And though neither of
these Atramentous liquors will seem other than very Pale Ink, if you write
with a clean Pen dipt in them, yet that is common to them with some sorts
of Ink that prove very good when Dry, as I have also found, that when I
made these carefully, what I wrote with either of them, especially with the
Former, would when throughly Dry grow Black enough not to appear bad Ink.
This Experiment of taking away and restoring Blackness from and to the
liquors, we have likewise tryed in Common Ink; but there it succeeds not so
well, and but very slowly, by reason that the Gum wont to be employed in
the making it, does by its Tenacity oppose the operations of the above
mention'd Saline liquors. But to consider Gum no more, what some kind of
Praecipitation may have to do in the producing and destroying of Inks
without it, I have elsewhere given you some occasion and assistance to
enquire; But I must not now stay to do so my self, only I shall take notice
to you, that though it be taken for granted that bodies will not be
Praecipitated by Alcalizat Salts, that have not first been dissolved in some
Acid _Menstruums_, yet I have found upon tryals, which my conjectures lead
me to make on purpose, That divers Vegetables _barely infus'd_, or, _but
slightly decocted in common water_, would, upon the affusion of a Strong
and Cleer _Lixivium_ of Potashes, and much more of some other Praecipitating
liquors that I sometimes employ, afford good store of a Crudled matter,
such as I have had in the Praecipitations of Vegetable substances, by the
intervention of Acid things, and that this matter was easily separable from
the rest of the liquor, being left behind by it in the Filtre; and in
making the first Ink mention'd in this Experiment, I found that I could by
Filtration separate pretty store of a very Black pulverable substance, that
remain'd in the Filtre, and when the Ink was made Cleer again by the Oyl of
Vitriol, the affusion of dissolv'd _Sal Tartari_ seem'd but to Praecipitate,
and thereby to Unite and render Conspicuous the particles of the Black
mixture that had before been dispers'd into very Minute and singly
Invisible particles by the Incisive and resolving power of the highly
Corrosive Oyl of Vitriol.
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