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ream by allowing the pointed corner of a sheet to
touch the surface of a drop of ink。 Repeat with each
sheet to be tested； and compare the height in each to
which the ink has been absorbed。 A well…made
blotting paper should have little or no free fibre dust
to fill with ink and smear the paper。
TEST FOR GROUND WOOD。Make a streak across
the paper with a solution of aniline sulphate or with
concentrated nitric acid； the first will turn ground
wood yellow； the second will turn it brown。 I give
aniline sulphate the preference； as nitric acid acts
upon unbleached sulphite； if present in the paper； the
same as it acts upon ground wood； viz。； turning it
brown。
Phloroglucin gives a rose…red stain on paper containing
（sulphite） wood pulp； after the specimen has been
previously treated with a weak solution of hydrochloric
acid。
About the end of the eighteenth century it became
necessary to make special papers denominated 〃safety
paper。〃 Their manufacture has continued until the
present day although much limited； largely because
of the employment of mechanical devices which seek
to safety monetary instruments。 Such safety papers
are of several kinds。
1。 Paper made with distinguishing marks to indicate
proprietorship； as with the Bank of England
water mark； to imitate which is a felony。 Or the
paper of the United States currency； which has silk
fibers united with the pulp； the imitation of which is
a felony。
2。 Paper made with layers or materials which are
disturbed by erasure or chemical discharge of written
or printed contents； so as to prevent fraudulent
tampering。
3。 Paper made of peculiar materials or color； to
prevent copying by photographic means。
A number of processes may be cited：
One kind is made of a pulp tinged with a stain
easily affected by chlorine； acids； or alkalis； and is
made into sheets as usual。
Water marks made by wires twined among the
meshes of the wire cloth on which the paper is
made。
Threads embodied in the web of the paper。
Colored threads systematically arranged were formerly
used in England for post…office envelopes and exchequer
bills。
Silken fibers mixed with the pulp or dusted upon
it in process of formation； as used in the United
States currency。
Tigere； 1817； treated the pulp of the paper； previous
to sizing； with a solution of prussiate of potash。
Sir Win。 Congreve； 1819； prepared a colored layer
of pulp in combination with white layers； also by
printing upon one sheet and covering it with an
outer layer； either plain or water…marked。
Glynn and Appel； 1821； mixed a copper salt in the
pulp and afterward added an alkali or alkaline salt to
produce a copious precipitate。 The pulp was then
washed and made into paper and thereafter dipped in
a saponaceous compound。
Stevenson； 1837； incorporated into paper a metallic
base such as manganese； and a neutral compound like
prussiate of potash； to protect writing from being tampered
with。
Varnham； 1845； invented a paper consisting of a
white sheet or surface on one or both sides of a colored
sheet。
Stones； 1851。 An iodide or bromide in connection
with ferrocyanide of potassium and starch combined
with the pulp。
Johnson； 1853； employed the rough and irregular
surface produced by the fracture of cast iron or other
brittle metal to form a water mark for paper by taking
an impression therefrom on soft metal； gutta…
percha； etc。； and afterward transferring it to the wire
cloth on which the paper is made。
Scoutteten； 1853； treated paper with caoutchoue
dissolved in bisulphide of carbon； in order to render
it impermeable and to prevent erasures or chemical
action。
Ross； 1854； invented water…lining or printing the
denomination of the note in colors while the pulp was
yet soft。
Evans； 1854； commingled a lace or open…work fabric
in the pulp。
Courboulay； 1856； mixed the pulp and applied to
the paper salts of iodine or bromine。
Loubatieres； 1857； manufactured paper in layers；
any or all of which might be colored； or have impressions
or conspicuous marks for preventing forgery。
Herapath； 1858； saturated paper during or after its
manufacture with a solution of a ferrocyanide； a ferriccyanide；
or sulphocyanide of potassium； sodium； or
ammonium。
Seys and Brewer； 1858； applied aqueous solutions
of ferrocyanide of potassium or other salts； which
formed an indelible compound with the ferruginous
base of writing ink。
Sparre； 1859； utilized opaque matter； such as prussian
blue； white or red lead； insoluble in water and
stenciled on one layer of the paper web； forming a
regular pattern； this was then covered by a second
layer of paper。
Moss； 1859； invented a coloring matter prepared
from burned china or other clay； oxide of chromium
or sulphur； and combined it with the pulp。
Barclay； 1859； incorporated with the paper：
1。 Soluble ferrocyanides； ferricyanides； and sulphocyanides
of various metals； by forming dibasic salts
with potassium； sodium； or ammonium； in conjunction
with vegetable； animal； or metallic coloring matters。
2。 Salts of manganese； lead； or nickel not containing
ferrocyanogen。
3。 Ferrocyanides； etc。； of potassium； sodium； and
ammonium； in conjunction with insoluble salts of
manganese； lead； or nickel。
Hooper； 1860。 Employed oxides of iron； either
alone or dissolved in an acid； and mixed with the
pulp。
Nissen； 1860。 Treated paper with a preparation of
iron； together with ammonia； prussiate of potash and
chlorine； while in the pulp or being sized。
Middleton； 1860。 Joined together one portion of a
bank note printed upon one sheet of thin paper and
the other part on another； the two were then cemented
together by india…rubber； gutta…percha； or other compound。
The interior printing could be seen through
its covering sheet； so that the whole device on the
note appeared on its face。
Olier； 1861。 Employed several layers of paper of
various materials and colors； the middle one was
colored with a deleble dye； whose color was changed
by the application of chemicals to the outer layer。
Olier； 1863。 Prepared a paper of three layers of
different thicknesses； the central one having an easily
removable color； and the external layers were charged
with silicate of magnesia or other salt。
Forster and Draper； 1864。 Treating paper during
or after manufacture with artificial ultramarine and
Prussian blue or other metallic compound。
Hayward； 1864。 Incorporated threads of fibrous
materials of different colors or characters into and
among the pulp。
Loewenberg； 1866。 Introduced prussiate of potash
and oxalic acid or such other alkaline salts or acids
into the pulp； in order to indicate fraud in the removal
of cancellation stamps or written marks。
Casilear； 1868。 Printed numbers on a fugitive
ground； t