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Boyle, Robert, 1627-1691

"Experiments and Considerations Touching Colours (1664)"

And to this Observation of
our _Botanist_ we will add an Experiment of our own, (made before we met
with That) which, though in many Circumstances, very differing, serves to
prove the same thing; for having taken of the deeply Red Juice of
_Buckthorn_ Berries, which I bought of the Man that uses to sell it to the
Apothecaries, to make their Syrrup _de Spina Cervina_, I let some of it
drop upon a piece of White Paper, and having left it there for many hours,
till the Paper was grown dry again, I found what I was inclin'd to suspect,
namely, That this Juice was degenerated from a deep Red to a dirty kind of
Greyish Colour, which, in a great part of the stain'd Paper seem'd not to
have so much as an Eye of Red: Though a little Spirit of Salt or dissolv'd
_Alcaly_ would turn this unpleasant Colour (as formerly I told you it would
change the not yet alter'd Juice) into a Red or Green. And to satisfie my
self, that this Degeneration of Colour did not proceed from the Paper, I
drop'd some of the deep Red or Crimson Juice upon a White glaz'd Tile, and
suffering it to dry on there, I found that ev'n in that Body, on which it
could not Soak, and by which it could not be Wrought, it nevertheless lost
its Colour.


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