Nancy M. Johnson (inventor)

Nancy Maria Johnson ( Donaldson; December 28, 1794 – April 22, 1890) was awarded the first US patent for a hand-cranked ice cream freezer in 1843.

Biography
Together with her sister Mary, Nancy Donaldson volunteered for the American Missionary Association. She married Walter Rogers Johnson (1794-1852) in Medfield, Massachusetts in 1823. The couple adopted two children, Walter W. Johnson (1836-1879) and Mary Maria Stroud (1834-1921). Walter Johnson was a scientist and the First Secretary for the American Association for the Advancement of Science.

She started as a housewife, and later went on to be a very successful inventor, which was very uncommon in her days. During this time, women’s legal identities were taken away when they married, according to the laws of coverture. Women were not allowed to control their own finances, own property, or sign legal agreements. This was all done by the men. Men were looked at to represent their wives, mothers, and daughters.

Johnson lived in Philadelphia in 1843 when she filed for her patent for the first hand-cranked ice cream churn (US3254A). Her simple invention launched a “disruptive technology” that made it possible for everyone to make quality ice cream without electricity. Starting in 1862, Johnson and her sister Mary taught freed slaves in South Carolina, as part of the Port Royal Experiment. She died in Washington, D.C., in 1890, aged 95. The family is buried at Oak Hill Cemetery in Washington, D.C.

Invention of the ice cream maker
Ice cream was originally made using very intensive labor and it often took one individual hours to make. Johnson had invented the hand cranked ice cream churn as a way to make ice cream faster and easier than by hand.

The patent number for the Artificial Freezer is US3254A. It was patented on September 9, 1843, and antedated on July 29, 1848. The Artificial Freezer contained a hand crank, which, when cranked, would spin and rotate two adjacent broad, flat slates containing an array of holes, which would assist in churning the ice cream, making the ice cream more uniform, while also making it easier to remove the ice crystals in the interior walls of the cylindrical container in which the spatulas were fit in. These metal spatulas were attached to this pipe called the “dasher”, which was attached to the handle crank protruding out from the Artificial Freezer. Harnessing the principles of thermodynamics and endothermic reactions, Johnson’s Artificial Freezer was very effective in making ice cream. The wooden tub contained a mixture of salt and crushed ice, thus melting the crushed ice, but dropping the temperature of the solution below freezing point as a result of salt lowering the melting point of liquids. This, in conjunction with the ice cream solution, extracts heat energy from the ice cream, in turn freezing it. Johnson also was able to create the Artificial Freezer so that when using a border to split the machine down the middle, two different flavors of ice cream could be cranked and made at the same time.

In the "artificial freezer", which was the name of the original patent, it was possible to make either ice cream or sorbet, that would last about 30 minutes. There were no electric solutions to keep things cool, as the refrigerator had not been invented and not everybody had an icebox.

With these elements combined, it made it much easier, more efficient, and less labor-intensive for ice cream parlors to produce ice cream. Thus, a more efficient solution made it cheaper to produce ice cream, which in turn, made the ice cream cheaper. This granted accessibility to this dessert across all economic classes, which previously was too expensive for middle and lower classes as the production of the ice cream made it too expensive.

Johnson received US$1500 during the course of her life for her patent. She made her final changes to her patent on September 9, 1843. Despite Johnson's success and future impact she had with the Artificial Freezer, she sold the rights of the patent to William G. Young, a Baltimore native, who then improved on the ice cream freezer on May 30, 1848. Johnson sold the rights of the patent to Young for US$200. Some of the improvements included a similar internal spatula covered with holes, however, the mechanics of the handle were changed make the ice cream much cooler, also simultaneously speeded up the process of freezing.

Today, ice cream is one of the most popular desserts in the world. In 2019, about 6.4 billion pounds of ice cream and frozen yogurt were made in the U.S. Also, the ice cream industry has a major impact on the U.S. economy as it generates about 28,800 jobs and about $1.8 billion dollars in direct wages.