With an APPENDIX;
In which is an Account of some farther considerable Improvements made in the Method of procuring Plenty of Fresh-Water at Sea, viz. three Parts in four more than in the common Methods of Distilling: Also a farther Account of more Instances and Proofs of the good Effect of Ventilators in Ships: As also of the curing, in a few Minutes, the ill Taste of Turnip Milk, and of musty Liquors. Also, with great Ease, presently to make Cream or Milk Sillabubs, viz. by blowing Showers of Air up through them.
LONDON:
Printed for Richard Manby, in the Old-Bailey,
near Ludgate-Hill. M.DCC.LVI.
AN
ACCOUNT
OF THE
Great Benefit of blowing Showers of Fresh Air up thro’ Distilling Liquors.
1. The great Importance of having a sufficient Supply of fresh Water in Ships, has been the Occasion of many laudable Attempts to make Sea-water fresh and wholsome; but all the Attempts and Discoveries hitherto made, have laboured under this great and material Objection, viz. the great Quantity of Fuel that was necessary to distill, with a slow Progress, a small Quantity of Water, by any Methods of Distillation hitherto known. But I have lately happily, most unexpectedly, discovered an easy and effectual Method to distill great Quantities of Water with little Fuel; which I was led to by the following Incidents, viz. Mr. Shipley, Secretary of our Society, for the Encouragement of Arts, Manufactures and Commerce, brought me acquainted with Mr. William Baily of Salisbury-Court, the Author of many ingenious Contrivances; who shewed me, in a small Model of a Tin Vessel, a Method, by which he has happily increased the Force of the Engine to raise Water by Fire, viz. by lifting up some of the boiling Water, at every Stroke, by means of a conical Vessel, with small Holes in it, full of Tow; whereby the Quantity of the ascending Steam or Wreak was considerably increased. This led me to think, that a greater Quantity of Liquor might also by this Means be distilled; but on Trial I found the Increase to be only one twelfth Part, tho’ considerable in the expanded Form of a Steam. Hence I was led to try what would be the Effect of causing an incessant Shower of Air to ascend thro’ the boiling Liquor in a Still; and this, to my Surprise, I found on Trial to be very considerable. There was another Circumstance also, which probably conduced to lead my Mind to this Thought, viz. About six Months before, Mr. Littlewood, a Shipwright at Chatham, came thence purposely to communicate to me an ingenious Contrivance of his, soon to sweeten stinking Water, by blowing a Shower of fresh Air thro’ a Tin Pipe full of small Holes, layed at the Bottom of the Water. By this means, he told me, he had sweetened the stinking Bilge Water in the Well of some Ships; and also a But of stinking Water in an Hour, in the same manner as I blew Air up thro’ Corn and Gunpowder, as mentioned in the Book on Ventilators.
2. The Method, which I used to blow Showers of Air up thro’ the distilling Water, was by means of a flat round Tin Box, six Inches Diameter, and an Inch and half deep; which is placed at the Bottom of the Still, on four Knobs or Feet half Inch high, to make room for the Liquor to spread over the whole Bottom of the Still, that the Heat of the Fire may come at it. In larger Stills this Box must be proportionably larger, and have higher Feet. And whereas the Mouth of the Still is too narrow, for the Tin Box to enter, which Box ought to be within two Inches as wide as the Bottom of the Still; therefore the Box may be divided into two Parts, with a Hinge at one Edge or Side, and a Clasp at the other, to fix it together, when in the Still. This Box must be of Copper for distilling Sea-water; mine was made of Tin for other Liquors also. The Air-pipe, which passes thro’ the Head of the Still, will help to keep the Air-box from moving to and fro by the Motion of the Ship; or, if that should not be found sufficient, 3 or 4 small Struts may be fixed to the Sides of the Air-box. They must reach to the Sides of the Still. The Cover and Sides of the Air-box were punched full of very small Holes, one-fourth Inch distant from each other, and about the twentieth part of an Inch in Diameter. On the Middle of the Cover or Lid of this Air-box, was fixed a Nosil more than half Inch wide, which was fitted to receive, to put on, and take off the lower End of a Tin Pipe, which was twenty Inches long, and passed thro’ a Hole in the Head of the Still: four Inches of the upper end of this Pipe were bent to a Crook, almost at a right Angle to the upright Stem, in order thereby to unite the Crook to the widened Nose of a Pair of Kitchen double Bellows, by means of a short Leathern Pipe of Calves-skin. See Fig. 1st. This Tin Air-box, and many more of them for other Persons, were made by Mr. Tedway, Tinman, over-against the Meuse-Gate, Charing-Cross.
3. The double Bellows were bound fast to a Frame, at the upper Part of the Iron Nose, and at the lower Handle, in order the more commodiously to work them. And that the upper Half of the double Bellows may duly rise and fall, in order to cause a constant Stream of Air; (besides the usual contracting spiral Springs within side) several flat Weights of Lead must be layed on the upper Part of the Bellows, near the Handle, with a Hole in their Middle, to fix them on an upright Iron Pin fastened on the Bellows: That by this Means the Weights may the more commodiously be put on or taken off. For, according to the different Depths of the Liquor in the Still, so will the Force of the included Air, against the upper Board of the Bellows, be more or less. Thus, supposing the Depth of the Water in the Still to be twelve Inches; from the Surface of the depressed Water in the Air-Box; then the Pressure of the included Air against the upper Part of the Bellows, will be equal to that of a Body of Water a Foot deep, and as broad as the inner Surface of that Board. It will, therefore, be requisite, to add or take off Weights, according to the different Depths of the Water in the Still, at different Periods of the same Distillation. The Bellows must be proportionable to the Size of the Still, but need not be very large. Wherever the Stills are fixed in Ships, the Air may be conveyed to them from the Bellows, either thro’ a small leathern Pipe, distended with Spiral Coiles of Wyre, or thro’ Bamboo Canes, or broad small wooden Pipes, like hollow fishing Rods.
4. When I first distilled in this ventilating Way, in order to estimate, what the Difference might be in the Quantity distilled, by that or the common Method, I tried both Ways, by receiving the distilled Liquor into a Quarter of a Pint Glass, estimating the Times, by a Pendulum beating Seconds. Where I found, to my Surprise, that sometimes three times more was distilled by Ventilation than by the usual Way: But finding Inequalities in the small Quantities thus distilled, in order the more fully and assuredly to ascertain the true Proportion there was in the two Methods of distilling, I put three Gallons of Water into the Still; and, when it boiled, put on the Still-head, and fixed its Nose to the Worm-tub Pipe; which Tub was full of cold Water. When it had distilled for an Hour, the Receiver was instantly taken away. And on measuring the distilled Water, found it to be two Quarts and 45 cubick Inches by a Glass divided into cubick Inches. And a Gallon containing 282 cubick or solid Inches, this Quantity of distilled Water, which was 186 cubick Inches, is 1/1.5 th Part of a Gallon.
5. Then, filling the Still as full of Water as before, and when it began to boil, fixing the Head to the Still and Worm-tub, which was full of cold Water; there was distilled in an Hour, with constantly blowing Showers of fresh Air up thro’ the stilling Liquors, five Quarts, less by seven cubick Inches, which is 345.5ths cubick Inches; that is, little less than the double of the Quantity that is distilled in the usual Way. In several other Distillations of a Quart at a Time, I found the Quantity distilled by Ventilation, to be more than the double of that in the usual Way. So that the Quantity by Ventilation, may at a Medium be estimated the double of the usual Distillation. It is the well known Property of moving Air, to carry along with it a considerable Quantity of adjoining Vapour, as also of falling Water to carry much Air down along with it.