Resource

Ice Cream Maker Patent

An inventor harnesses the principles of thermodynamics to bring a beloved dessert to the masses.

“No. 3,254 Artificial Freezer”

N. M. Johnson, “No. 3,254 Artificial Freezer,” September 9, 1843. United States Patent Office.

Document Text

Summary

UNITED STATES PATENT OFFICE.

NANCY M. JOHNSON, OF PHILADELPHIA, PENNSYLVANIA.

ARTIFICIAL FREEZER,

Specification of Letters Patent No. 3,254, dated September 9, 1843; Antedated July 29, 1848.

To all whom it may concern; 

Be it known that I, NANCY M. JOHNSON, of the city of Philadelphia and State of Pennsylvania, have invented a new and useful Improvement in the Art of Producing Artificial Ices, and that the following is a full and exact description of the machinery for carrying into effect the said improvement.

I, Nancy M. Johnson, from Philadelphia, PA, invented a new machine for making ice cream. Here, I will describe the machine and what makes it unique.
Instead of causing the freezer or vessel A (see the accompanying drawing) which contains the substance to be frozen to revolve ice and salt mixture, by the hands of the operator, I place within it a vertical shaft as heretofore has been practiced, within the or axis B, reaching to the bottom and coming up a short distance above the cover of the freezer, through which it passes in a tube C, traversing centrally, the lid and its handle, which tube thus becomes the upper support of the said shaft or axis–the top of this shaft or axis is terminated by a square shank D, on which after the lid is placed over it a crank E having a wooden or other nonconducting handle can be placed to give motion to the shaft. Following the provided diagram, you will see that this machine uses a simple handle to turn a tube inside the freezer chamber in order to freeze the ice cream.
On the shaft below the lid of the freezer are two or more wings F, F, extending to the bottom and reaching horizontally nearly to the sides of the same, these Wings are generally perforated with a number of holes about half an inch or more in diameter; when but two wings are used they form together a curved figure by their horizontal cross section resembling the letter S reversed, thus 3, so that when the revolutions are made by carrying the hand from right to left between the axis and the operator, the vertical edges of the beater tend constantly to carry the liquid or semi-fluid mass from the center to the circumference of the containing cylinder or freezer and that on the contrary when he turns the crank from left to right between himself and the shaft, it will tend to cut off any frozen matter from the inner surface of the freezer and to gather. it toward the central parts, thus constantly allowing fresh portions of the cream or other substances to be frozen to come in contact with the refrigerating surface. The way the machine is designed prevents the material that has already been frozen from getting stuck to the inside of the machine. Everything continues to move around inside the cylinder so all parts of the ice cream mixture can be frozen.
To confine the freezer itself and prevent its revolving with the beater when the materials within it become stiff, the handle on the lid G is embraced in a groove or cavity H. formed in the under side of the cover which is placed over the wooden tub or box I, within which the freezing is conducted. This cover is itself prevented from turning by notches a, a which take hold of the two ears, b, b, of the tub, the tub being thus covered, the Salt and ice as well as the freezer and its contents are defended from the heat of the air and of the person of the operator. The lower end of the shaft of the beater is generally formed into a rounded pivot resting in a corresponding cavity in the bottom of the freezer. The lid is designed to prevent the handle from getting stuck and seals well so that the contents of the container do not begin to melt. The beater fits into the bottom of the freezer.
 I do not confine myself to any particular material in the construction of the freezer or beater for lemon, orange and other juices containing acid which might react slightly upon tinned iron, I prefer glass cylinders for freezers and hard wood or ivory for the Wings of my beater, for cream and other substances which are not acid in their properties, the thickest of tinned iron is the most suitable material of which to form the beater. There is no one material that is best to use for creating the freezer, as different foods may react to different materials.
When the substance to be frozen is placed in a freezer formed of two concentric cylinders and having ice and salt in a central cylinder the beaters may be attached to horizontal arms on the main vertical axis and go down on opposite sides of the central refrigerating cylinder. Place the mixture you would like to freeze into the freezer, which has a central cylinder filled with ice and salt. When the beaters are turned, the material will be cooled by the central cylinder.
In Seasons and at places where the economy of ice and salt is important, I make use of a tub or box whose diameter exceeds that of the freezer only by three or four inches and by closely wrapping this in several folds of thick Woolen blanket, or blanket padded with wool, fur or some similar material having a low conducting power for heat, I am enabled So to defend the contents of the same from the action of external heat as greatly to diminish the quantity of these materials necessary to produce and maintain the low temperature required for congelation. For added insulation, the freezer can be wrapped with a blanket and placed in a box. This will keep the salt and ice from melting quickly.
 When the economy of salt is particularly important, I effect it by evaporating the salt water derived from the salt and ice, thus making a very limited quantity of salt serve for an indefinite number of successive operations. If the user only has a little salt, they can evaporate the water out of the freezer when the ice cream is finished and reuse the left over salt.
What I claim as new in this my invention and for which I desire Letters Patent is-

The above described revolving curved beater with its vertical axis, in combination with a freezing apparatus as above described and adapted to the purpose herein set forth.

These are the inventions that make my machine worthy of a patent: a curved beater which turns around a vertical axis, combined with an apparatus for freezing things.
Nancy M. Johnson.

In the presence of John Thompson, Samuel Day.

Background

Ice cream was served in the U.S. all the way back in the colonial period, but it was very difficult to make. This meant that very few people could afford to enjoy it. All of that changed in 1843 when inventor Nancy M. Johnson patented her artificial freezer. Her invention was a new kind of churn that made it easier to freeze the ice cream while it was being made. It also was capable of making two flavors of ice cream at the same time. Nancy’s invention revolutionized the ice cream-making process by harnessing the principles of thermodynamics. The machine made ice cream a dessert all Americans could afford to enjoy.

About the Document

In the opening of the patent application for her new ice cream maker, Nancy M. Johnson proudly listed herself as the inventor. At the time, the legal principle of coverture meant that women were still widely considered the legal and economic dependents of their fathers and husbands. American women inventors of the past filed patents in their husbands’ names to avoid rejection. But Nancy’s decision to list herself as the inventor, and the patent office’s acceptance of her application, reflects the new attitude toward women’s autonomy that was gaining ground during the 1800s.

Vocabulary

  • patent: A government-issued license giving someone sole rights to their invention.
  • thermodynamics: The science of heat and other forms of energy.

Discussion Questions

  • According to the patent, what makes this invention unique?
  • Why is this invention important in the history of American culture?
  • Why is it important that Nancy M. Johnson listed her own name on the patent application?