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the whole, satisfactory set of results. These waters contain
always a certain amount of solid ingredient, the actual quantity
of which depends clearly on the weather; for it is least in hot
and dry weather, and most in rainy and wintry weather Thus,
in writing out the results of a series of analyses by various authorities
and by ourselves during the last ten years, the lowest
quantity has been in September. Thus, in September 1864, the
total solid contents of the Grand Junction water were so low as
14.76 grains per gallon; in June 1859, the Chelsea contained
only 14.92; and during the summer generally—as of 1865, for
instance—16 or 17 grains per gallon is a fair average. During
the winter months it averages from 19 to 2.2; and, in January,
1861, it reached 23. Last October it was 17: in November it
jumped to 20, and maintained that average during the winter.
So much for total quantity, which is ascertained by evaporating
a given measure of water, and drying the residue at 230°. Of this
about nineteen-twentieths consist of earthy salts, which make the
water hard; and we may say in round numbers, that three-fourths
of these earthy salts consist of chalk, which is deposited in the
inside of our kettles and boilers, and furs them up and makes them
liable to crack. When the water is boiled the chalk first turns
the water milky, and then goes to the bottom. About 600 gallons
of water would throw down a pound of fur. This chalky matter
spoils a good deal of soap, and requires about 2½ its weight of
soda to soften the water; but it is quite innocent as a drink; some
people think it pleasant, and some beneficial.
Besides the earthy matter, the water contains about one grain
in the summer, and about a grain and a half per gallon in the
winter of matter which can be burned off at a red heat, and in
which more refined chemical processes can detect usually about
a third of a grain of real organic matter. It is this in which
organic poisons lurk if present at all, and which is found in immense
quantities in water contaminated with sewage, and especially
in the water of the pumps near Mount-street—(See Quarterly
Report, No. xxvii., p. 10.)
It is highly satisfactory to know that the quantity of organic
matter in the Grand Junction and Chelsea waters is on the whole
decreasing; and that it is least in the hot season, when sewage
contamination might cause cholera, or at least diarrhoea. Still,
every family should have a good filter, and drink no water unboiled
that is not perfectly bright.
Nature of Epidemics—Threatening of Cholera.
The nature of epidemics is well seen in the history of the
measles so far as they have affected the Hanover and Mayfair
Sub-Districts of late. During the quarter ended April 1st, 1865,
there was only one case reported amongst the out-door sick poor.
Then the disease was absent till the week ended 22nd April, in
which there were 2 cases; in the following weeks in succession
the numbers were 2, 4, 7, 5, 28, 20, 9, 4, 12, 8, 4, 5, 11, 2, 4, 2, 2,
0,1,0. After this, one case appeared in November, 3 in December,
during which months scarlatina prevailed; but there was no case