STUDY OF INK.
INVESTIGATIONS BY STARK OF INK QUALITIES COVERING
A PERIOD OF TWENTY-THREE YEARS--ABSTRACT FROM
HIS REPORT OF 1855--DR. CHILTON EXPERIMENTS IN
NEW YORK CITY 1856--ACTION OF THE PRUSSIAN
GOVERNMENT IN 1859 AND EMPLOYMENT OF AN OFFICIAL
INK--WATTENBACH'S GERMAN TREATISE ON THE
ARCHIVES OF THE MIDDLE AGES--WILLIAM INGLIS
CLARK ATTEMPTS TO PLACE THE MANUFACTURE OF INK
ON A SCIENTIFIC BASIS--SUBMITS HIS VALUABLE
RESEARCHES AND DEDUCTIONS TO THE ENINBURGH
UNIVERSITY IN 1879--SCHLUTTIG AND NEUMANN IN
1890 ESTABLISH A STANDARD FORMULA FOR IRON
AND GALL INK--NAMES OF SOME INK INVESTIGATORS
OF THE NINETEENTH CENTURY.
DR. JAMES STARK, a famous chemist, submitted the
results of twenty-three years of investigations of writing
inks in a paper read by him in 1855 before the
Society of Arts, in Edinburg, Scotland. The following
is the abstract as printed by the London Artisan
at the time:
"The author stated that in 1842 he commenced
a series of experiments on writing inks, and up to
this date (1855), had manufactured 229 different
inks, and had tested the durability of writings made
with these on all kinds of paper. As the result
of his experiments be showed that the browning
and fading of inks resulted from many causes,
but in ordinary inks chiefly from the iron becoming
peroxygenated and separating as a heavy
precipitate. Many inks, therefore, when fresh made,
yielded durable writings; but when the ink became
old, the tanno-gallate of iron separated, and
the durability of the ink was destroyed. From a
numerous set of experiments the author showed
that no salt of iron and no precipitate of iron
equalled the common sulphate of iron--that is,
the commercial copperas--for the purpose of ink-
making; and that even the addition of any persalt,
such as the nitrate or chloride of iron, though
it improved the present color of the ink, deteriorated
its durability. The author failed to procure
a persistent black ink from manganese, or other
metal or metallic salt. The author exhibited a series
of eighteen inks which had either been made
with metallic iron or with which metallic iron had
been immersed, and directed attention to the fact
that though the depth and body of color seemed to
be deepened, yet in every case the durability of
writings made with such inks was so impaired that
they became brown and faded in a few months.
The most permanent ordinary inks were shown to
be composed of the best blue gall nuts with copperas
and gum, and the proportions found on experiment
to yield the most persistent black were
six parts of best blue galls to four parts of copperas.
Writings made with such an ink stood exposure
to sun and air for twelve months without
exhibiting any change of color, while those made
with inks of every other proportion or composition
had more or less of their color discharged when
similarly tested. This ink, therefore, if kept from
moulding and from depositing its tanno-gallate of
iron, would afford writings perfectly durable. It
was shown that no gall and logwood ink was equal
to the pure gall ink in so far as durability in the
writings was concerned. All such inks were exhibited
which, though durable before the addition
of logwood, faded rapidly after logwood was added
to them. Sugar was shown to have an especially
hurtful action on the durability of inks containing
logwood--indeed, on all inks. Many other plain
inks were exhibited, and their properties described
--as gallo-sumach ink, myrabolams ink, Runge's ink,
--inks in which the tanno-gallate of iron was kept
in solution by nitric, muriatic, sulphuric, and other
acids, or by oxalate of potash, chloride of lime,
etc. The myrabolams was recommended as an ink
of some promise for durability, and as the cheapest
ink it was possible to manufacture. All ordinary
inks, however, were shown to have certain drawbacks,
and the author endeavored to ascertain by
experiment whether other dark substances could be
added to inks to impart greater durability to writings
made with them, and at the same time prevent
those chemical changes which were the cause of ordinary
inks fading. After experimenting with various
substances, and among others with Prussian
blue and indigo dissolved in various ways, he found
the sulphate of indigo to fulfil all the required
conditions and, when added in the proper proportion
to a tanno-gallate of iron ink, it yielded an ink
which is agreeable to write with, which flows freely
from the pen and does not clog it; which never
moulds, which, when it dries on the paper, becomes
of an intense pure black, and which does not fade
or change its color however long kept. The author
pointed out the proper proportions for securing those
properties, and showed that the smallest quantity
of the sulphate of indigo which could be used for
this purpose was eight ounces for every gallon of
ink. The author stated that the ink he preferred
for his own use was composed of twelve ounces of
gall, eight ounces of sulphate of indigo, eight
ounces of copperas, a few cloves, and four or
six ounces of gum arabic, for a gallon of ink.
It was shown that immersing iron wire or filings
in these inks destroyed ordinary inks. He
therefore recommended that all legal deeds or
documents should be written with quill pens, as the
contact of steel invariably destroys more or less
the durability of every ink. The author concluded
his paper with a few remarks on copying inks and
indelible inks, showing that a good copying ink has
yet to be sought for, and that indelible inks, which
will resist the pencilings and washings of the chemist
and the forger, need never be looked for."
Professor Leonhardi, of Dresden, who had given much
attention to the subject of inks, introduced in 1855
what he termed a NEW ink, and named it "alizarine
ink," alizarin being a product obtained from the madder
root, which he employed for "added" color in a
tanno-gallate of iron solution. It possessed some
merit due to its fluidity, and for a time was quite popular,
but gradually gave place to the so-called chemical
writing fluids; it is now obsolete.
Champour and Malepeyre, Paris, 1856, issued a
joint manual, "Fabrication des Encres," devoted almost
exclusively to the manufacture of inks and compiles
many old "gall" and other ink formulas.
In 1856 Dr. Chilton of New York City published
the results of ink experiments which he had made.
The accompanying extracts are taken from the local
press of the month of April of that year:
"Some ingenious experiments to test the durability
of writing inks have recently been made by
Dr. Chilton, of New York City. He exposed a
manuscript written with four different inks of the
principal makers, of this and other countries, to the
constant action of the weather upon the roof of his
laboratory. After an exposure of over five months,
the paper shows the different kind of writing in
various shades of color. The English sample,
Blackwood's, well known and popular from the
neat and convenient way that it is prepared for
this market, was quite indistinct.
"The American samples, David's, Harrison's
and Maynard's are better. The first appears to
retain its original shade very neatly; the two last
are paler. This test shows conclusively the durability
of ink; and while, for many purposes, school
and the like, an ink that will stand undefaced a
year or so, is all that is necessary, yet there is
hardly a bottle of ink sold, some of which may not
be used in the signature or execution of papers that
may be important to be legible fifty or one hundred
years hence.
"For state and county offices, probate records,
etc., it is of vital importance that the records should
be legible centuries hence. We believe that some
of the early manuscripts of New England are
brighter than some town and church records of this
century.
"In Europe at the present time, great care is
taken by the different governments in the preparation
of permanent ink--some of them even compounding
their own, according to the most approved
and expensive formulas.
"Manuscripts of the eleventh and twelfth centuries
now in the state paper office of Great Britain,
are apparently as bright as when first written;
while those of the last two hundred years are more
or less illegible, and some of them entirely obliterated."
While the information sought to be conveyed in the
last statement may be in some respects correct, it must
be remembered that most of the MSS. extant dating before
the thirteenth century were written in "Indian"
ink, while the great majority of those of the last two
hundred years were not; and this fact alone would
account to some extent for the differences mentioned.
The German (Prussian) government in 1859, as the
result of an investigation, employed what they termed
"Official Ink of the First Class," i. e., a straight tanno-
gallate of iron ink without added color; and if permanence
were required as against removal by chemicals,
it was accomplished by writing on paper saturated
with chromates and ultramarine.
In 1871 Professor Wattenbach of Germany published
a treatise entitled "Archives during the Middle
Ages," which has some valuable references to the color
phenomena of inks.
William Inglis Clark in 1879 submitted to the Edinburgh
University a thesis entitled "An Attempt to
Place the Manufacture of Ink on a Scientific Basis,"
and which very justly received the commendation of
the University authorities. His researches and rational
deductions are of the greatest possible value
judged from a scientific standpoint. The introduction
of blue-black ink is a phase of the development towards
modern methods which he discusses at much
length.
The object of adding a dye in moderation, he
asserts, is to give temporary color to the ink and
where indigo-paste is used, it has been assumed that
it kept the iron gallo-tannate in solution, whereas any
virtue of this kind which indigo-paste possesses is
more likely due to the sulphuric acid which it contains
than to the indigo itself. The essential part of the
paste required is the sulpho-indigodate of sodium, now
commonly called indigo-carmine. He further remarks
that the stability of an ink precipitate depends upon
the amount of iron which it contains and which on no
account should be less than eight per cent; he adds
rightly, if gallic acid be preferably used in substitution
for tannin, "no precipitate is obtained under
precisely similar conditions." This point followed up
explains in a measure why a gall infusion prepared
with hot water is not suitable for a blue-black, while
a cold water infusion is. In the latter case a
comparatively small percentage of tannin is extracted
from the galls, while much is extracted with hot water
and the consequence is, on adding the indigo blue the
color is not brought out as it should be. Substantially
the same thing occurs with ink made with the respective
acids, although the blue color remains for a time unimpaired
in the tannin ink, apparently due to the fact that
ferrous-tannate reduces indigo blue to indigo white, a
change which the low reducing power of ferrous-
gallate does little to effect. The vegetable matter in
common inks facilitates the destruction, or rather
alteration and precipitation of the indigo, for the dye
appears in the iron precipitate and may be extracted
from it with boiling water.
Dr. Clark's investigations seek to demonstrate the
superiority of tannin and gallic acid over infusions of
the natural galls, and he undertakes to determine the
correct ratio of tannin and sulphate of iron to be used
as ink. His experiments in this line show that:
1. The amount of precipitate increases as the proportion
of iron to tannin is increased.
2. The composition of the precipitate is so valuable
as to preclude the possibility of its being a definite
body. Increase of iron in the solution has not at first
any effect on the composition of the precipitate, but
afterwards iron is found in it in greater but not proportional
amount.
3. At one point the proportions of iron in the precipitate
and in solution are the same, and this is at
between 6 and 10 parts of iron to 100 parts of tannin.
4. The proportion of iron in the precipitate varies
greatly with the length of time the ink has been exposed.
At first the precipitate contains 10 per cent
of iron, but by and by a new one having only 7.5
per cent is formed, and in from forty to seventy days
we find one of 5.7 per cent. Simultaneously iron increases
in the ink (proportionate to the tannin).
5. The results show, and practice confirms, that
16 parts of iron (80 ferrous sulphate) and 100 parts of
tannin are best for ink manufacture.
The research now travelled in a direction which
accumulating experience showed to be obligatory.
Blue-black tannin ink lost color, and the reducing
nature of the tannin tended to the formation of a
highly objectionable precipitate in the ink, which
made writing anything but a pleasure. These two
faults were doubtless linked together in some way
and seemed not to exist when gallic acid was used,
for ink so made was found to precipitate only after
a long exposure, it required no free acid to keep the
precipitate in solution, and retained the indigo blue
color for a long time; alkalis did not decompose the
ink, and provided blacker and more permanent writing.
Determination of the correct proportions of
gallic acid and ferrous-sulphate was the subject of prolonged
experiments conducted on similar lines to those
already detailed. The conclusions as to precipitation
were also similar. Thirty parts of iron (150 of ferrous-
sulphate) and 100 parts of gallic acid were found to
be the most suitable proportions for ink-making. It
is advisable, however, not to discard tannin altogether,
owing to the slow blackening of the gallic acid ink,
and a little tannin gives initial blackening and body,
while it is absolutely necessary for copying ink.
Initial blackness can also be ensured by oxidizing
21 per cent of the ferrous-sulphate without adding
the extra acid necessary to the formation of a ferric
salt.
The concluding portion of his research is devoted
to the influence of sugar upon the permanence of ink,
and the results of the experiments are summed up in
the following sentences: "It would be injurious to
add 3 per cent of sugar to a tan in ink, while from
4 to 10 per cent would be quite allowable. Most
copying inks contain about 3.5 per cent of sugar--
not far from the critical amount. With gallic acid
more than 3 per cent of sugar hardly varies the precipitate,
but the importance of this point is somewhat
diminished by the fact that the presence of sugar is
by no means necessary in a writing ink. Dextrin is
a much superior substance to use. Curiously this
body rapidly precipitates a tannin ink; hence it is
useless for copying ink, but for the gallic ink it is an
excellent thickener."
Chen-Ki-Souen, "Lencre de China," by Maurice Jametel,
appeared in Paris in 1882, but as the title indicates,
it is the old "Indian" or Chinese ink that is discussed.
Schluttig and Neumann in 1890 issued their
Edition Dresden on the subject of "Iron and Gall
inks." In this valuable work is to be found the
formula which has been generally adopted as the
standard where one is used for tanno-gallate of iron ink.
The investigations of other scientific men like Lepowitz,
Booth, Desormeaux, Chevreuse, Irvine, Traille,
Bottger, Riffault, Precht, Nicholes, Runge, Gobert,
Penny, Arnold, Thomson (Lord Kelvin), Davids, Kindt,
Ure, Wislar and many more who have dealt with the
chemistry of inks, present to us some testimony during
a considerable portion of the nineteenth century
of the efforts made to secure a good ink.