On Water and Air . 
59 
1880.] 
precipitation of bicarbonate of lime, or to the precipitation of 
single carbonate of lime? Which? Somebody lisps out 
“ The single carbonate.” I wish he had courage enough. to 
say it out. It is the single carbonate 5 and here is the point 
which I want you to predict. Suppose I continue to pour a 
sufficient quantity of carbonic acid into the water: suppose 
I continue to supply the carbonic acid : what will occur ? 
The single carbonate, having plenty of carbonic acid to take 
up, will be converted into the bicarbonate, and after having 
first of all precipitated the single carbonate, we shah convert 
it into the bicarbonate and re-dissolve it. And that is what I 
am going to try whether we can do. Here is our liquid, and 
here it is being rendered milky— very milky indeed— by 
means of the carbonic acid gas. And now, if you will give 
me your patience for a time, I am strongly inclined to think 
that, by the continued addition of the carbonic acid, we shall 
convert the single carbonate into the bicarbonate, and that 
that milky liquid will be rendered perfectly transparent by 
the solution of the single carbonate. Now, this is one of the 
things which men of science, and which boys learning 
science, ought to be able to foresee. If our principle be tr ue, 
then, by the addition of carbonic acid to the milky liquid, 
we shall convert the carbonate into bicaibonate. [The 
addition of carbonic acid was continued until the milky- 
iooking liquid became clear.] This is now bicarbonate.. If 
I pour into this liquid some lime-water, I shall rob the bicar- 
bonate of half its carbonic acid, and convert it into the single 
carbonate. [The experiment indicated was performed.] 
Here you see what occurs. You have the single carbonate 
in this insoluble form produced thus before you. Now, it is 
not for the purpose of amusing you that I bring this before 
you. It is for the purpose of bringing before your minds 
the manner of the reasoning of scientific men— the striftness 
of their logic — the incessant appeal from reason to fadts by 
which they verify what they conceive. 
I will now perform a very homely experiment, but still a 
very useful one. I want to give you some examples of the 
quality of this Canterbury water. Here are two basins in 
which I intend to produce a lather if I can. We will place 
in one of those basins some of the soft Canteibury water, 
and we will place in the other basin the ordinary tap watei 
of the Royal Institution, and I will wash my hands with 
your permission in both basins, and then we shall see where 
the best lather is produced. What you will observe is that, 
with a very small amount of soap, I shall be able to produce 
a very good lather ip the soft Canterbury water ; but I 
