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forty centuries of ink-第62章

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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
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