Experiments and Considerations Touching Colours (1664) by Robert Boyle
page 220 of 285 (77%)
page 220 of 285 (77%)
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which though they run _per Deliquium_, as readily as Salt of Tartar, belong
in other respects, not to the family of Alcaliz, much less to that of Salfuginous, or that of Acid Salts. Perhaps too, I may know a way of making a highly operative Saline Body that shall neither change the Colour of Syrrup of Violets, nor Precipitate the Solution of Sublimate; And, I can likewise if I please conceal by what Liquors I perform such changes of Colour, as I have been mentioning to you, by quite altering the Texture of some ordinary Chymical productions, the Exploration of which is the main use of the fortieth Experiment, which I think teaches not a little, if it teach us to discover the nature of those things (in reference to Salt) that are obtain'd by the ordinary Chymical Analysis of mix'd Bodyes, though perhaps there may be other Bodyes prepar'd by Chymistry which may have the same Effects in the change of Colours; and yet be produc'd not from what Chymists call the Resolution of Bodies, but from their Composition. But the discoursing of things of this nature is more proper for another place. I shall now onely add, what might perhaps have been more seasonably told you before; That the Reason why the way of Exploration of Salts hitherto deliver'd, succeeds in the Solution of Sublimate, depends upon the particular Texture of that Solution, as well as upon the differing Natures of the Saline Liquors imploy'd to Precipitate it. For Gold dissolv'd in _Aqua Regia_, whether you Precipitate it with Oyl of Tartar which is an Alcaly, or with Spirit of Urine, or Sal Armoniack which belongs to the family of Volatile Salts, will either way afford a Yellow substance: though with such an Acid Liquor, as, I say not Spirit of Salt, the Body that yields it, being upon the matter an Ingredient of _Aqua Regis_, but Oyl of Vitriol it self, I did not find that I could Precipitate the Metall out of the Solution, or destroy the Colour of it, though the same Oyl of Vitriol would readily Precipitate Silver dissolv'd in _Aqua-fortis_. And if you dissolve pure Silver in _Aqua-fortis_, and suffer it to shoot into Crystals, the cleer Solution of these made in fair Water, will afford a |
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