forty centuries of ink-第21章

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substances；　and　among　others　with　Prussian

blue　and　indigo　dissolved　in　various　ways；　he　found

the　sulphate　of　indigo　to　fulfil　all　the　required

conditions　and；　when　added　in　the　proper　proportion

to　a　tanno…gallate　of　iron　ink；　it　yielded　an　ink

which　is　agreeable　to　write　with；　which　flows　freely

from　the　pen　and　does　not　clog　it；　which　never

moulds；　which；　when　it　dries　on　the　paper；　becomes

of　an　intense　pure　black；　and　which　does　not　fade

or　change　its　color　however　long　kept。　The　author

pointed　out　the　proper　proportions　for　securing　those

properties；　and　showed　that　the　smallest　quantity

of　the　sulphate　of　indigo　which　could　be　used　for

this　purpose　was　eight　ounces　for　every　gallon　of

ink。　The　author　stated　that　the　ink　he　preferred

for　his　own　use　was　composed　of　twelve　ounces　of

gall；　eight　ounces　of　sulphate　of　indigo；　eight

ounces　of　copperas；　a　few　cloves；　and　four　or

six　ounces　of　gum　arabic；　for　a　gallon　of　ink。

It　was　shown　that　immersing　iron　wire　or　filings

in　these　inks　destroyed　ordinary　inks。　He

therefore　recommended　that　all　legal　deeds　or

documents　should　be　written　with　quill　pens；　as　the

contact　of　steel　invariably　destroys　more　or　less

the　durability　of　every　ink。　The　author　concluded

his　paper　with　a　few　remarks　on　copying　inks　and

indelible　inks；　showing　that　a　good　copying　ink　has

yet　to　be　sought　for；　and　that　indelible　inks；　which

will　resist　the　pencilings　and　washings　of　the　chemist

and　the　forger；　need　never　be　looked　for。〃



Professor　Leonhardi；　of　Dresden；　who　had　given　much

attention　to　the　subject　of　inks；　introduced　in　1855

what　he　termed　a　NEW　ink；　and　named　it　〃alizarine

ink；〃　alizarin　being　a　product　obtained　from　the　madder

root；　which　he　employed　for　〃added〃　color　in　a

tanno…gallate　of　iron　solution。　It　possessed　some

merit　due　to　its　fluidity；　and　for　a　time　was　quite　popular；

but　gradually　gave　place　to　the　so…called　chemical

writing　fluids；　it　is　now　obsolete。



Champour　and　Malepeyre；　Paris；　1856；　issued　a

joint　manual；　〃Fabrication　des　Encres；〃　devoted　almost

exclusively　to　the　manufacture　of　inks　and　compiles

many　old　〃gall〃　and　other　ink　formulas。



In　1856　Dr。　Chilton　of　New　York　City　published

the　results　of　ink　experiments　which　he　had　made。

The　accompanying　extracts　are　taken　from　the　local

press　of　the　month　of　April　of　that　year：



〃Some　ingenious　experiments　to　test　the　durability

of　writing　inks　have　recently　been　made　by

Dr。　Chilton；　of　New　York　City。　He　exposed　a

manuscript　written　with　four　different　inks　of　the

principal　makers；　of　this　and　other　countries；　to　the

constant　action　of　the　weather　upon　the　roof　of　his

laboratory。　After　an　exposure　of　over　five　months；

the　paper　shows　the　different　kind　of　writing　in

various　shades　of　color。　The　English　sample；

Blackwood's；　well　known　and　popular　from　the

neat　and　convenient　way　that　it　is　prepared　for

this　market；　was　quite　indistinct。



〃The　American　samples；　David's；　Harrison's

and　Maynard's　are　better。　The　first　appears　to

retain　its　original　shade　very　neatly；　the　two　last

are　paler。　This　test　shows　conclusively　the　durability

of　ink；　and　while；　for　many　purposes；　school

and　the　like；　an　ink　that　will　stand　undefaced　a

year　or　so；　is　all　that　is　necessary；　yet　there　is

hardly　a　bottle　of　ink　sold；　some　of　which　may　not

be　used　in　the　signature　or　execution　of　papers　that

may　be　important　to　be　legible　fifty　or　one　hundred

years　hence。



〃For　state　and　county　offices；　probate　records；

etc。；　it　is　of　vital　importance　that　the　records　should

be　legible　centuries　hence。　We　believe　that　some

of　the　early　manuscripts　of　New　England　are

brighter　than　some　town　and　church　records　of　this

century。



〃In　Europe　at　the　present　time；　great　care　is

taken　by　the　different　governments　in　the　preparation

of　permanent　inksome　of　them　even　compounding

their　own；　according　to　the　most　approved

and　expensive　formulas。



〃Manuscripts　of　the　eleventh　and　twelfth　centuries

now　in　the　state　paper　office　of　Great　Britain；

are　apparently　as　bright　as　when　first　written；

while　those　of　the　last　two　hundred　years　are　more

or　less　illegible；　and　some　of　them　entirely　obliterated。〃



While　the　information　sought　to　be　conveyed　in　the

last　statement　may　be　in　some　respects　correct；　it　must

be　remembered　that　most　of　the　MSS。　extant　dating　before

the　thirteenth　century　were　written　in　〃Indian〃

ink；　while　the　great　majority　of　those　of　the　last　two

hundred　years　were　not；　and　this　fact　alone　would

account　to　some　extent　for　the　differences　mentioned。



The　German　（Prussian）　government　in　1859；　as　the

result　of　an　investigation；　employed　what　they　termed

〃Official　Ink　of　the　First　Class；〃　i。　e。；　a　straight　tanno…

gallate　of　iron　ink　without　added　color；　and　if　permanence

were　required　as　against　removal　by　chemicals；

it　was　accomplished　by　writing　on　paper　saturated

with　chromates　and　ultramarine。



In　1871　Professor　Wattenbach　of　Germany　published

a　treatise　entitled　〃Archives　during　the　Middle

Ages；〃　which　has　some　valuable　references　to　the　color

phenomena　of　inks。



William　Inglis　Clark　in　1879　submitted　to　the　Edinburgh

University　a　thesis　entitled　〃An　Attempt　to

Place　the　Manufacture　of　Ink　on　a　Scientific　Basis；〃

and　which　very　justly　received　the　commendation　of

the　University　authorities。　His　researches　and　rational

deductions　are　of　the　greatest　possible　value

judged　from　a　scientific　standpoint。　The　introduction

of　blue…black　ink　is　a　phase　of　the　development　towards

modern　methods　which　he　discusses　at　much

length。



The　object　of　adding　a　dye　in　moderation；　he

asserts；　is　to　give　temporary　color　to　the　ink　and

where　indigo…paste　is　used；　it　has　been　assumed　that

it　kept　the　iron　gallo…tannate　in　solution；　whereas　any

virtue　of　this　kind　which　indigo…paste　possesses　is

more　likely　due　to　the　sulphuric　acid　which　it　contains

than　to　the　indigo　itself。　The　essential　part　of　the

paste　required　is　the　sulpho…indigodate　of　sodium；　now

commonly　called　indigo…carmine。　He　further　remarks

that　the　stability　of　an　ink　precipitate　depends　upon

the　amount　of　iron　which　it　contains　and　which　on　no

account　should　be　less　than　eight　per　cent；　he　adds

rightly；　if　gallic　acid　be　preferably　used　in　substitution

for　tannin；　〃no　precipitate　is　obtained　under

precisely　similar　conditions。〃　This　point　followed　up

explains　in　a　measure　why　a　gall　infusion　prepared

with　hot　water　is　not　suitable　for　a　blue…black；　while

a　cold　water　infusion　is。　In　the　latter　case　a

comparatively　small　percentage　of　tannin　is　extracted

from　the　galls；　while　much　is　extracted　with　hot　water

and　the　consequence　is；　on　adding　the　indigo　blue　the

color　is　not　brought　out　as　it　should　be。　Substantially

the　same　thing　occurs　with　ink　made　with　the　respective

acids；　although　the　blue　color　remains　for　a　time　unimpaired

in　the　tannin　ink；　apparently　due　to　the　fact　that

ferrous…tannate　reduces　indigo　blue　to　indigo　white；　a

change　which　the　low　reducing　power　of　ferrous…

gallate　does　little　to　effect。　The　vegetable　matter　in

common　inks　facilitates　the　destruction；　or　rather

alteration　and　precipitation　of　the　indigo；　for　the　dye

appears　in　the　iron　precipitate　and　may　be　extracted

from　it　with　boiling　water。



Dr。　Clark's　investigations　seek　to　demonstrate　the

superiority　of　tannin　and　gallic　acid　over　infusions　of

the　natural　galls；　and　he　undertakes　to　determine　the

correct　ratio　of　tannin　and　sulphate　of　iron　to　be　used

as　ink。　His　experiments　in　this　line　show　that：



1。　The　amount　of　precipitate　increases　as　the　proportion

of　iron　to　tannin　is　increased。



2。　The　composition　of　the　precipitate　is　so　valuable

as　to　preclude　the　possibility　of　its　being　a　definite

body。　Increase　of　iron　in　the　solution　has　not　at　first

any　effect　on　the　composition　of　the　precipitate；　but

afterwards　iron　is　found　in　it　in　greater　but　not　proportional

amount。



3。　At　one　point　the　proportions　of　iron　in　the　precipitate

and　in　solution　are　the　same；　and　this　is　at

between　6　and　10　parts　of　iron　to　100　parts　of　tannin。



4。　The　proportion　of　iron　in　the　precipitate　varies

greatly　with　the　length　of　time　the　ink　has　been　exposed。

At　first　the　precipitate　contains　10　per　cent

of　iron；　but　by　and　by　a　new　one　having　only　7。5

per　cent　is　formed；　and　in　from　forty　to　seventy　days

we　find　one　of　5。7　per　cent。　Simultaneously　iron　increases

in　the　ink　（proportionate　to　the　tannin）。



5。　The　results　show；　and　practice　confirms；　that

16　parts　of　iron　（80　ferrous　sulphate）　and　100　parts　of

tannin　are　best　for　ink　manufacture。



The　research　now　travelled　in　a　direction　which

accumulating　experience　showed　to　be　obligatory。

Blue…black　tannin　ink　lost　color；　and　the　reducing

nature　of　the　tannin　tended　to　the　formation　of　a

highly　objectionable　precipitate　in　the　ink；　which

made　writing　anything　but　a　pleasure。　These　two

faults　were　doubtless　linked　together　in　some　way

and　seemed　not　to　exist　when　gallic　acid　was　used；

for　ink　so　made　was　found　to　precipitate　only　after

a　long　exposure；　it　required　no　free　acid　to　keep　the

precipitate　in　solution；　and　retained　the　indigo　blue

color　for　a　long　time；　alkalis　did　not　decompose　the

ink；　and　provided　blacker　and　more　permanent　writing。

Determination　of　the　correct　proportions　of

gallic　acid　and　ferrous…sulphate　was　the　subject　of　prolonged

experiments　conducted　on　similar　lines　to　those

already　detailed。　The　conclusions　as　to　precipitation

were　also　similar。　Thirty　parts　of　iron　（150　of　ferrous…

sulphate）　and　100　parts　of　gallic　acid　were　found　to

be　the　most　suitable　proportions　for　ink…making。　It

is　advisable；　however；　not　to　discard　tannin　altogether；

owing　to　the　slow　blackening　of　the　gallic　acid　ink；

and　a　little　tannin　gives　initial　blackening　and　body；

while　it　is　absolutely　necessary　for　copying　ink。

Initial　blackness　can　also　be　ensured　by　oxidizing

21　per　cent　of　the　ferrous…sulphate　without　adding

the　extra　acid　necessary　to　the　formation　of　a　ferric

salt。



The　concluding　portion　of　his　research　is　devoted

to　the　influence　of　sugar　upon　the　permanence　of　ink；

and　the　results　of　the　experiments　are　summed　up　in

the　following　sentences：　〃It　would　be　injurious　to

add　3　per　cent　of　sugar　to　a　tan　in　ink；　while　from

4　to　10　per　cent　would　be　quite　allowable。　Most

copying　inks　contain　about　3。5　per　cent　of　sugar

not　far　from　the　critical　amount。　With　gallic　acid

more　than　3　per　cent　of　sugar　hardly　varies　the　precipitate；

but　the　importance　of　this　point　is　somewhat

diminished　by　the　fact　that　the　presence　of　sugar　is

by　no　means　necessary　in　a　writing　ink。　Dextrin　is

a　much　superior　substance　to　use。　Curiously　this

body　rapidly　precipitates　a　tannin　ink；　hence　it　is

useless　for　copying　ink；　but　for　the　gal