Conservancy and
Sanitary Arrangements.
48
A SKETCH OF THE MEDICAL HISTORY OF THE NATIVE ARMY OF BOMBAY.
3. The conservancy and sanitary arrangements continue as satisfactory as can be ex--
pected considering local deficiences and drawbacks. Nothing
effectual has as yet beendone to secure for this fort and garrison
a larger and. better supply of potable water. A masonry filter
erected inthe Mamoo Banja Tank, which some years previously
(1871) had proved a failure, was re-opened and somewhat
modified as to the number and disposition of its filtering chambers and contents, and on
the same principle as that of a filter constructed at Haripur, in the Punjab, said to have been
favourably noticed in some of the published papers on Indian engineering. It seems to have
consisted of one large and deep filtering chamber communicating with the cistern or settling
reservoir by means of a masonry duct or tube with a syphon action. The filter here appears
to have, in addition, an extra chamber, wherein the denser impurities collect and are
precipitated before the water can reach the filtering chamber; the filtering medium utilised
in this latter, was composed of sand and gravel of various degrees of fineness, with a good layer
of charcoal placed about the middle of the filtering strata. Moreover, the finest description of
sand was at considerable cost procured from Mortakka, on the Nerbudda, and the filtering
trata packed so close as to ensure the slowest and most perfect percolation practicable. The
filtering beds were disposed, briefly, as follows:—
Upper layer, 6" finest dust sand procurable.
18" fine, sharp, quartz river-sand.
9" of "khair" charcoal.
10" of coarse sand.
4" of smaller gravel.
Lowest layer, 4" of coarse pebbles.
Each layer was separately rammed and consolidated so as to form, as it were, a solid
mass, and thus after a week's consolidation the various strata formed, as regards closeness
of grain, as perfect; a filtering medium as it seemed possible under the circumstances to effect.
On the morning of the 19th of July, when all was ready, the tank water was pumped into
the first filtering chamber, and the operation slowly continued, with a head of 15" carefully
worked up to, when, at 1 P. M. the next day (that is 31 hours after the work of pumping had
begun), a small thread of water appeared issuing from the cistern. The operation as a crucial
experiment was continued for 9 days—the filter each day being scoured out through the
outlet cocks. Both process and materials in this experiment have thus been carefully de--
scribed, as given by the engineer, in order to show that no pains apparently were spared to
ensure the success of the experiment; and this, taken in conjunction with several former
trials and. the slowness and thoroughness of the experiment proves, it would seem, conclusive-
-ly the impracticability of filtering this tank water for drinking purposes by means of an
artificial measonry filter of this kind, however elaborate. The following is the analysis of the
tank water after the experiment; the water was contained in glass-stoppered bottles, measured
about 1 gallon, and arrived at the laboratory 3rd August 1875:—
Grs. per Gallon.
Total solids dried at about 280° F
15.96
Loss on ignition (blackening intense)
1 . 6 0
Chlorine
2.80
Sulphuric acid
Nil.
Lime
3 . 1 3
Magnesia
1.10
Silica
2.80
Carbonic acid (combined)
6.75
* Hardness before boiling (total)
6°.30
...
After boiling, permanent
2°.80
Temporary
3°.5
Ammonia—
Parts per Million.
Indistillate from carbonate of soda, free
.02
Indistillate from permanganate of potash albumenoid
.48
Of nitrates and nitrites
1.80
Oxygen —
Grs. per Gallon.
Total required by the water at 140° F. in presence of acid
1330
After evaporation to about 1/10th, with chloride of aluminum and re-
dilution
"
For iron salts
"
Water-supply,