INK. 
of them was equal to the gall-nut in this re- 
spect. 
Other salts of iron were also substituted 
to the sulphate. The muriate and nitrate 
of iron nearly equalled the sulphate in co- 
lour, but proved too corrosive to the paper, 
and as they were in no respect preferable 
to the sulphate, there is no reason for aban- 
doning it. 
Imagining that there must be some ex- 
cess of sulphuric acid in common ink, to 
which the fading might be imputed, Dr. 
Lewis tried to neutralize it by lime and 
alkalies, but with manifest injury, the colour 
being rendered thereby extremely fugitive. 
Another ingenious idea for avoiding the 
supposed excess of acid, was to separate 
the black atraraentous precipitate, wash it, 
and again diffuse it with water thickened 
with gum. This, indeed, makes a very 
good ink, but with the capital defect of not 
remaining so long suspended in the liquor, 
and especially of not fixing itself to the 
paper like common ink, but rather only 
slightly adhering like a weak gum varnish, 
and was readily washed off by water. 
Hence it appears that the acid of the salt of 
iron acts as a kind of mordant or inter- 
mede, between the atrementous precipitate 
and the paper, and causes a degree of che- 
mical union between them ; a real advan- 
tage which this species of ink possesses over 
all the lamp-black, or China inks, which, 
indeed, are rather black varnishes. 
With regard to the gummy ingredient, 
the effect of which is rather mechanical, 
it was found that any other gum-mucilage 
would answer as well ; but not glue, isin- 
glass, nor animal jelly of any kind. Be- 
sides, as these latter putrify by keeping, 
this alone would be a strong objection. 
Sugar is sometimes added to ink. It 
makes it flow somewhat easier from the 
pen, and gives it when dry a gloss which is 
admired by some. It has this quality, how- 
ever, of making it very slow in drying, 
which in most cases is an inconvenience. 
On account of the great improvements 
to the black atramentous dye produced by 
adding sulphate of copper, some have re- 
commended this addition to common ink, 
which is composed of the same materials ; 
but it does not appear that the same advan- 
tage is here obtained, and Dr. Lewis thinks 
it an useless addition. 
From the above observations, Dr. Lewis 
gives the following receipt for the composi- 
tion of ink: put into a stone or glass bottle, 
or any other vessel, three ounces of finely 
powdered galls, one ounce of green vitriol, 
one ounce of logwood finely rasped Or 
bruised, one ounce of gum-arabic, and a 
quart of soft water : shake the bottle well, 
and let the ingredients stand in a moder- 
ately warm place for a week or ten days, 
shaking it frequently in the day. It is then 
fit for use ; but a little before it is put into 
the ink-stand, it is better to shake the bot- 
tle that the colour may be- more uniformly 
diffused. 
To prevent the ink from moulding, Hoff- 
man recommends half a dozen cloves to be 
bruised with the gum arabic, and put into 
the bottle. This appears a useful addition. 
Instead of water alone, where a very fine 
ink is wanted, white wine, or vinegar and 
water, may be used. 
If the ink be wanted for use in a very 
short, time, the galls and logwood may be 
boiled for half an hour in the water, adding 
a little more to supply the waste, and the 
decoction while hot strained off through a 
cloth, and the gum arabic and cloves, and 
the sulphate of iron, both in fine powder, 
added to the decoction when in the bottle 
and shaken. The ink will then be fit for 
use almost immediately after the latter in- 
gredients are dissolved. It will be improv- 
ed by adding to the bottle some pieces of 
gall-nut coarsely bruised. Ink kept in a 
close bottle is always rather pale ; but it 
blackens by exposure to air in a few hours ; 
and probably in this way the colour is some- 
what more durable than if it were brought 
by previous exposure to its full colour at 
once. 
It has been mentioned that sugar ren- 
ders ink slow in drying. Advantage is in- 
geniously taken of this property in enabling 
it to give one,, and sometimes two impres- 
sions on soft paper, when strongly pressed. 
In this simple way letters are copied in 
merchant’s counting-houses, and offices of 
business. A little sugar is mixed with the 
ink, the writing-sheet is laid on the copy- 
ing press, a blank sheet of porous and 
damped paper is put over it, and by the 
pressure of the machine a perfect fac-simile 
of the writing is struck off, sufficiently le- 
gible for all purposes. 
This ingenious method saves a vast quan- 
tity of labour usually bestowed in copying 
letters, and besides prevents all possibility 
of mistakes. 
Sometimes the ink of very old writings is 
so much faded by time as to be illegible. 
Dr. Blagden, (Philosophical Transactions, 
vol. lxxvii.) in his experiments on this sub- 
01 q 2 
mm 
