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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 more body than
those for ordinary purposesand the logwoods in
which the pigment is developed and given copying
qualities by chemicals； and hence becomes responsive
to the application of a sheet of paper dampened with
water。 Copying ink should never be used for
〃record〃 purposes as it is affected by changes of the
temperature。
India ink； sometimes called China ink； or as formerly
known by the ancients and in classical and later times
〃Indian ink；〃 is now used more for drawing and engrossing
than it is for commercial purposes。 It belongs
to the 〃carbon〃 class and in some form was
the first one used in the very earliest times。 In
China it is applied with a brush or pith of some reed
to the 〃rice〃 paper also there manufactured。 It is
easily washed away unless bichromate of ammonium
or potassium in minute quantities be added to it； and
then if the paper on which it appears be exposed for a
short time to the action of the actinic rays of sunlight；
this gummy compound will be rendered insoluble and
cannot be removed with any fluid； chemical or otherwise。
It possesses also great advantages in drawing；
since it acts as a paint； and will give any degree of
blackness according to the quantity of water mixed with it。
Secret or sympathetic inks are invisible until the
writing is subjected to a subsequent operation； such
as warming or exposing to sunlight。 To further aid
the object in view； the paper may be first steeped in
a liquid and the writing only made visible by using
another liquid which has some chemical affinity with
the previous one。 The number of this kind were but
few but have multiplied as chemistry progressed。
The ancients were acquainted with several modes。
Ovid indiscreetly advises the Roman wives and maidens
if they intend to make their correspondence unreadable
to the wrong persons to write with new milk；
which when dried may be rendered visible by rubbing
ashes upon it or a hot iron。 Pliny suggests milky
juices of certain plants of which there are a considerable
variety。
Indelible ink is not used for writing purposes on
paper； but is found best adapted for marking linen
and cancellation or endorsing purposes。 It is chiefly
composed of nitrate of silver preparations； to which
heat must be applied after it has been dried； or a
pigment is commingled with the same vehicles used
in making common printing ink and in its use treated as such。
Diamonds； gold； silver； platinum and a host of other
materials are manufactured into ink and are to be
placed under the head of miscellaneous inks。 They
are in great number and of no interest in respect to
ink writing except for engrossing or illuminating。
Still another ink once held in much esteem and now
almost obsolete is the so…called 〃safety〃 ink。
Manufacturers； chemists and laymen in great number
for many years wasted money； time and energy
in diligent worship at a secret shrine which could not
give the information they sought。 A summary of the
meager and barren results they secured is of little
value and unimportant。 Hence； there is no REAL 〃safety〃 ink。
It is true that lampblack （carbon） as made into
ink； resists any chemical or chemicals； but simple
water applied on a soft sponge will soon remove such
ink marks。 The reason for this is obvious； the ink
does not penetrate the paper。
〃Safety〃 ink which will not respond to acids may
be affected by alkalis； or if resisting them separately；
will yield to them in combination。
CHAPTER XV。
OFFICIAL AND LEGAL INK。
FIRST COMPLETE OFFICIAL INVESTIGATION OF INK IN
THIS COUNTRYTHE HONOR DUE TO ROBERT T。 SWAN
OF BOSTONRESUME OF HIS REPORTS TO THE
LEGISLATURE OF THE STATE OF MASSACHUSETTSTHE
SWAN LAW ADOPTED IN 1894 BY THE STATE OF
MASSACHUSETTSUNITED STATES TREASURY DEPARTMENT
ADOPTS AN OFFICIAL INK IN 1901UNSUCCESSFUL
ATTEMPT TO SECURE INK LEGISLATION IN THE STATE
OF NEW YORKCOMMENTS OF THE PUBLIC PRESS OF
THAT PERIODDIFFERENT WORKS WHICH MORE OR
LESS DWELL ON THE SUBJECT OF INK FROM 1890 TO
1900CITATIONS FROM ALLEN'S COMMERCIAL ORGANIC
ANALYSISREFERENCE TO PAPER ABOUT INK
READ BEFORE THE NEW YORK STATE BAR ASSOCIATION。
IT was not； however； until 1891 that the subject of
the constitution of an enduring record ink received
the consideration its importance deserved and in this
the youngest of countries。 To Robert T。 Swan of
Boston is all honor due for the very unique and
comprehensive methods adopted in his investigations。
Appointed 〃commissioner of public records〃 of the
state of Massachusetts； he has set an example which
may well be followed by other states； as has been
done in a lesser degree by Connecticut and ten years
later by the United States Treasury Department；
which in this respect is so ably represented in part
by Dr。 Charles A。 Crampton of Washington； D。