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numerous； being carbon and nitrate of ammonia；
carburetted and sulphuretted hydrogen； and water；
and these ammoniacal salts greatly favor the growth
of fungi。 Now paper consists essentially of woody
fibre； having animal matter as size on its surface。
The first microscopic symptom of decay in paper is
irregularity of surface； with a slight change of color；
indicating the commencement of the process just
noticed； during which； in addition to carbonic acid；
certain organic acids are formed； as crenic and ulmic
acids； which； if the paper has been stained by
a coloring matter； will form spots of red on the
surface。 The same process of decay goes on in
parchment as in paper； only with more rapidity；
from the presence of nitrogen in its composition。
When this decay has begun to take place； fungi are
produced； the most common species being
Penicilium glaucum。 They insinuate themselves between
the fibre； causing a freer admission of air； and
consequently hasten the decay。 The substances most
successfully used as preventives of decay are the
salts of mercury； copper； and zinc。 Bichloride of
mercury （corrosive sublimate） is the material employed
in the kyanization of timber； the probable
mode of action being its combination with the albumen
of the wood； to form an insoluble compound
not susceptible of spontaneous decomposition； and
therefore incapable of exciting fermentation。 The
antiseptic power of corrosive sublimate may be
easily tested by mixing a little of it with flour
paste； the decay of which； and the appearance of
fungi； are quite prevented by it。 Next to corrosive
sublimate in antiseptic value stand the salts of
copper and zinc。 For use in the preservation of
paper the sulphate of zinc is better than the chloride；
which is to a certain extent delinquescent。〃
There are numerous paper tests which include the
matter of sizing； direction of the grain； absorbing
powers； character of ingredients； etc。 A few of them
are cited。
SIZING。The everyday tests as to hardness of
sizing answer every ordinary purpose： Moisten with
the tongue； and if the paper is slack…sized you can
detect it often by the instant drawing or absorption
of the moisture。 Watch the spot moistened； and the
longer it remains wet the better the paper is sized。
Look through the spot dampenedthe poorer the
sizing the more transparent is the paper where it is
wet。 If thoroughly sized no difference will be apparent
between the spot dampened and the balance
of the sheet。 When there is a question as to whether
a paper is tub or engine sized； it can be usually decided
by wetting the forefinger and thumb and pressing
the sheet between them。 If tub…sized； the glue
which is applied to the surface will perceptibly cling
to the fingers。
TO TEST THE INK RESISTING QUALITY OF PAPER。
Draw a heavy ink line across the sheet。 If the paper
is poorly sized； a feathery edge will appear； caused
by spreading of the ink。 Slack…sized paper will be
penetrated by the ink； which will plainly appear on
the reverse side of the sheet。
TO DETERMINE THE DIRECTION OF THE GRAIN。
An easy but sure test to determine the direction of
the grain in a sheet of paper； which will be found
useful and worth remembering； is as follows：
For instance； the size of sheet is 17x22 inches。
Cut out a circular piece as nearly round as the eye
can judge； before entirely detaching from the sheet；
mark on the circle the 17…inch way and the 22…inch
way； then float the cut out piece on water for a few
seconds； then place on the palm of the hand； taking
care not to let the edges stick to the hand； and the
paper will curl until it forms a cone； the grain of the
paper runs the opposite way from which the paper
curls。
ABSORBING POWERS OF BLOTTING PAPER。Comparative
tests as to absorbing powers of blotting
can be made between sheets of same weight per
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 sulp