Ribband betwixt the almost setting Sun and my Eye, not to mention the
Trials I have made to the same purpose, with other Bodies.

_EXPERIMENT XX._

Take good Syrrup of Violets, Imprægnated with the Tincture of the flowers,
drop a little of it upon a White Paper (for by that means the Change of
Colour will be more conspicuous, and the Experiment may be practis'd in
smaller Quantities) and on this Liquor let fall two or three drops of
Spirit either of Salt or Vinegar, or almost any other eminently Acid
Liquor, and upon the Mixture of these you shall find the Syrrup immediatly
turn'd Red, and the way of Effecting such a Change has not been unknown to
divers Persons who have produc'd the like, by Spirit of Vitriol, or juice
of Limmons, but have Groundlessly ascrib'd the Effect to some Peculiar
Quality of those two Liquors, whereas, (as we have already intimated)
almost any Acid Salt will turn Syrrup of Violets Red. But to improve the
Experiment, let me add what has not (that I know of) been hitherto
observ'd, and has, when we first shew'd it them, appear'd something
strange, even to those that have been inquisitive into the Nature of
Colours; namely, that if instead of Spirit of Salt, or that of Vinegar, you
drop upon the Syrrup of Violets a little Oyl of Tartar _per Deliquium_, or
the like quantity of Solution of Potashes, and rubb them together with your
finger, you shall find the Blew Colour of the Syrrup turn'd in a moment
into a perfect Green, and the like may be perform'd by divers other
Liquors, as we may have occasion elsewhere to Inform you.

_Annotation upon the twentieth Experiment_.

The use of what we lately deliver'd concerning the way of turning Syrrup of
Violets, Red or Green, may be this; That, though it be a far more common