The First Patent

Henry M. Paynter
Being a revision of the article originally appearing in the magazine "Invention & Technology" primarily to benefit from David Maxey's recent discovery of the correct Samuel Hopkins [ Corrections are in underlined green and the original text is bracketed in red ]

In two hundred years of existence, the U.S. Patent Office has issued nearly five million patents, which together document the greatest industrial development in human experience.

How did it all start? To whom and for what was the first U.S. patent issued?

Samuel Hopkins, of Philadelphia, Pennsylvania [Pittsford, Vermont], received Patent No. 1 on July 31, 1790, for an improvement "in the making Pot ash and Pearl ash by a new Apparatus and Process." The patent was signed by President George Washington, Attorney General Edmund Randolph, and Secretary of State Thomas Jefferson. Only two other patents were granted that year, one for a new candle-making process and the other the flour-milling machinery of Oliver Evans.

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The first patent

Only after 1955 were the original documents for Hopkins' patent located, together with a detailed disclosure and licensing prospectus he published in 1791. These have helped reveal that the patent was important not only because it was the first of its kind but also because it was vitally linked the nation's early economy. In fact, potash was America's first industrial chemical.

Potash is an impure form of potassium carbonate, mixed with other potassium salts. Until the 1860s it was derived solely from the ashes of hardwood trees and certain other plants. (The name of the element potassium is derived from the word potash.)

Pearl ash is a less impure form of potassium carbonate. Its name comes from its pearly color. Potash was a leading industrial alkali from antiquity until the close of the nineteenth century, when it was finally abandoned for most uses in favor of soda (sodium carbonate). It was essential for making soap and glass, dyeing fabrics, baking, and making saltpeter for gunpowder. Today its principal use is in fertilizers.

By 1750 there was a steady international demand for potash soap, particularly in England, where "fulling sope" was much needed to wash wool before it was woven in the burgeoning mills. Having greatly depleted its own timber resources, the mother country sent experts and manuals on potash making to its American colonies and otherwise encouraged potash production with tariff incentives.

Around 1760 England needed several thousand tons of potash a year. Most of it came from Russia. To try to save money, British-capitalized American potash works were begun at port cities such as Boston, New York, and Philadelphia and were equipped with elaborate leaching vats, large furnaces for evaporation, and other equipment. These plants were fed with ashes purchased from local residents and outlying farmers. But the supply of ashes was irregular, and its quality varied, often resulting in poor yields.

The poor yields were mostly the result of a failure to recognize the large differences in potash content between soft woods and hardwoods, and even among the various hardwood species. Experience soon showed that elm, ash, sugar, maple, hickorv, beech, and basswood had the highest potash contents. In North America these species grew--and still grow--most abundantly in an area extending from New England north to Southern Canada and west to Minnesota. Little wonder, then, that attempts to establish potash works in Virginia and in Nova Scotia were bound to fail and that the plant at Philadelphia remained marginal at best. Pennsylvania was at the borderline for suitable wood.

Eventually, though, even in high-yield areas settlers stopped selling ashes to British-owned works, for, as a Boston-based potash maker lamented in 1771, "Our [suppliers] have got into the way of making up their own ashes into salts in the kettles they get to make [maple] sugar in and they find they turn their labor as well as their ashes into money so there is no getting their ashes…."

A new era had begun. From 1760 onwards colonists were moving in vast numbers into unsettled ,hardwood-rich northern New England and upstate New York. The typical homestead tract, or "pitch," consisted of one hundred to two hundred acres of nearly impenetrable virgin forest. One of the settler's first task was land clearing, and the fastest method was slash-and-burn clear-cutting. These pioneers soon realized that the heaps of wood ashes they were producing could be converted into "black gold" worth hard cash.

This new stage of home potash production depended on a much-simplified process, which could be carried out by the individual settler on his own pitch. In brief, the ashes from huge open fire of hardwood logs were gathered and leached and the resulting solution was then simply boiled down and melted into a crude black potash. Besides the necessary ashes and leaching vat, the critical element of this backwoods technology was the use of a thick-walled potash kettle, or"kittle." Before Ethan Allen began his adventures in Vermont with the Green Mountain Boys, he and his brothers had an ironworks in Salisbury, Connecticut, that specialized in potash kettles, and many of them can still be found around New England.

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This process was widely promoted during the American Revolution t increase gunpowder supplies. Gunpowder required saltpeter (potassium nitrate), which was made from potash and nitrogen-rich dung, such as bat guano. By the post-Revolutionary period potash manufacture had become a standard part of New England farming, and it was a critical source of cash to pay taxes and buy necessities in the depression years that followed the war. Even a single tree could bring up to four dollars this way, via forty pounds of potash carried to market by backpack.

But the forests were mostly cleared within a decade or two, and by 1790, at least in Vermont, farmers and house-holders
were down to cooking and heat ing ashes, produced from the fifteen to thirty cords cut annually from their wood lots. Moreover, to assure this fire wood supply, one-fifth of the typical farm had to be kept wooded. People began to try to extract more salts from these ashes and even to obtain potash from previously discarded waste ash. The potash industry was in crisis. Enter Samuel Hopkins.

Samuel Hopkins was born December 9, 1743, just north of Baltimore, the second child of Quaker parents. About the age of 16 he was apprenticed to Robert Parrish, a Philadelphia Quaker tradesman. In the spring of 1765 Hopkins married Hannah Wilson, a sister-in-law of Parrish. Over the next twenty five years in Philadelphia Samuel and Hannah raised six children. The Census of 1790 lists Hopkins' occupation as "Pott Ash Maker" while the city directories of this same period gives his trade as "pot-ash maker" or "pot-ash manufacturer".But becoming impoverished before the century was over, he and his wife took temporary refuge in Rahway, New Jersey, with their daughter Sarah and son-in-law, William Shotwell After returning to Philadelpia, Hopkins died in 1818, survived by his wife..[ in Nine Partners (now Amenia), New York, on May 12, 1765. In 1781 he moved to Pittsford, Vermont, and he lived there for the next thirty years, marrying a woman named Betsey and fathering seven children. In about 1810 he moved to Pittsford, New York. Betsey died there in 1813, and Samuel later married a local widow, Sarah Dunn. He died in 1840.] In addition to his first patent, Hopkins took out two later ones, both for a preparation of flour of mustard. And less than a year after the potash patent was granted, the Quebec Parlement passed an ordinance to "reward" him for his discovery. Legal experts now consider this Canada's first patent.

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Hopkins's key advance lay in burning the raw ashes in a furnace before they were dissolved in water. This second burning resulted in much greater carbonate formation, apparently because the free carbon in raw ashes (which partly accounts for the black color) was more completely oxidized and because of exposure to concentrated carbon dioxide gas from the fire. Hopkins also ncreased yields by mixing the insoluble residue from one batch with the raw ashes of the next, instead of simply discarding it. For a five-year license for a furnace using his process, Hopkins required a down payment of $50, or a half-ton of potash, and another $150, or a ton and a half of potash, over the next five years, payable to his agents in various cities.

With the Northeast's farmland mostly cleared and this new technology available for processing, the industry moved from individual farms to village-based asheries. The farmer had become too busy with other tasks, and a local ashery could invest in the necessary licenses, equipment, and skills maximize the yield.

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The new potash works were mostly run by village storekeepers. There a farmer's wife might sell her clean ashes for as much as fifteen cents a bushel, payable partly in cash, partly in trade. Those farmers still making potash could sell their "black salts" to such a works to be refined into the purer commodity. And as more American fulling mills using local wool began to open in the Northeast, they relied on barrel after barrel of soft soap from many asheries.

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During the fourteen-year term of Hopkins's patent, potash sold at from two hundred to three hundred dollars a ton, and over this period more than ninety thousand tons, worth at least twenty million dollars, were exported from the United States. We do not know how many of the thousands of asheries took out licenses under Hopkins's U.S. and Canadian patents, but if even a scant few dozen met his terms, he realized a handsome profit. Moreover, if the actual yields were anywhere near his estimates, this arrangement was a bargain for the asheries as well.

Until the 1860s, thanks in part to Hopkins, the United States remained the world's leading producer of potash. Then potash began to be mined from rich natural deposits (such as dry-lake alkali beds) in Stassfurt, Germany, and the U.S. industry came to an end. This German potash supplied nearly all American needs until the embargo of World War 1, when mining and salvage from ashes, kelp, and various industrial and food-processing wastes met the demand. In the 1920s and 1930s Germany again dominated the world potash market, but France, Russia, and Poland were important sources as well. American production from mineral deposits in New Mexico, California, and Utah was also increasing. During and after World War 2, these deposits allowed the United States to become self-sufficient in potash once again.

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The forest-based potash industry is now long gone, but it was essential in the early years of the nation, and Samuel Hopkins' patent permitted it to thrive. Potassium salts continue to be invaluable industrial and agricultural chemicals, and a stream of important patents concerning them has followed Samuel Hopkins's down to this day. Moreover, his exemplary disclosure, marketing plan, and license agreements, co authored by Shotwell as Hopkins' attorney-in-fact, set worthy precedents for all subsequent inventors.

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Henry M. Paynter is a professor emeritus of mechanical engineering at the Massachusetts Institute of Technology and is another resident inventor of Pittsford, Vermont.


Sources: Original Paynter article from INVENTION & TECHNOLOGY, Fall 1990;

            Maxey's corrections from The PENNSYLVANIA MAGAZINE of HISTORY & BIOGRAPHY, Jan/Apr 1998

             and from the JOURNAL of the PATENT & TRADEMARK OFFICE SOCIETY, March 1998.