_Rusty_ Iron emits Gass, that is heavier than common Air, and therefore is improper. [Sidenote: 16 Bottles of Vitriol.] At the same Time, 16 Bottles of concentrated vitriolic Acid, or as it is improperly called Oil of Vitriol, were brought in their Packages near the Place, to be ready for Use: each Bottle at an Average containing 112 Pounds Averdupoise, of Vitriol: each full Bottle and Package together weighing from 136 to 148 Pounds. [Sidenote: 4 Pints of Water to a Pound Averdupoise of Acid.] 339. 2. To the Iron in each Vessel, was then poured a Quantity of Water, which was measured in the Proportion of about 4 to 1: i.e. 4 _Pints_ of Water to one _Pound_, of the vitriolic Acid. The Height of Water and Iron in each Vessel, being then gaged, was about 14 Inches. In a Line with the two smaller Vessels, and between them, was fixed another wooden Vessel or Cistern, filled with Water. [Sidenote: Improvements suggested.] (N. B. Fresh Water ought to have flowed continually into it, and to have run over the Top of the Cistern: for the same Quantity being once saturated, can no longer absorb the alcaline and fixed Air to be separated from the Gass before the latter enters the Balloon.) In the Cistern was fixed a Stage, consisting of 4 long Feet, (reaching to the Bottom of the Cistern,) nailed at their upper Ends to the Inside of an inverted Tub or Funnel, so placed over the Center of the Cistern, that 3 Inches of the lower Part of the Rim of the Funnel were under the Surface of the Cistern-Water: the Funnel was _cylindric_, 3 Feet across, and 2 Feet high. An Open was cut, 1 Foot Diameter, in the Bottom of the inverted Funnel: on the Circumference of which was nailed a Tin-Cylinder or common Conductor, 2 Feet high: and at a _certain_ Angle, as most convenient, was soldered a cylindric Arm, of equal Diameter, and 1 Foot long; having a Lip, Ring or Rim, on its outward circular Edge. Round this Rim was fastened a varnished Linen Tube, of equal Diameter with the Cylinder. At a small Distance, about a Yard from the Cistern, stood a slender Stillage, 3 Feet high; on which was supported a detached Tin-Cylinder or Connecter, 1 Foot long and 1 Foot Diameter, made with a Rim at each End: in the Center of whose lower Side was soldered, at right Angles, another Tin-Cylinder or Evacuatory, 6 Inches long and 6 wide: its Use is to let out any Water, that the Heat of the Mixture might cause to boil and rise up out of the fermenting Vessels: and thus be _evacuated_, without entering the Balloon: or, if condensed in the Balloon, might run out by the same Orifice. The opposite End of the varnished Linen Tube was fastened round one End of the detached Cylinder on the Stillage: and round the other, was tyed the Neck or Bottom-Opening of the Balloon.