Repeated Experience has confirmed the Efficacy of this Medicine in all the Diseases before mentioned; and from the Consideration of it's uncommon Qualities, it may be presumed to be an excellent Remedy in many others, if judiciously given: Hence it seems surprising that so valuable an Addition, to the _Materia Medica_ as the AETHER doubtless is, should have been so much neglected, or so little known; but the Reasons are, that the Process whereby it was made was kept secret by some who rated the Preparation at a very extravagant Price, and not sufficiently attended to by others, who consider'd it only as a Chemical Curiosity, not as a Medicine. The chief Merit the Publisher of this Account pretends to, is, _the ascertaining the Medicinal Virtues of this curious Preparation_, by several Years Experience, and making them more publickly known; _the reducing it's Price_, which has hitherto been so extravagant that had it's Virtues and Properties been known, only a small number of the afflicted could have enjoy'd the Benefit of it; and, _the bringing it to a greater Degree of Perfection than any hitherto sold_; what he offers being a perfectly rectified Vitriolic AETHER. It may not be improper to give the Marks by which good AETHER may be known. It is perfectly colourless, except it has receiv'd some accidental Tinge from the Cork of the Phial in which it has been kept; and so volatile as to strike the Nose very powerfully. It's Smell is more or less sulphureous, according to the management of some Part of the Process. Wetting the Finger with it, or dropping a little upon the Hand, it vanishes instantly, and leaves no Moisture behind; so that the Part scarcely seems to have been wet. Half a Dozen Drops, dropped together upon a Table will disappear in a few Seconds of a Minute, and leave only the Appearance of a large oily Ring behind; but if it leaves the least Watery or Spirituous Moisture, or does not evaporate in much less than a Minute, it is not good. The best AETHER will dissolve in, or mix with, a certain Quantity of Water; and that is the best which requires the largest Quantity of Water to dissolve it: If, therefore, to fix Tea Spoonsful of Water in a small Phial, you add one of the AETHER to be examined, cork up the Phial, and shake them very well together, and upon standing a little while some part of the AETHER appears at Top, in form of Oil, sufficient to cover the surface of the Mixture, it may be pronounced good (provided it also answers, in the other Methods of Trial) and the more appears the better is the AETHER; but if none appears, or not enough to cover the surface of the Mixture, it was either adulterated, or not well rectified. If to this Mixture of AETHER and Water you add a little _Salt of Tartar_, and any Fermentation ensues, the AETHER was not well rectified. Upon shaking briskly a Phial containing AETHER, if the Bubbles, or Proof as they are usually called, do not disappear in less Time, and in larger