Ether, or dulcified spirit of vitriol, is a very subtle penetrating fluid, prepared by distilling equal proportions of rectified spirit of wine, and vitriolic acid.

This spirit is the lightest, most volatile, and most inflammable yet known ; it floats on the surface of the most highly rectified spirit of wine, as oil floats on water: and, if it be dropped on a warm hand, it exhales immediately, dilfusing a penetrating fragrance, and leaving no trace of any moisture.

Ether is often successfully employed in medicine. It sometimes affords immediate relief in violent head-achs, by being externally applied to the painful part ; and suppresses the tooth-ach, when laid on the affected jaw. It has also been given internally, with considerable success, in hooping-coughs; in hysterical cases ; in asthma ; and, indeed, in almost every spasmodic affection, from a few drops, to the quantity of half an ounce, taken in a glass of cold water, which should be expeditiously swallowed, to prevent the exhalation of this volatile liquor.

There is another preparation of a similar nature, but more powerful in its effects, Called naphtha aceti, or acetous ether, which is seldom kept in the shops of this country. Its flavour is more pleasant than that of the former, being prepared by mixing 6 ounces of concentrated vitriolic acid with 10 ounces of rectified spirit of wine, and pouring this mixture gradually on 16 ounces'of regenerated tartar, in a glass retort; and then drawing off about te ounces, over a very mo-derate fire. This affords an excel-lent, but expensive, remedy in all the cases where the vitriolic ether is generally used.