WRITING INK. 
23 1 
ther ; that those of the broad-leaf ’d oak were lighter and less 
esteemed ; but that it moreover produces a sort of black galls,, 
which were more useful in dyeing j* and these he mentions 
again in the next chapter j and in the 4th chapter of his 20th 
book also ; where, after describing the different sorts of galls, 
he adds, that they all possess similar properties, and dye hair 
or wool Hack, ic Omnes capillos denigrant.” That their co- 
louring matter was combined with iron for this purpose, is not, 
so far as I can recollect, expressly stated any where, but that 
Pliny was acquainted with the colour produced by such combi- 
nation, is evident from the 11th chapter of his thirty-fourth 
book j in which, after mentioning th^ salt of copper (blue Galls a very 
vitriol) as being frequently adulterated by that of iron (green ancient test ’ 
vitriol, which the Greeks call chalcanthon ) he observes, that 
this adulteration might be detected by impregnating paper (that 
of the papyrus, with an infusion of gall nuts, and then smear- 
ing it over with a solution of the cuprous salt, which, if so 
adulterated, would produce a black colour. =>(“ Deprehenditur 
papyro galla prius macerato : nigrescit statim aerugine 
iilita.”) But the knowledge which the ancients possessed of 
the production of a black colour by a combination of iron 
with galls, oak bark, &c. is demonstrated by the use which 
they made of a solution of iron, to give that colour to tanned 
leather. This solution, or the sulphate of iron, dissolved by 
1 water for, that purpose, was generally called by the name of 
iC atramentum sutoriumf,” shoe-maker's black. The Greeks 
and Romans, indeed, had incorrect notions of the nature of 
the sulphate of iron, and supposed it to bear some relation to 
copper, as the moderns did long after; an error which occa- 
sioned it to be commonly called, as it is even at this time, cop- 
* “ Sed gallarn Hemeris optimam, & coriis perficiendis aptissimam ; 
ae similem huic lati folia, sed leviorera, irmltoque minus probatam ; fer£ 
, et nigram : duo, enim genere sunt : hcec tingendis utilior.'’ 
f This was afterwards used to signify bribery, and a person put 
f upon his trial, and corruptly acquitted, was said to be “ atramento 
: suturio absolntus,” absolved by shoe-maker’s black. 
peras „ 
