This post was written by Peter DeCraene, a 2021-22 Albert Einstein Distinguished Educator Fellow at the Library of Congress.
As winter sets in and holidays approach, my mind turns to the comfort of baking. When I have not had the exact ingredients a recipe called for, I have sometimes improvised substitutions. Changing flavorings was not a problem, but altering the chemistry of the recipe led to rock-hard cookies or cakes that overflowed their pans and left burned splatters in the bottom of the oven.
I quickly learned that the raising agents in dough, like baking soda, baking powder, or yeast, are definitely not interchangeable. When I saw this trademark registration, for “Horsford’s Self-Raising Bread Preparation,” my curiosity was piqued, and as I started to notice and think, I wondered what my students might see in the item, and how I might engage them with it.
Looking at this item raised so many questions for me:
- What is in this “bread raising material”?
- Why were some of the sections printed sideways?
- What might have appeared under the last line, “Prepared according to the directions of Prof. E. N. Horsford, by the” that suddenly cuts off?
- When I think of “chemical works” I think of some industrial plant; what else was produced at Rumford Chemical Works?
- What’s the difference between a trademark and a patent?
My hypotheses about this item and the questions it raised led to some additional research across subject areas. Supporting students in close observation and wondering might prompt them to pursue their own research.
Mathematically, the statement “This package contains enough for 25 lbs. of flour,” hints at volume and ratio questions. It also led me to the assumption that this item was a label for the package.
- What were the dimensions of this container if it had been a circular canister? What if it had been a rectangular box?
- How much was in this container?
- How much would be used for one pound of flour?
The chemistry of baking powder is also interesting. Baking powder is a combination of chemicals that produce carbon-dioxide bubbles through an acid-base reaction. One of those, listed on the label as “Pure Bi-Carbonate of Soda,” is what we today call baking soda. The label also lists a “cream of tartar substitute” but does not specify what this contains. Some chemistry questions might be studied here:
- What are the different ingredients in baking powder, and in what amounts?
- Why don’t the chemical ingredients react with each other in the can?
- Research into this product revealed it was “double-acting”; how does double-acting baking powder work?
Historical and sociological questions also arise from this item:
- This Self-Raising Bread Preparation has several patents in addition to this trademark; what is the difference and significance of these registrations?
- What else did the Rumford Chemical Works produce?
- Since the actual ingredients are not listed, I wonder if other companies had different recipes for baking powder?
- Baking powder was invented in the mid-19th century; what effects, if any, did the invention have on industry at that time?
With a little research, I found that one of the ingredients in some baking powders was pearlash, a potassium carbonate compound related to potash. Potash was an important export from North America to Britain in the 18th and 19th centuries, and the first U.S. patent, issued in 1790, was for a new method of making potash and pearlash. (And the history of U.S. patents is a wonderful lens for looking at American history!)
This one item led me to many cross-curricular explorations. Download the high resolution version of the image and let your students observe, reflect, and wonder about it, and see what rises from their curiosity. Right now, I’m curious if I have all the ingredients for some chocolate chip cookies.