Wednesday, October 24, 2012

Desalination - An Historical Note

I ran across a 1791 report by Thomas Jefferson (as the Secretary of State) concerning a petition by one Jacob Isaacks of Newport, Rhode Island who was trying to sell his invention of obtaining fresh water from salt water to the U.S. Government to aid in all pursuits maritime.  All he wanted was " convey to the Government of the United States a faithful account of his art, or secret, to be used by or within the United States, on their giving him a reward suitable to the importance of the discovery, and, in the opinion of the Government, adequate to his expenses and the time he has devoted to the bringing it into effect."

Jefferson's report is a classic.  He begins by noting that Sir Francis Bacon had already observed "...that, with a heat sufficient for distillation, salt would not rise in vapor, and that salt water 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."  

Jefferson goes on to note that initially filtration and congelation were both tried - unsuccessfully.  So you're thinking there might be some hope for Mr. Isaacks.  He then notes that Sir Richard Hawkins in the 16th century, and Glauber, Hauton and Lister in the 17th century, and Hales, Appleby, Butler, Chapman, Hoffman and Dove in the 18th century had all been successful in producing fresh water from sea water - and with only common items normally found on virtually every ship on the high seas.

Jefferson notes that "With this apparatus of a pot, tea-kettle, and gun-barrel, the Dolphin, a twenty-gun 1761, from fifty-six gallons of sea water, and nine pounds of wood and sixty-nine pounds of pit-coal, made forty-two gallons of good fresh water, at a rate of eight gallons an hour."   He also notes the Dorsetshire's 19 quarts of pure water in four hours with 10 pounds of wood in 1769.  And the Slambal's 10 quarts from six gallons in 3 hours in 1773.  Finally mentioning Dr. Irvin and Dr. Franklin's experiments.

There were ultimately two killers for Mr. Isaacks.  First, Jefferson discovered that Dr. Irvin had actually obtained a premium of 5,000 pounds from the British parliament for advances in sea water distillation twenty years earlier in 1771, and, controlled experiments of Isaack's process - which included "a mixture, the composition of which he did not explain" actually yielded the same amount of fresh water, over a slightly longer period of time, but with slightly less fuel required.

Jefferson concluded that "On the whole, it was evident that Mr. Isaack's mixture produced no advantage, either in process or result of the distillation.".  He also wrote:  "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."

Out of all this research and experimentation, Jefferson discovered that far too few sailors were even aware of this potentially life-saving process, and as such, he recommended:  "Let the clearance for every vessel sailing from the ports of the United States be printed on paper, on the back whereof shall be a printed account of the essays which have been made for obtaining fresh from salt water, mentioning briefly those which were 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 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."

There you have it.  Don't try to fleece the U.S. Government on Thomas Jefferson's watch!  And I have to believe that given a few more years, he would have also been promoting such a process for all the less-than-pure groundwater sources, as well.  What a remarkable American!

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