WRITING INK. 
3 
luuscovaila sugar ; let these be all dissolved and well mixed by 
stirring. 
I do not cons'der a calcination of the sulphate of iron, Tin- suIpbaG- 
which Chaptal, Froust, and some others, have recommended, 
as of much importance ; for though the ink may be theieby 
inada to attain its degree of blackness, almost i.»in edi- 
ately, the strong disposition which iitk has to absorb oxigen 
from the atmosphere, until saturated therewith, will enable it, 
witliout such calcination, to attain an equal degree of blackness 
in a day or two, according to the temperature of the air, if the 
latter be allowed free access to it. I have omitted the sulphate 
of copper, for the reasons lately mentioned ; and if any portion 
of that metal were deemed beneticial, 1 should prefer verdi- 
grise to the sulphate, the latter containing a much larger pro- 
portion of acid, <lian even the sulphate of iron, and being, 
therefore, more likely to render the ink corrosive. 
Some persons hive recommended the addition of indigo to in,iij»o is not 
ink ; but unless it be previously dissolved by sulphuric acid, it advisable, 
will be found to subside, even though very finely powdered ; 
and, if so dissolved, this increased portion of acid will render 
the ink much more corrosive ; and after all, the blue atfordeJ 
by this combination (as was formerly noticed in regard to the 
sulphate of indigo) will not prove very durable, 
Gutn is highly useful to retard the separation and subsidence 
of its black part, or compound of colouring matter and iron, 
previous to its application to p.iper, as well as to hinder it from 
spreading and penetrating too far into the latter, when applied 
to it. 
As the acid part of galls is extracted more readily than the Co),] infusion 
other soluble parts, especially when the water employed for rrjtcitd. 
that purpose is cold, and as ink, which, along with colouring 
matter, contains more than the ordinary proportion of this acid, 
is the least disposed to produce a sedimen’: (for the reasons 
lately assigned) some persons have recommended the making 
of it by a cold infusion of galls. But when this is done, the 
galls must be employed in a much greater proportion j and even 
with this additional expence, there will be cause to fear, that 
£ 2 ink. 
