from Subsiding, which else it would in a short time do, though when 'tis subsided it will retain its Colour, and also be capable of being depriv'd of it by the Oyl newly mention'd. Thirdly, That if any Yellow matter stick at the sides of the Glass, 'tis but inclining the Glass, till the clarify'd Liquor can wash alongst it, and the Liquor will presently imbibe it, and deprive it of its Colour. Many have somewhat wondred, how I came to light upon this Experiment, but the Notions or Conjectures I have about the differing Natures of the Several Tribes of Salts, having led me to devise the Experiment, it will not be difficult for me to give you the Chymical Reason, if I may so speak, of the _Phænomenon_. Having then observ'd, that _Mercury_ being dissolv'd in Some _Menstruums_, would yield a dark Yellow Precipitate, and supposing that, as to this, common Water, and the Salts that stick to the _Mercury_ would be equivalent to those Acid _Menstruums_, which work upon the _Quick-silver_, upon the account of their Saline particles, I substituted a Solution of Sublimate in fair Water, instead of a Solution of _Mercury_ in _Aqua-fortis_, or Spirit of _Nitre_, that simple Solution being both clearer and free from that very offensive Smell, which accompanies the Solutions of _Mercury_ made with those other corrosive Liquors; then I consider'd, that That, which makes the Yellow Colour, is indeed but a Precipitate made by the means of the Oyl of Tartar, which we drop in, and which, as _Chymists_ know, does generally precipitate Metalline Bodies corroded by Acid Salts; so that the Colour in our case results from the Coalition of the Mercurial particles with the Saline ones, wherewith they were formerly associated, and with the Alcalizate particles of the Salt of Tartar that swim up and down in the Oyl. Wherefore considering also, that very many of the effects of Lixiviate Liquors, upon the Solutions of other Bodies, may be destroy'd by Acid _Menstruums_, as I elsewhere more particularly declare, I concluded, that if I chose a very potently Acid Liquor, which by its Incisive power might undo the work of the Oyl of Tartar, and disperse again those Particles, which the other had by Precipitation associated, into such minute Corpuscles as were before singly Inconspicuous, they would become Inconspicuous again, and consequently leave the Liquor as Colourless as before the Precipitation was made.