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other observations were later shown to have been
erroneous。 Dr。 Lewis was the first to advocate log…
wood as a tinctorial agent in connection with iron and
gall compositions。
Ribaucourt； a French ink maker； in 1798 determined
that an excess of galls is quite as injurious to
the permanence of ink as an excess of iron。
Pending the completion of the researches of Lewis；
the Royal Society of England； affected by complaints
from all quarters relative to the inferiority of inks as
compared with those of earlier times； brought the
subject to the attention of many of its members for
discussion and advice。 Its secretary； Charles Blagden；
M。 D。； read a paper before the society； June 28； 1787；
which was published in the 〃Philosophical Transactions〃
and widely circulated。 It is so interesting that
copious extracts are given：
〃In a conversation some time ago with my friend
Thomas Astle； Esq。； F。 R。 S。 and A。 S。； relative
to the legibility of ancient MSS。 a question arose；
whether the inks in use eight or ten centuries ago；
which are often found to have preserved their colour
remarkably well； were made of different materials
from those employed in later times； of which many
are already become so pale as scarcely to be read。
With a view to the decision of this question； Mr。
Astle obligingly furnished me with several MSS。；
on parchment and vellum； from the ninth to the
fifteenth centuries inclusively； some of which were
still black； and others of different shades of colour；
from a deep yellowish brown to a very pale yellow；
in some parts so faint as to be scarcely visible。 On
all of these I made experiments with the chemical
re…agents which appeared to me best adapted to
the purpose； namely； alkalis both simple and phlogisticated；
the mineral acids； and infusions of galls。
〃It would be tedious and superfluous to enter into
a detail of the particular experiments； as all of
them； one instance only excepted； agreed in the
general result； to shew that the ink employed
anciently； as far as the above…mentioned MSS。
extended； was of the same nature as the present；
for the letters turned of a reddish or yellow brown
with alkalis； became pale； and were at length
obliterated； with the dilute mineral acids； and the
drop of acid liquor which had extracted a letter；
changed to a deep blue or green on the addition of
a drop of phlogisticated alkali； moreover； the letters
acquired a deeper tinge with the infusion of
galls； in some cases more； in others less。 Hence
it is evident； that one of the ingredients was iron；
which there is no reason to doubt was joined with
the vitriolic acid； and the colour of the more perfect
MSS。 which in some was deep black； and in others
purplish black； together with the restitution of that
colour； in those which had lost it； by the infusion
of galls； sufficiently proved that another of the ingredients
was a stringent matter； which from history
appears to be that of galls。 No trace of a black
pigment of any sort was discovered； the drop of
acid which had completely extracted a letter； appearing
of an uniform pale ferrugineous color； without
an atom of black powder； or other extraneous
matter； floating in it。
〃As to the durability of the more ancient inks；
it seemed； from what occurred to me in these experiments；
to depend very much on a better preparation
of the material upon which the writing was
made； namely； the parchment or vellum； the blackest
letters being those which had sunk into it
deepest。 Some degree of effervescence was commonly
to be perceived when the acids came into
contact with the surface of these old vellums。 I
was led； however； to suspect； that the more modern；
for in general the tinge of colour； produced by the
phlogisticated alkali in the acid laid upon them；
seemed less deep； which； however； might depend
in part upon the length of time they have been
kept： and perhaps more gum was used in them；
or possible they were washed over with some kind
of varnish； though not such as gave gloss。
〃One of the specimens sent me by Mr。 Astle；
of the fifteenth century； and the letters were those
of an engrossing hand； angular； without any FINE
strokes； broad and very black。 On this none of
the above…mentioned re…agents produced any considerable
effect； most of them seemed to make the
letters blacker； probably by cleaning the surface；
and the acids； after having been rubbed strongly on
the letters； did not strike any deeper tinge with the
phlogisticated alkali。 Nothing had a sensible effect
toward obliterating these letters but what took off
part of the surface of the vellum； when small rolls；
as of a dirty matter； were to be perceived。 It is
therefore unquestionable； that no iron was used in
this ink； and from its resistance to the chemical
solvents； as well as a certain clotted appearance in
the letters when examined closely； and in some
places a slight degree of gloss； I have little doubt
but they were formed with a composition of a black；
sooty or carbonaceous powder and oil； probably
something like our present printer's ink； and am not
without suspicion that they were actually printed
（a subsequent examination of a larger portion of
this supposed MSS。 has shown that it is really a part
of a very ancient printed book）。
〃Whilst I was considering of the experiments
to be made； in order to ascertain the composition
of ancient inks； it occurred to me that perhaps one
of the best methods of restoring legibility to decayed
writing might be to join phlogisticated alkali
with the remaining calx of iron； because； as the
quantity of precipitate formed by these two substances
very much exceeds that of the iron alone；
the bulk of the colouring matter would thereby be
greatly augmented。 M。 Bergman was of opinion
that the blue precipitate contains only between a
fifth and a sixth part of its weight of iron； and
though subsequent experiments tend to show that；
in some cases at least； the proportion of iron is
much greater； yet upon the whole it is certainly
true； that if the iron left by the stroke of a pen
were joined to the colouring matter of phlogisticated
alkali； the quantity of Prussian blue thence
resulting would be much greater than the quantity
of black matter originally contained in the ink
deposited by the pen； though perhaps the body of
colour might not be equally augmented。 To bring
the idea to the test； I made a few experiments as
follows：
〃The phlogisticated alkali was rubbed upon the
bare writing in different quantities； but in general
with little effect。 In a few instances； however； it
gave a bluish tinge to the letters； and increased
their intensity； probably where something of an
acid nature had contributed to the diminution of
their colour。
〃Reflecting that when phlogisticated alkali forms
its blue precipitate with iron the metal is first usually
dissolved in an acid； I w