the Antimony dissolv’d, as was lately mention’d, with the Acid Oyl of Vitriol; and though common Sulphur yields a White Precipitate, which the Chymists call Lac Sulphuris, yet I suppos’d the Precipitated Antimony would be of a deep Yellow Colour, as well, if made with Oyl of Vitriol, as if made only by Refrigeration and length of Time.  From this ’twas easie to deduce this Experiment, that if you put into one Glass some of the freshly Impregnated and Filtrated Solution of Antimony, and into another some of the Orange-Colour’d Mixture, (which I formerly shew’d you how to make with a Mercurial Solution and Oyl of Tartar) a few drops of Oyl of Vitriol dropp’d into the last mention’d Glass, would, as I told you before, turn the Deep Yellow mixture into a Cleer Liquor; whereas a little of the same Oyl dropp’d out of the same Viol into the other Glass would presently (but not without some ill sent) turn the moderately cleer Solution into a Deep Yellow Substance, But this, as I Said, succeeds not well, unless you employ a Lixivium that has but newly dissolv’d Antimony, and has not yet let it fall.  But yet in Summer time, if your Lixivium have been duly Impregnated and well Filtred after it is quite cold, it will for some dayes (perhaps much longer than I had occasion to try) retain Antimony enough to exhibit, upon the Affusion of the Corrosive Oyl, as much of a good Yellow Substance as is necessary to satisfie the Beholders of the Possibility of the Experiment.

Reflections upon the XL.  Experiment Compared with the X. and XX.

The Knowledge of the Distinction of Salts which we have propos’d, whereby they are discriminated into Acid, Volatile, or Salfuginous (if I may for Distinction sake so call the Fugitive Salts of Animal Substances) and fix’d or Alcalizate, may possibly (by that little part which we have already deliver’d, of what we could say of its Applicableness) appear of so much Use in Natural Philosophy (especially in the Practick part of it) that I doubt not but it will be no Unwelcome Corollary of the Preceding Experiment, if by the help of it I teach you to distinguish, which of those Salts is Predominant in Chymical Liquors, as well as whether any of them be so or not.  For though in our Notes upon the X. and XX.  Experiments I have shown you a way by means of the Tincture of Lignum Nephriticum, or of Syrrup of Violets, to discover whether a propounded Salt be Acid or not, yet you can thereby only find in general that such and such Salts belong not to the Tribe of Acids, but cannot determine whether they belong to the Tribe of Urinous Salts (under which for distinction sake I comprehend all those Volatile Salts of Animal or other Substances that are contrary to Acids) or to that of Alcalies.  For as well the one as the other of these Salino-Sulphurous Salts will restore the Caeruleous Colour to the Tincture of Lignum Nephriticum, and turn that of Syrrup of Violets into Green.