2 Dr. Carpenter 
the water to take up a much larger quantity of lime, as a 
bicarbonate, which was much more soluble than the carbonate. 
The ordinary constituents of chalk water in this district were 
22 grains of bi-carbonate of lime to a gallon. Sometimes this 
quantity was exceeded—z8 grains were not unusual in some 
places, and in others even a greater proportion. The water 
having thus absorbed this carbonate and bi-carbonate, also 
became charged with a certain amount of sulphate of lime, 
which was more soluble even than bi-carbonate of lime. Cold 
water would take up 150 grains of it per gallon. In the chalk 
there was also salt in small quantities, and hence the presence 
of chlorides in the water. In the water supplied to this town 
there was always found, when it was pure, two grains of 
common salt (which was a chloride of sodium) to the gallon, 
but if that quantity was exceeded by say eight, ten, or twelve 
grains to the gallon, it was quite certain that the water had 
been rendered impure by the admixture of sewage. Bi-car- 
bonate of lime existed in water while it was cold, but if the 
water was boiled much of the carbonic acid was driven off 
from the lime, and passed again into the air from whence it 
came, whilst the lime was set free as a carbonate and was 
deposited. It was from this effect of boiling chalk water that 
a quantity of carbonate of lime was found in our kettles, 
boilers, hot water pipes, &c. Dr. Carpenter exhibited speci- 
mens of pipes, the apertures of which had been almost 
completely closed by the lime deposits. He then explained 
at some length how carbonate of lime forms a large part of 
the solid strata of which the globe is made up, and exhibited 
on the table a large number of specimens of minerals of which 
lime formed part. Sometimes the lime is obtained in trans- 
parent crystals, but it is generally mixed with other earths, 
with metals, &c., and in these various states it is known by 
the names of chalk, limestone, stalactites, marble, calcite, 
aragonite, &c. Dr. Carpenter then went on to say that the 
presence of lime in our water enabled us to have it in a pure 
state for drinking purposes. Water, in all parts of the world 
seemed to have a preference for lime, and wherever it trickled 
through ground containing lime, it dissolved the lime in con- 
siderable quantities. This was one of the means adopted by 
Providence to provide us with pure water. If we had water 
too pure, it would more easily absorb metals of a poisonous 
nature, but the presence of lime in water prevented the easy 
admission of much poisonous material. Our housekeepers 
found that boiling water was a much better solvent than cold 
water, because, in the process of boiling, about 20 grains of 
lime were thrown out, leaving only two grains, more or less, 
in the liquid. It had been proposed to separate lime from 
