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discovered part at least of the problem would be；
simplified。
The 〃added〃 color compounds； excluding those of
the aniline family which pertain to the more modern
ink compositions； are of two classes： those possessing
tannin and color…yielding materials and those containing
only a color…yielding material。 Many of the first
class have been used in the manufacture of ink both
with infusions of nut…galls or alone； while but very
few of the second class have been used for either purpose。
The decomposing action of light； oxygen and
moisture on many of each class placed them beyond
the purview of consideration； while the dates of the
discovery and the fact of the small percentage of tannin
contained in others permitted them also to be
discarded。 For instance： vanadium； which is fairly
permanent； was discovered only in 1830； chanchi； the
ink plant of New Granada discovered in the sixteenth
century； possessing excellent lasting qualities； does not
assimilate perfectly with other constituents used in the
manufacture of ink； but is best when used alone；
Berlin blue （prussian blue） is well spoken of； but
was only discovered by accident in 1710 by Diesbach；
a preparer of colors at Berlin； logwood； more used
for this purpose than any other material； was first
imported into Europe in the sixteenth century and
causes a deterioration of the durable qualities of the
tanno…gallate of iron； Brazil…wood and archil； and
their allies； are exceedingly fugitive； bablah； the
fruit of the acacia arabica； myrabolams； of Chinese
growth； catechu； and sumac which though used in
the time of Pliny； each contains a percentage of
gallic acid too small to meet the requirements。
Divi…divi； a South American product； came into use
only at the end of the sixteenth century and has not
stood the test of time。
This sifting process completely eliminated all but
lampblack； madder and indigo in some form as a
permanent 〃added〃 color pigment。 Lampblack；
which is we know forms the basis of 〃Indian〃 ink；
is not soluble and requires a very heavy gummy
vehicle to prevent its immediate precipitation； and
while it could have been used in combination with
tanno…gallate of iron as an ink； the fact that it was
possible to chemically remove the ancient inks which
remained black； was a sufficient demonstration that
this carbon substance； which is not affected by chemicals；
either as contained in the fluid ink or as dusted
on after writing； could have formed no part of the
ancient tanno…gallate of iron inks。
Madder is mentioned as of very ancient times and
was cultivated in Europe as early as the tenth century；
its addition to an iron and gall ink is said to be
an invention of the year 1855； it is certain； however；
that it was used for a like purpose as early as 1826；
and a fair presumption that it was frequently
employed in some form during the preceding four
centuries。 It has under certain conditions very lasting
properties as the madder…dyed cloths found
wrapped around Egyptian mummies demonstrates；
but does not assist the tanno…gallate of iron to retain
its black color； on the contrary it seems to lessen this
quality。
That indigo for added color was employed by ink
manufacturers in the eighteenth century is shown by
the formulas appearing in the literature of that time。
It was used alone as an ink long before； as well as
contemporaneously with； those of the tanno…gallate of
iron family。 Its lasting properties are most remarkable
if it be true that； used as a dye； there is still in
existence specimens of it on cloth five thousand or
more years old。 The history of its use ALONE as an
ink is difficult to ascertain back of a certain period；
the writer has several specimens of it； one written in
1692 whose color is a green blue； another written
about a century ago is believed to be as bright blue
as the day it was placed on the paper； from 1810 to
1850 it was in common use particularly in hot
climates where it was 〃home…made。〃 Consequently
if the old 〃gall〃 inks contained a lasting added
color； indigo must have been the one； Dr。 Stark
whose investigations along this line for twenty…three
years have already been cited has said that he
preferred for his own use an ink composed of galls；
sulphate of indigo and copperas （sulphate of iron）；
this means a tanno…gallate of iron ink with indigo for
〃added〃 color。 Like formulas calling for different
proportions of constituents both before and after his
time in England and the continents of Europe and
America are to be found in considerable number；
proving that its use was more or less constant in this
respect。 To determine； then； whether or not the
blacker specimens of the ancient writings contained
indigo in any of its forms was most important； and
the plan adopted most simple。 Specimens of writing
in ink of which the manufacturer's name was known
as well as his formula and only thirty years old
showed evidence of considerable 〃browning；〃 some
of them when tested in juxtaposition with those of
from fifty to one hundred years old which had turned
completely brown； gave approximately the same results；
and differentiated largely from the results obtained
from jet black specimens of eighty to five
hundred or more years of age。 In a number of the
browner ones indigo was found to be present while in
many of the black ones it was not； demonstrating
that the reason for the continuing blackness of the
older inks is not due to an added color or pigment of
any kind and furthermore that the 〃Stark〃 and
corresponding ink formulas after the test of TIME did not
retain their original blackness but deteriorated to a
brown color； moreover； that their purpose as in the
present day was to give an agreeable and immediate
color result； a free…flowing ink； and to cheapen the
cost of manufacture when compared with that of an
unadulterated tanno…gallate of iron ink。
No disagreement being now possible as to the lasting
color virtues of a properly proportioned tanno…
gallate of iron ink WITHOUT an 〃added〃 color or
pigment； there remained the sole question as to the
vehicle utilized to hold this combination in suspension
and whether or not it had to do with the continuing
blackness of the older inks。
The answer must lie between the vegetable product
known as gum and the animal product known as
gelatine。 The first disintegrates； quickly absorbs
moisture and gradually disappears； while gelatine
（isinglass） 〃contains under conditions 50％ carbon；
although its molecular formula has not yet been
determined。 It cannot be converted into vapor and
does not form well…defined compounds with other
bodies； it is insoluble in alcohol which precipitates it
in flakes from its aqueous solution。 It is also precipitated
by tannin； which combines with it to form
an insoluble non…putrescible compound。 Gallic acid；
however； does not precipitate it。〃 （Bloxam。）
Possess