ilver
always almost at its boiling point. Nothing remarkable took place during
the first day: The Mercury, though not boiling, was continually
evaporating, and covered the interior surface of the vessels with small
drops, at first very minute, which gradually augmenting to a sufficient
size, fell back into the mass at the bottom of the vessel. On the second
day, small red particles began to appear on the surface of the mercury,
which, during the four or five following days, gradually increased in
size and number; after which they ceased to increase in either respect.
At the end of twelve days, seeing that the calcination of the mercury
did not at all increase, I extinguished the fire, and allowed the
vessels to cool. The bulk of air in the body and neck of the matrass,
and in the bell-glass, reduced to a medium of 28 inches of the
barometer and 10 deg. (54.5 deg.) of the thermometer, at the commencement
of the experiment was about 50 cubical inches. At the end of the
experiment the remaining air, reduced to the same medium pressure and
temperature, was only between 42 and 43 cubical inches; consequently it
had lost about 1/6 of its bulk. Afterwards, having collected all the
red particles, formed during the experiment, from the running mercury
in which they floated, I found these to amount to 45 grains.

I was obliged to repeat this experiment several times, as it is
difficult in one experiment both to preserve the whole air upon which we
operate, and to collect the whole of the red particles, or calx of
mercury, which is formed during the calcination. It will often happen in
the sequel, that I shall, in this manner, give in one detail the results
of two or three experiments of the same nature.

The air which remained after the calcination of the mercury in this
experiment, and which was reduced to 5/6 of its former bulk, was no
longer fit either for respiration or for combustion; animals being
introduced into it were suffocated in a few seconds, and when a taper
was plunged into it, it was extinguished as if it had been immersed into
water.

In the next place, I took the 45 grains of red matter formed during this
experiment, which I put into a small glass retort, having a proper
apparatus for receiving such liquid, or gasseous product, as might be
extracted: Having applied a fire to the retort in a furnace, I observed
that, in proportion as the red matter became heated, the intensity of
its colour augmented. When the