that the snow-