[ 50 ] 
ginal blacknefs ; by which it appears, that it was 
the aftringent parts of thofe Inks which had 
failed. 
Does it not appear, by thefe experiments, that,, 
though lime-water tends to deepen the colour pro- 
duced by fome aftringents and martial vitriol,, it 
by no means adds to the duration of thofe colours;, 
and as lime-water, either by trituration or coclion, 
entirely deftroys the property, in logwood, ot 
linking black with martial vitriol, it can by no 
means be of fervice, in the black dye, where log- 
wood is a material ingredient. 
Does it not alfo appear, that a flight boiling is 
preferable to trituration, for the purpofes of dying, 
when a durable, colour is wanted ? 
Having obferved. a. folution of iron, in a vege- 
table acid, (truck a deeper black, upon mixture 
with an aftringent, and produced its effect much 
more expeditioufly, than a ftrong folution of mar- 
tial vitriol ; it occurred to me, that the iron, be- 
ing more flightly combined with the vegetable 
acid, than with the vitriolic, made it more £afy* 
for the aftringent matter to decompound the for- 
mer, and produce an ink;, if this was the cafe, I 
fufpefted, that lime-water deepened the colour of 
aftringent and chalybeate mixtures, not fo much 
by its action upon the aftringent, as upon the 
chalybeate, the lime uniting with the fuperabun- 
clant acid, and leaving the iron, with fo much of 
the acid, as. is neceflary for the formation of an 
ink, to be more eafily attached by the aftringent 
matter of the vegetable. 
But! 
