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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。
CHAPTER XIV。
CLASSIFICATIONS OF INK。
INK USED BY US HAS NOTHING IN COMMON WITH THAT
OF THE ANCIENTSMANUFACTURERS OF THE PRESENT
TIME HAVE LARGELY UTILIZED FORMULAS EMPLOYED
IN PAST CENTURIESTHE COMMON ACCEPTATION OF
THE TERM INKSEVEN DIFFERENT CLASSES OF INKS
AND THEIR COMPOSITION BRIEFLY TOLDFAILURE OF
EFFORTS TO SECURE A REAL SAFETY INK。
THE inks used by us have nothing in common with
those of the ancients except the color and gum； and
mighty little of that。
Those of the 〃gall〃 class employed in the fourteenth；
fifteenth； sixteenth； seventeenth and eighteenth
centuries； some formulas of which are utilized
by the manufacturers of ink in our own time； consisted
generally in combination； infusions of nut…galls； sulphate
of copper or iron； or both； and fish…glue or gum；
slightly acidulated。 The frequent introduction of the
so…called 〃added〃 color into these inks； time has shown
to have been a grave mistake。
The common acceptation of the term 〃ink〃 may be
said to characterize an immense number of fluid compounds；
the function of which in connection with a
marking instrument is to delineate conventional signs；
characters and letters as put together and commonly
called writing； on paper or like substances。
To classify them would be impossible； but black
writing ink； chemical writing fluid； colored writing
ink； copying ink； India ink； secret or sympathetic ink；
and indelible ink make seven classes； the others may
be denominated under the head of miscellaneous inks；
and of them all； there is no single ink answering every
requirement and few answer at all times the same requirements。
Ink may be either a clear solution of any
coloring matter or of coloring matter held in suspension。
It is a remarkable fact that although most inks
are chemical compositions and many times made after
the same formula； identical results cannot always be
calculated or obtained。 This is more particularly to be
noted in the case of black writing inks otherwise
known as the tanno…gallate of iron inks ＇gallic and gallotanic
acid obtained from nut…galls； sulphate of iron；
（green copperas） and some gummy vehicle＇。
The variations would appear to be largely due to the
difference in quality of the gall…nuts； treatment； and
temperature of the atmosphere； perhaps； however； not
so much to…day as it was ten or twenty years ago；
when to make ink of this character boiling processes
were employed。 Most of them as already stated are
now 〃cold〃 made。
Inks of this class consist of a finely divided insoluble
precipitate suspended in water by the use of gum and
possessing a slight acidity。
The requisites of a good black writing ink or
black writing fluid require it to flow readily from
the pen； to indicate in a short time a black color
and to penetrate the paper to an appreciable
degree； and more important than all the rest； to be of
great durability。 When kept in a closed vessel no
sediment of any account should be precipitated； although
such will be the case in open ink…wells； and
this the quicker the more the air is permitted to get
to it。 If it is to be used for record or documentary
purposes it must not be altogether obliterated if brought
into contact with water or alcohol； and should depend
for permanency on its chemical and not on its pigmentary
qualities。
The second class； called for distinction 〃chemical
writing fluids；〃 possesses the same essential ingredients
to be found in class one； but much less in
quantity and with some 〃added〃 colored substance
which I shall term 〃loading；〃 for its real purpose is to
cheapen the cost of production and not altogether as
some manufacturers state 〃simply to give them an
agreeable color。〃
Previous to the discovery of the soluble anilines；
logwood； indigo； madder； orchil and other dyeing
materials were used for a period of some eighty years
and vanadium for some twenty years （very costly
at that time）； for this purpose； but since 1874； and
with frequent changes as the newer aniline compounds
were invented； these by…products of coal…tar； as well as
logwood； etc。； have been and are to…day employed for
〃loading；〃 or as the manufacturer expresses； it 〃added
color。〃 The chemical writing fluids as now prepared；
yield when first written a blue or green color with a
tendency to change to black afterwards。 They are
not as permanent as those of the first class。
Another black ink not durable； however； is 〃logwood；〃
its extract is combined with a little chromate
of potassium and boiled together in water。 It possesses
its own 〃gum〃 and contains some tannin。 In
combination with alum and water； it forms a dark
purple ink。
The colored writing inks； of which 〃red〃 is the
more important； are in great number and with hardly
an exception at the present time； manufactured by
adding water and water…glass to a soluble aniline red
color。 Cochineal which was used for red ink formerly
is now almost obsolete。 Nigrosine； one of the best
known of them； is much used as a cheap 〃black〃 ink；
but as it is blue black and never becomes black； it
really belongs to the family of 〃colored〃 writing
inks。 They possess an undeserved popularity for they
flow freely from the pen which they do not corrode；
nor do they thicken or spoil in the inkwell； they are
however very 〃fugitive〃 in character and should not
be employed for record； legal； monetary or other
documentary purposes。 The indigo and prussian blue
inks are well known； the former under certain conditions
a very permanent ink； the latter soon disintegrating。
Copying inks are of two kinds； one dependent on
the addition of glycerine； sugar； glucose or like compounds
to the black writing inks or chemical writing
fluids heretofore mentioned； which are thereby kept
in a moist offsetting condition； the other due to the
solubility of the pigmentary color with water； such as
the aniline inks which are given mor