CHAPTERLXII.DEFECTS, IN THE COMPOSITION FOR BALLOONS, REMEDIED.ALSO ON THE COCHUC-VARNISH.Section 320.BALLOONS are defective in the Composition forthe Varnish; which, till lately, was incapable of rendering the Balloon completely anddurablyAir-tight.321. It was sometime ago reported at Paris, that Mr. Dutourny de Villiere had undertaken to construct a Balloon so trulyimpèrmeable, that he woud warrant the Duration of it, forseveral Weeksin the Air.And it issinceknown that thisDesideratumof the Art has been effected, in the Composition for the celebrated Balloon of Messrs. Auban and Vallet,firstmade subject to Direction.322. Mr. Berniard, a French Chymist, has made curious tho’ unsuccessful Experiments, in order to melt the cochuc or elastic Bottle; as may be seen in the 17th Volume of the “Journal de Physique.”Mr. Faujas and others made similar Trials.323. The Writer, unacquainted with what hadthenbeen done in this Matter, coud not help remarking the striking Properties of theCochucin its present Form, to answer every Intention of the best Varnish, if its Price was lower;—viz.compact,pliant,unadhesive, andunalterable by Weather;—if it coud be dissolved, and afterwards made to recover its presentunadhesiveForm: an Art in which the East and West-Indians are stillour Masters.He has, however, after expensive Trials and Combinations, been able to reduce it into alimpid Liquor.As it may prove a useful Ingredient forAir-tightVarnish; the Secret he now discovers to the World: and it is merely this.324. “Take any Quantity of the Cochuc, as two Ounces Averdupois: cut it into small Bits, with a Pair of Scissars.Put a strong Iron-Ladle (such as Plumbers or Glaziers melt theirLeadin) over a common Pit-Coal or other Fire.The Fire must be gentle, glowing, andwithoutSmoke.When the Ladle is hot, much below aredHeat; put a single Bit into the Ladle.IfblackSmoke issues, it will presentlyflame, and disappear: or it will evaporate without Flame: the Ladle isthentoo hot.When the Ladle is less hot, put in a second Bit, which will produce awhiteSmoke.ThiswhiteSmokewill continue during the Operation, and evaporate the Cochuc: therefore no Time is to be lost: but little Bits are to be put in, a few at a Time, till the whole are melted. It shoud be continually and gently stirred with an Iron or Brass Spoon.The Instant the Smoke changes fromwhitetoblack, take off the Ladle; or the whole will break out into a violent Flame, and be spoiled or lost.(Care must be taken thatno Waterbe added: a few Drops only of which, woud—on Account of its superiorspecific Gravity, for the Cochuc swims in Water—make it boil over furiously, with great Noise.)At this Period of the Process; two Pounds, or one Quart of thebest drying-oil, (or even ofrawLinseed-Oil, which, together with a few Drops of Neat’s-Foot-Oil, must have stood a Month, or not so long, on a Lump of Quick-Lime, to make it more or lessdrying)—being poured off the Lime-Lees; is to be put into themelted Cochuc, and stirred till hot: and the whole poured into a glazed Vessel, throu’ a coarse Gauze, or fine Sieve.When settled and clear, which will be in a few Minutes; it is fit for Use, either hot or cold.The Silk shoud be stretched all Ways horizontally, by Pins or Tenter-Hooks, on Frames; which Frames, the greater they are in Length, the better: and the Varnish poured oncold, inhotWeather; andhot, incoldWeather.It isperhapsbest, always to lay it on, whencold.The Art of laying it on properly, consists in makingno intestineMotion in the Varnish, which woud create minute Bubbles. Therefore Brushes of every Kind are improper.Each Bubble breaks in drying, and forms a small Hole, throu’ which theAirwilltranspire.
CHAPTERLXII.
Section 320.BALLOONS are defective in the Composition forthe Varnish; which, till lately, was incapable of rendering the Balloon completely anddurablyAir-tight.
321. It was sometime ago reported at Paris, that Mr. Dutourny de Villiere had undertaken to construct a Balloon so trulyimpèrmeable, that he woud warrant the Duration of it, forseveral Weeksin the Air.
And it issinceknown that thisDesideratumof the Art has been effected, in the Composition for the celebrated Balloon of Messrs. Auban and Vallet,firstmade subject to Direction.
322. Mr. Berniard, a French Chymist, has made curious tho’ unsuccessful Experiments, in order to melt the cochuc or elastic Bottle; as may be seen in the 17th Volume of the “Journal de Physique.”
Mr. Faujas and others made similar Trials.
323. The Writer, unacquainted with what hadthenbeen done in this Matter, coud not help remarking the striking Properties of theCochucin its present Form, to answer every Intention of the best Varnish, if its Price was lower;—viz.compact,pliant,unadhesive, andunalterable by Weather;—if it coud be dissolved, and afterwards made to recover its presentunadhesiveForm: an Art in which the East and West-Indians are stillour Masters.
He has, however, after expensive Trials and Combinations, been able to reduce it into alimpid Liquor.
As it may prove a useful Ingredient forAir-tightVarnish; the Secret he now discovers to the World: and it is merely this.
324. “Take any Quantity of the Cochuc, as two Ounces Averdupois: cut it into small Bits, with a Pair of Scissars.
Put a strong Iron-Ladle (such as Plumbers or Glaziers melt theirLeadin) over a common Pit-Coal or other Fire.
The Fire must be gentle, glowing, andwithoutSmoke.
When the Ladle is hot, much below aredHeat; put a single Bit into the Ladle.
IfblackSmoke issues, it will presentlyflame, and disappear: or it will evaporate without Flame: the Ladle isthentoo hot.
When the Ladle is less hot, put in a second Bit, which will produce awhiteSmoke.
ThiswhiteSmokewill continue during the Operation, and evaporate the Cochuc: therefore no Time is to be lost: but little Bits are to be put in, a few at a Time, till the whole are melted. It shoud be continually and gently stirred with an Iron or Brass Spoon.
The Instant the Smoke changes fromwhitetoblack, take off the Ladle; or the whole will break out into a violent Flame, and be spoiled or lost.
(Care must be taken thatno Waterbe added: a few Drops only of which, woud—on Account of its superiorspecific Gravity, for the Cochuc swims in Water—make it boil over furiously, with great Noise.)
At this Period of the Process; two Pounds, or one Quart of thebest drying-oil, (or even ofrawLinseed-Oil, which, together with a few Drops of Neat’s-Foot-Oil, must have stood a Month, or not so long, on a Lump of Quick-Lime, to make it more or lessdrying)—being poured off the Lime-Lees; is to be put into themelted Cochuc, and stirred till hot: and the whole poured into a glazed Vessel, throu’ a coarse Gauze, or fine Sieve.
When settled and clear, which will be in a few Minutes; it is fit for Use, either hot or cold.
The Silk shoud be stretched all Ways horizontally, by Pins or Tenter-Hooks, on Frames; which Frames, the greater they are in Length, the better: and the Varnish poured oncold, inhotWeather; andhot, incoldWeather.
It isperhapsbest, always to lay it on, whencold.
The Art of laying it on properly, consists in makingno intestineMotion in the Varnish, which woud create minute Bubbles. Therefore Brushes of every Kind are improper.
Each Bubble breaks in drying, and forms a small Hole, throu’ which theAirwilltranspire.