London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
Kensington 1887
[Report of the Medical Officer of Health for Kensington]
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244
consequence of the vegetable life which then abounds in such water.
On this account, therefore, the amount of total combined nitrogen
found in the water during the winter months can alone be regarded as
bearing any relationship to the amount of nitrogenous matters which
these waters have received. During the past two years there has been
an appreciable increase in the proportion of this combined nitrogen,
due, probably, to the summer droughts and consequent freedom from
floods: the nitrogenous organic matters thus accumulate on the land
and there undergo nitrification instead of being rapidly carried away
into the rivers; the nitric nitrogen thus formed during the dry summer
months then finds its way into the rivers during the more rainy
months of the winter.
The following table exhibits the proportional amounts of organic elements
(organic carbon and organic nitrogen) in the waters of the Companies
which supply Kensington; the Kent Company's water being taken as
the standard of puritv for comnarison:—
| Name of Company. | Maximum. | Minimum, | Average. |
|---|---|---|---|
| Kent | 0.9 | 0.4 | 0.6 |
| Chelsea | 5.2 | 1.4 | 2.8 |
| Grand Junction | 6.1 | 0.9 | 2.6 |
| West Middlesex | 5.5 | 2.1 | 2.9 |
The average proportion of chlorine in the river waters has, during the past
three years been slightly in excess of that usually present, the increase
being doubtless attributable to the small rainfall.
The term "hardness" is used to denote the proportion of carbonate of
lime, or its equivalent of other soap-destroying substances, present in
100,000 parts of water. The mean hardness of the Thames water was
19.3, that of the Colne Valley Company, after a softening process,
being 5.7. The hardness of the river waters is not so excessive as
to influence their fitness for drinking, but it is sufficient to materially
diminish their value for washing, steam, and industrial purposes
generally. This hardness is almost entirely due to the presence of
bi-carbonate of lime in solution: this bi-carbonate of lime, however
can be readily removed by treating the water with lime, and is
successfully done by the Colne Valley Company, with the result that
the hardness of that Company's water is reduced, before delivery, to
less than one-fifth of its original amount. The hardness of the river
supplies is similarly reducible. This mode of softening is by far the
most economical, for it entails only about one-eightieth of the expense
which devolves upon the private consumer in the shape of additional
soap required for washing purposes.