me, and, after
allowing it to settle again, poured off as much of the clear ley as
possible.

The lime and alkali were mixed together under the form of a very thick
milky liquor or fluid paste; because they are thus kept in perpetual
contact and equal mixture until they have acted sufficiently upon one
another: whereas in the common way of using a larger quantity of water,
the lime lies for the most part at bottom, and, tho' stirred up ever so
often, cannot exert its influence so fully upon the alkali, which is
uniformly diffused thro' every part of the liquor.

The above ley was found upon trial to be saturated by acids without the
least effervescence or diminution of weight.

It was now proper to examine whether the alkali suffered any loss in
becoming caustic, which I proposed to attempt by ascertaining the
strength of the ley, or the quantity of salt which a given portion of it
contained; from which by computation some imperfect knowledge might be
obtained of the quantity of caustic produced from the eighteen ounces of
mild salt.

I therefore evaporated some of my ley, but soon perceived that no
certain judgment could be formed of its strength in this way, because it
always absorbed a considerable quantity of air during the evaporation,
and the dried salt made a pretty brisk effervescence with acids, so that
the ley appeared stronger than it really was; and yet, upon proceeding
in the estimate from this rude and unfair trial, it appeared that the
salt had lost above a sixth in becoming caustic, and the quantity of
acid saturated by two drams of it was to the quantity of acid saturated
by two drams of salt of tartar, nearly as six to five.

These experiments are therefore agreeable to that part of the second
proposition which relates to the caustic alkali.

Upon farther examining what changes the alkali had undergone, I found
that the ley gave only an exceeding faint milky hue to lime-water;
because the caustic alkali wants that air by which salt of tartar
precipitates the lime. When a few ounces of it were exposed in an open
shallow vessel for four and twenty hours, it imbibed a small quantity of
air, and made a slight effervescence with acids. After a fortnight's
exposure in the same manner, it became entirely mild, effervesced as
violently with acids, and had the same effect upon lime-water as a
solution of an ordinary alkali. It likeways agrees with lime-water in
this respect, that it may be kept in close