e candle, the putrefying substance, the lungs of the
animal, or the charcoal. That there is a precipitation of lime when
nitrous air is mixed with common air, I had not then observed, but I
have since found it to be the case.

That there was no precipitation of lime when brimstone was burned, I
observed, p. 45. might be owing to the fixed air and the lime uniting
with the vitriolic acid, and making a salt, which was soluble in water;
which salt I, indeed, discovered by the evaporation of the water.

I also observed, p. 46, 105. that diminished air being rather lighter
than common air is a circumstance in favour of the fixed, or the
heavier part of the common air, having been precipitated.

It was upon this idea, together with others similar to it, that I took
so much pains to mix fixed air with air diminished by respiration or
putrefaction, in order to make it fit for respiration again; and I
thought that I had, in general, succeeded to a considerable degree, p.
99, &c. I will add, also, what I did not mention before, that I once
endeavoured, but without effect, to preserve mice alive in the same
unchanged air, by supplying them with fixed air, when the air in which
they were confined began to be injured by their respiration. Without
effect, also, I confined for some months, a quantity of quick lime in a
given quantity of common air, thinking it might extract the fixed air
from it.

The experiments which I made with electricity were solely intended to
ascertain what has often been attempted, but, as far as I know, had
never been fully accomplished, viz. to change the blue colour of
liquors, tinged with vegetable juices, red.

For this purpose I made use of a glass tube, about one tenth of an inch
diameter in the inside, as in fig. 16. In one end of this I cemented a
piece of wire _b_, on which I put a brass ball. The lower part from _a_
was filled with water tinged blue, or rather purple, with the juice of
turnsole, or archil. This is easily done by an air-pump, the tube being
set in a vessel of the tinged water.

Things being thus prepared, I perceived that, after I had taken the
electric spark, between the wire _b_, and the liquor at _a_, about a
minute, the upper part of it began to look red, and in about two minutes
it was very manifestly so; and the red part, which was about a quarter
of an inch in length, did not readily mix with the rest of the liquor. I
observed also, that if the tube lay inclined while I