6<2 I N K. 
ing or colouring leather and linen or woollen cloth ; re¬ 
ftoring inks that had been decayed by time; together with 
many methods of effacing writing, reftoring decayed pa¬ 
per, and different modes of fecret writing. The fifth 
treats of writing-inks made in different countries from 
gums, woods, the juices of plants, See. as well as of dif¬ 
ferent kinds of varnifhes. The lixth treats of the differ¬ 
ent methods of extracting vitriol, and the chemical ufes 
of it. 
Weckerus de Secretis, a treatife printed at Bafil in 1612, 
contains a number of curious particulars concerning ink. 
He gives alfo receipts for making gold and filver inks, 
compofed both with thefe metals and without them ; di¬ 
rections for making inks for fecret writing, and for de¬ 
facing them ; though in this laft part there are many par¬ 
ticulars bordering too much on the marvellous. 
In the year 1787, Dr. Blagden gave fome account of a 
method of reftoring decayed inks fo as to render them 
legible. His experiments originated from a converfation 
with Mr. Aftle, already quoted, on the queftion whether 
the inks made eight or ten centuries ago, and which are 
found to have preferved their colour very well, were made 
of the fame materials now employed or not? In order to 
decide the queltion, Mr. Aftle furnilhed the doCtor with 
feveral manuferipts on parchment and vellum front the 
9th to the 15th centuries inclufively. Some of thefe were 
Hill very black ; others of different fliades, from a deep 
yellowilh brown to a very pale yellow, in fome parts fo 
faint that it could fcarcely be feen. This was tried with 
iimple and phlogifticated alkalies, the mineral acids, and 
infufion of galls. From thefe experiments it appeared 
that the ink anciently employed was of the fame nature 
as at prefent; the letters turned of a reddifh or yellowilh 
brown with alkalies became pale, and were at length ob¬ 
literated by the dilute mineral acids. The drop of acid 
liquor, which had been put upon a letter, changed to a 
deep blue or green on the addition of phlogifticated al¬ 
kalies; with an infufion of galls, in fome cafes the letters 
acquired a deep tinge, in others a flight one. “ Hence 
(fays the doCtor) it is evident, that one of the ingredients 
-was iron, which there is no reafon to doubt was joined 
with the vitriolic acid ; and the colour of the more per¬ 
fect manuferipts, which in fome was a deep black, and in 
others a purplilh black, together with the reftitution of 
that colour in thofe which had loft it by the infufion of 
galls, fufficiently proved that another of the ingredients 
was aftringent matter, which from hiftory appears to have 
been that of galls. No trace of a black pigment of any 
fort was difeovered ; the drop of acid, which had com¬ 
pletely extracted a letter, appearing of an uniform pale 
and ferruginous colour, without an atom of black pow¬ 
der, or other extraneous matter, floating in it.” 
As this account differs very materially from the former 
extracted from Mr. Aftle’s writings, fo the reafon given 
for the continuance of. the colour differs no lefs. This, 
according to Dr. Blagden, “ feems to depend very much 
on a better preparation of the material upon which the 
writing was made, namely the parchment or vellum ; the 
blacked letters being generally thofe which had funk into 
It the deepeft. Some degree of erfervefcence was com¬ 
monly to be perceived when acids were in contact with 
the furface of thefe old vellums. I was led, however, to 
fufpeCt, that the ancient inks contained rather a lefs pro¬ 
portion of iron than the more modern ; for, in general, 
the tinge of colour produced by the phlogifticated alkali in 
the acid laid upon them, feemed left deep ; which, how¬ 
ever, might depend in part upon the length of time they 
have been kept ; and perhaps more gum was ufed in 
them, or they were walked over with fome kind of varnilh, 
though not fuch as gave any glofs. 
Among the fpecimens with which our author was fa¬ 
voured by Mr. Aftle, there was one which differed very 
materially from the reft. It was faid to be a manufeript 
©f the fifteenth century ; the letters were of a full engrof- 
fmg hand, angular, -without any hue ftrokes, broad, and 
very black. None of the chemical folvents above-merr- 
tioned feemed to produce any effect upon it. Moft of 
them feemed rather to make the letters blacker, probably 
by cleaning the furface; and the acids, after having been 
rubbed ftrongly upon the letters, did not ftrike any deeper 
tinge with the phlogifticated alkali. Nothing could ob¬ 
literate thefe but what took off part of the vellum; when 
fmall rolls of a dirty matter where to be perceived. “It 
is therefore unqueftionable (fays the doCtor) that no iron 
was ufed in this ink; and, from its refiftance to the che¬ 
mical folvents, as well as a certain clotted appearance in 
the letters when examined clolely, and in fome places a 
flight degree of glofs, I have little doubt that they were 
formed of a footy or carbonaceous powder and oil, proba¬ 
bly fomething like our prefent printers’ ink; and am not 
without fufpicion that they w'ere actually printed.” On 
examining this manufeript more fully, our author was 
convinced that it was really a part of a very ancient 
printed book. 
In confidering the methods of reftoring the legibility 
of decayed writings, our author obferves, that perhaps 
one of the belt may be to join phlogifticated alkali with 
the calx of iron which remains ; becaufe the precipitate 
formed by thefe two fubftances greatly exceeds that of 
the iron alone. On this fubjeft Dr. Blagden difagrees 
with Mr. Bergmann ; but, to bring the matter to a teft, 
the following experiments were made. 
1. The phlogifticated alkali was rubbed in different 
quantities upon the bare writing. This, in general, pro¬ 
duced little effect; though, in a few inftances, it gave a 
bluilh tinge to the letters, and increafed their intenlity; 
“ probably (fays the doCtor) where fomething of an acid 
nature had contributed to the diminution of their colour.” 
2. By adding, beiides the alkali, a dilute mineral acid to 
the writing, our author found his expectations fully an- 
fw-ered; the letters then changing quickly to a very deep 
and beautiful blue. It is but of little confequence whe¬ 
ther the acid or phlogifticated alkali be firft added; though 
upon farther confideration, the doctor inclined to begin 
with the alkali. The reafon is, that when the alkali is 
firft put on, the colour feems to fpread lefs, and thus not 
to hurt the legibility of the writing fo much as w'ould 
otherwife be done. His method is to fpread the alkali 
thin over the writing with a feather, then to touch it as 
gently as poflible upon or nearly over the letters with the 
diluted acid by means of a feather or bit of ftick cut to a 
blunt point. The moment that the acid liquor is ap¬ 
plied, the letters turn to a fine blue, beyond comparifon. 
ftronger than the original trace of the letter ; and by ap¬ 
plying a bit of blotting-paper to fuck up the l’uperfluous 
liquid, we may in a great meafure avoid ftaining the 
parchment; for it is this fuperfluous liquor, which, 
abforbing part of the colouring matter from the letters, 
becomes a dye to whatever it touches. Care ought, how¬ 
ever, to be taken not to allow the blotting-paper to come 
in contaCt with the letters, becaufe the colouring matter 
may eafily be rubbed off while foft and wet. And one of 
the three mineral acids will anfvver the purpofe effectu¬ 
ally. Dr. Blagden commonly ufed the marine. But which¬ 
ever of the three is ufed, it ought to be diluted fo far as 
not to be in danger of corroding the parchment; after 
which the degree of ftrength feems not to be a matter of 
great nicety. 
Another method of reftoring the legibility of old writ f 
ings is by wetting them with an infufion of galls in white 
wine; but this is fubjeCt to the fame inconvenience with 
the former, and is befides lefs efficacious. The doCfor is 
of opinion that the acid of the galls by itfelf would be 
better for the purpofe than the infufion of the whole fub- 
ftance of them; and lie thinks alfo that a preferable kind 
of phlogifticated alkali might be prepared either by puri¬ 
fying the common kind from iron as much as poflible, or 
by making ufe of the volatile alkali inftead of the fixed- 
See the Phil. Tranf. for 1787. 
A method has been propofed of preventing ink from 
3 decaying 
