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230th birthday of the inventor Nancy M. Johnson

Ice cream for everyone!

Ice cream is probably the most popular and widespread sweet treat in the world. But it was once an extremely exclusive goodie that only a few could afford. Ice cream for everyone has only been around since Nancy Johnson. In 1843, she invented a device that made it relatively easy to prepare ice cream at home. She received a US patent for it - making her a pioneer not only in the history of ice cream, but in the history of technology as a whole.

Ice cream has been known as a luxurious treat for centuries - even Roman Caesars and Chinese emperors enjoyed it. For a long time, this was refined natural ice, i.e. frozen water or snow. Later, milk ice cream was developed. For this, an ice cream mixture had to be laboriously stirred by hand for hours in a double-walled container surrounded by lots of natural ice. This ice cream was sold at a very high price.

Missionary, teacher, inventor

Nancy Johnson put an end to this. Not too much is known about the inventor: She was born Nancy Maria Donaldson on 28 December 1794 (probably somewhere in the state of New York, unfortunately it is not known for sure). Together with her sister Mary, she was involved in the ‘American Missionary Association’. In 1823, she married the natural scientist Walter Rogers Johnson (1794-1852), who would later play a leading role in the American Association for the Advancement of Science. The couple, who lived in Philadelphia, adopted two children.

And those must have been particularly pleased with what their mother applied for a patent for on 9 September 1843: she called her invention the ‘Artifical freezer’ ( US3254A) - a hand-cranked ice cream machine!

Thermodynamic trick

Johnson's ‘freezer’ utilised the principles of thermodynamics and endothermic reactions. The wooden vat, which resembled a butter churn from the outside, contained a metal cylinder for the ice cream mixture. Between the cylinder and the outer wall was a mixture of salt and crushed ice. As salt lowers the melting point of liquids, it caused the ice to melt, but at the same time lowered the temperature to below freezing. This extracted heat energy from the mass in the cylinder, causing it to freeze (the same principle is recommended today by numerous ‘hacks’ on social media, for example to cool down beer very quickly).

A hand crank was used to rotate a stirring arm with two curved, perforated plates inside the cylinder. This ‘beater’ or ‘dasher’ was used to move the ice cream mass evenly without much effort; above all, however, the ice crystals that formed on the walls of the cylinder due to the external cooling were scraped off and mixed in.

The finished ice cream remained cold in the freezer for around 30 minutes, so it was only suitable for immediate consumption. The appliance could also be used to make sorbet.

Ice, ice, baby!

That was the ‘ice cream revolution’. Johnson's design simplified and accelerated the production of ice cream considerably. It even tasted better, as the beater made it airier and creamier. It also required much less natural ice and salt than before. Electricity was also not required. Ice cream was now much cheaper - almost every household could now produce good ice cream themselves. Ice cream went from being a highly exclusive luxury product to a treat for everyone.

The fact that Johnson applied for a patent for her invention herself and in her own name (and not her husband's) was still very unusual at the time. She demonstrated a real pioneering spirit. However, Johnson was unable or unwilling to commercialise her invention herself. She sold the patent rights to a certain William G. Young from Baltimore. She received 1,500, according to other sources even only 200 dollars. In any case, far too little for an invention that has hardly changed and is still in use today!

Nancy Johnson remained a housewife. From 1862, she and her sister taught former slaves in South Carolina as part of the ‘Port Royale Experiment’ education project. Unfortunately, not much more is known about her life. She died at the age of 95 on 22 April 1890 in Washington, D.C.

Hand-cranked ice cream makers like Johnson's are still around today, but most people would probably prefer an electric, and unfortunately less environmentally friendly, appliance at home, such as the „Haus-Eismaschine“ (Home ice machine, DE212021000321U1 (2,27 MB)).

Text: Dr. Jan Björn Potthast, Pictures: DEPATISnet, unbekannter Fotograf, Public domain via Wikimedia Commons, gmhofmann, Public domain via Wikimedia Commons

Last updated: 6 December 2024