is that we are wont to imploy,
as the best) you pour a just quantity of Oyl of Tartar, and shake them well
together, you shall immediately see a notable Change of Colour, and the
Mixture will grow thick, and not transparent, but if you stay a while, till
the Grosser part be Precipitated to, and setled in the Bottom, you may
obtain a clear Liquor of a very lovely Colour, and exceeding delightfull to
the Eye. But, you must have a care to drop in a competent Quantity of Oyl
of Tartar, for else the Colour will not be so Deep, and Rich; and if
instead of this Oyl you imploy a clear _Lixivium_ of Pot-ashes, you may
have an Azure somewhat Lighter or Paler than, and therefore differing from,
the former. And if instead of either of these Liquors, you make use of
Spirit of Urine, or of Harts-horn, you may according to the Quantity and
Quality of the Spirit you pour in, obtain some further Variety (though
scarce considerable) of Caeruleous Liquors. And yet lately by the help of
this Urinous Spirit we made a Blew Liquor, which not a few Ingenious
Persons, and among them, some, whose Profession makes them very Conversant
with Colours, have looked upon with some wonder. But these Azure Colour'd
Liquors should be freed from the Subsiding matter, which the Salts of
Tartar or Urine precipitate out of them, rather by being Decanted, than by
Filtration. For by the latter of these ways we have sometimes found, the
Colour of them very much Impair'd, and little Superiour to that of the
grosser Substance, that it left in the Filtre.

_EXPERIMENT XXIII._

That Roses held over the Fume of Sulphur, may quickly by it be depriv'd of
their Colour, and have as much of their Leaves, as the Fume works upon,
burn'd pale, is an Experiment, that divers others have tried, as well as I.
But (_Pyrophilus_) it may seem somewhat strange to one that has never
consider'd the Compounded nature of Brimstone, That, whereas the Fume of
Sulphur will, as we have said, Whiten the Leaves of Roses; That Liquor,
which is commonly call'd Oyl of Sulphur _per Campanam_, because it is
suppos'd to be made by the Condensation of these Fumes in Glasses shap't
like Bells, into a Liquor, does powerfully heighten the Tincture of Red
Roses, and make it more Red and Vivid, as we have easily tried by putting
some Red-Rose Leaves, that had been long dried, (and so had lost much of
their Colour) into a Vial of fair Water. For a while after the Affusion of
a convenient Quantity of the L