TRANSACTIONS 
OF THE 
Cropdon Microscopical and Datural 
History Club. 
ee 
I. — On THE NatuRAL History oF HarpD WATER, AND ON 
ITS SOFTENING BY CLARK’S PROCESS. 
By ALFRED CARPENTER, Esq., M.D., President. 
[Read October 16th, 1878.] 
Dr. CARPENTER first produced three samples of pure rain 
water, also some water as supplied from the Board’s well in the 
town, and he poured three portions of each into test bottles. He 
explained that the rain which descended on to the chalk hills 
round Croydon, which hills were the source from which the 
Croydon water supply was derived, necessarily passed through 
the chalk, and in so doing dissolved certain of its ingredients 
which had an attraction for water. There were very few 
things in nature that water would not dissolve, but it had its 
preferences, and some of the things it preferred most were to 
be found in the water which we drank. Dr. Carpenter then 
poured into one phial of rain water some nitrate of silver ; 
into a second some oxalate of ammonia; and into the third 
some chloride of barium. None of these re-agents or tests 
appeared to have any effect in the rain water, but on pouring 
them, in the same order, into the phials containing the 
Board’s water it was found that, in the one containing nitrate 
of silver, the presence of chlorides was detected in the water ; 
in that containing oxalate of ammonia the presence of lime 
was indicated; and in the sample to which the chloride of 
barium had been added it was shown that the sulphates were 
present. He further explained that the tests also showed the 
presence of carbonates. When the rain water descended on 
to the hills and then passed deep into the ground, it absorbed 
carbonate of lime out of the chalk. ‘Two grains only of car- 
bonate of lime were taken up by each gallon of water, but as 
the rain water descended it carried with it carbonic acid, which 
was always present in the air, and this carbonic acid enabled 
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