of so many branches of science, had observed, that with a heat sufficient for distillation, salt will not rise in vapor, and that saltwater distilled is fresh; and it would seem, that all mankind might have observed that the earth is supplied with fresh water chiefly by exhalation from the sea, which is, in fact, an insensible distillation effected by the heat of the sun; yet this, although the most obvious, was not the first idea in the essays for converting salt-water into fresh; filtration was tried in vain, and congelation could be resorted to only in the coldest regions and seasons. In all the earlier trials by distillation, some mixture was thought necessary to aid the operation by a partial precipitation of the salt, and other foreign matters contained in sea-water. Of this kind, were the methods of Sir Richard Hawkins in the sixteenth century, of Glauber, Hauton, and Lister, in the seventeenth, and of Hales, Appleby, Butler, Chapman, Hoffman, and Dore, in the eighteenth; nor was there anything in these methods worthy noting on the present occasion, except the very simple still contrived extempore by Captain Chapman, and made from such materials as are to be found on board every ship, great or small; this was a common pot, with a wooded lid of the usual form; in the centre of which a hole was bored to receive perpendicularly, a short wooden tube made with an inch-and-a-half auger, which perpendicular tube received at its top, and at an acute angle, another tube of wood also, which descended until it joined a third of pewter made by rolling up a dish and passing it obliquely through a cask of cold water; with this simple machine he obtained two quarts of fresh water an hour, and observed that the expense of fuel would be very trifling, if the still was contrived to stand on the fire along with the ship's boiler.

In 1762, Doctor Lind, proposing to make experiment of several different mixtures, first distilled rain-water, which he supposed would be the purest, and then sea-water, without any mixture, which he expected would be the least pure, in order to arrange between these two supposed extremes, the degree of merit of the several ingredients he meant to try; "to his great surprise," as he confesses, the sea-water distilled without any mixture, was

as pure as the rain-water; he pursued the discovery and established the fact, that a pure and potable fresh water may be ob tained from salt-water by simple distillation, without the aid of any mixture for fining or precipitating its foreign contents. In 1767, he proposed an extempore still, which, in fact, was Chapman's, only substituting a gun-barrel instead of Chapman's pewter tube, and the hand-pump of the ship to be cut in two obliquely and joined again at an acure angle, instead of Chapman's wooden tubes bored expressly; or instead of the wooden lid and upright tube, he proposed a tea-kettle (without its lid or handle) to be turned bottom upwards over the mouth of the pot by way of still-head, and a wooden tube leading from the spout to a gunbarrel passing through a cask of water, the whole luted with equal parts of chalk and meal moistened with salt-water. With this apparatus of a pot, tea-kettle, and gun-barrel, the Dolphin, a twenty-gun ship, in her voyage around the world in 1768, from 56 gallons of sea-water and with 9 lbs. of wood and 69 lbs. of pitcoal made 42 gallons of good fresh water, at the rate of 8 gallons an hour. The Dorsetshire, in her passage from Gibraltar to Mahon in 1769, made 19 quarts of pure water in four hours with 10 lbs. of wood, and the Slambal in 1773, between Bombay and Bengal, with the hand-pump, gun-barrel, and a pot of 6 gallons of sea-water, made ten quarts of fresh water in three hours.

In 1771, Dr. Irvin putting together Lind's idea of distilling without a mixture, Chapman's still, and Dr. Franklin's method of cooling by evaporation, obtained a premium of five thousand pounds from the British parliament. He wet his tube constantly with a mop instead of passing it through a cask of water; he enlarged its bore also, in order to give a free passage to the vapor, and thereby increase its quantity by lessening the resistance or pressure on the evaporating surface. This last improvement was his own; it doubtless contributed to the success of his process; and we may suppose the enlargement of the tube to be useful to that point at which the central parts of the vapor passing through it would begin to escape condensation. Lord Mulgrave used his method in his voyage towards the north pole in 1773, making

from 34 to 40 gallons of fresh water a day, without any great addition of fuel, as he says.

M. de Bougainville, in his voyage round the world, used very successfully a still which had been contrived in 1763 by Poyssonier to guard against the water being thrown over from the boiler into the pipe, by the agitation of the ship. In this, one singularity was, that the furnace or fire-box was in the middle of the boiler, so that the water surrounded it in contact. This still, however, was expensive, and occupied much room.

Such was the advances already made in the art of obtaining fresh from salt-water, when Mr. Isaacs, the petitioner, suggested his discovery. As the merit of this could be ascertained by experiment only, the Secretary of State asked the favor of Mr. Rittenhouse, President of the American Philosophical Society, of Dr. Wistar, professor of chemistry in the college at Philadelphia, and Dr. Hutchinson, professor of chemistry in the University of Pennsylvania, to be present at the experiments. Mr. Isaacs fixed the pot, a small caboose, with a tin cap and straight tube of tin passing obliquely through a cask of cold water; he made use of a mixture, the composition of which he did not explain, and from 24 pints of sea-water, taken up about three miles out of the Capes of Delaware, at flood-tide, he distilled 22 pints of fresh water in four hours with 20 lbs. of seasoned pine, which was a little wetted by having lain in the rain.

In a second experiment of the 21st of March, performed in a furnace, and five-gallon still at the college, from 32 pints of seawater he drew 31 pints of fresh water in 7 hours and 24 minutes, with 51 lbs. of hickory, which had been cut about six months. In order to decide whether Mr. Isaacs' mixture contributed in any and what degree to the success of the operation, it was thought proper to repeat his experiment under the same circumstances exactly, except the omission of the mixture. Accordingly, on the next day, the same quantity of sea-water was put into the same still, the same furnace was used, and fuel from the same parcel; it yielded, as his had done, 31 pints fresh water in 11 minutes more of time, and with 10 lbs. less of wood.

ment.

On the 24th of March, Mr. Isaacs performed a third experiFor this, a common iron pot of three and a half gallons was fixed in brick work, and the flue from the hearth wound once around this pot spirally, and then passed off up a chimney.

The cap was of tin, and a straight tin tube o about two inches diameter passing obliquely through a barrel of water, served instead of a worm. From sixteen pints of sea-water he drew off fifteen pints of fresh water, in two hours fifty-five minutes, with 3 lbs. of dry hickory and 8 lbs. of seasoned pine. This experiment was also repeated the next day, with the same apparatus, and fuel from the same parcel; but without the mixture, sixteen pints of sea-water yielded in like manner fifteen pints of fresh in one minute more of time, and with lb. less of wood. On the whole, it was evident that Mr. Isaacs' mixture produced no advantage either in the process or result of the distillation.

The distilled water in all these instances, was found on experiment to be as pure as the best pump water of the city; its taste, indeed, was not as agreeable, but it was not such as to produce any disgust. In fact, we drink, in common life, in many places, and under many circumstances, and almost always at sea, a worse tasted and probably a less wholesome water.

The obtaining fresh from salt-water was for ages considered as an important desideratum for the use of navigators. The process for doing this by simple distillation is so efficacious, the erecting an extempore still with such utensils as are found on board of every ship, is so practicable, as to authorize the assertion that this desideratum is satisfied to a very useful degree. But though this has been done for upwards of thirty years, though its reality has been established by the actual experience of several vessels which have had recourse to it, yet neither the fact nor the process is known to the mass of seamen, to whom it would be the most useful, and for whom it was principally wanted. The Secretary of State is therefore of opinion that since the subject has now been brought under observation, it should be

made the occasion of disseminating its knowledge generally and effectually among the seafaring citizens of the United States. The following is one of the many methods which might be proposed for doing this: Let the clearance for every vessel sailing from the ports of the United States be printed on a paper, in the back whereof shall be a printed account of the essays which have been made for obtaining fresh from salt-water, mentioning shortly those which have been unsuccessful, and more fully those which have succeeded, describing the methods which have been found to answer for constructing extempore stills of such implements as are generally on board of every vessel, with a recommendation in all cases where they shall have occasion to resort to this expedient for obtaining water, to publish the result of their trial in some gazette on their return to the United States, or to communicate it for publication to the office of the Secretary of State, in order that others may, by their success, be encouraged to make similar trials, and be benefited by any improvements or new ideas which may occur to them in practice.

II. Opinion on the proposition for establishing a Woollen Manufactory in Virginia.

The House of Delegates of Virginia seemed disposed to adventure £2,500 for the encouragement of this undertaking, but the Senate did not concur. By their returning to the subject, however, at a subsequent session, and wishing more specific propositions, it is probable they might be induced to concur, if they saw a certain provision that their money would not be paid for nothing. Some unsuccessful experiments heretofore may have suggested this caution.

Suppose the propositions brought into some such shape as this: The undertaker is to contribute £1,000, the State £2,500, viz.: the undertaker having laid out his £1,000 in the necessary im