The BackBlog: The Mystery of the Babcock Tester

By , February 11, 2020

I found this device in a box labeled “Misc. Med Equip / Early Autoclave? / + other un-Id’d stuff”. None of the labels on the box seemed quite right for this instrument. It didn’t look exactly like anything I had come across before. Luckily, the name of the object was right on the side, so it didn’t take too long to figure out what it was. The reason I couldn’t place it was that it wasn’t a medical device at all. It was an agricultural device.

Photo of a babcock tester, with a hand-crank and two centrifuge tubes

Hand-cranked Babcock tester, 1890-1940. From the Warren Anatomical Museum in the Center for the History of Medicine, Francis A. Countway Library of Medicine (LEAN0931)

The Babcock Tester was developed in 1890 by Stephen Babcock to detect fat content in milk. The test was simple: place graduated vials of the milk you are testing into a centrifuge like this one and spin them until the milk is separated. Once the milk has separated, you can see the amount of fat that is present in the sample. This tester is a hand-crank model designed for a tabletop, but other iterations included covered centrifuges and table clamps. Sometimes, sulfuric acid was used to remove proteins and other milk components, leaving just the fat.

For the most part, the Babcock test was used by farmers to check the quality of their milk. Sometimes, it was also used to make sure that dairy farmers weren’t diluting their product to stretch the amount of milk they had. The test became incredibly popular and was the primary method for testing milk fat for decades. Not only was it easy and effective, but Babcock refused to patent the device. That made it accessible and affordable as well.

So, if this is an agricultural device, how did the Babcock tester end up in a medical museum? The answer is, we’re not sure. We don’t have any background information on who donated the object or what it was used for.

There are several reasons this Babcock tester could have been collected. It could have been part of a public health initiative regarding nutrition from milk. There might have been a particular physician who was interested in this aspect of nutrition. It’s also possible that someone used this device as a centrifuge for something other than its intended purpose, and it has nothing to do with milk. Hopefully, we will find more information about this device someday, and we will learn how it ended up here. For now, we can only speculate, and the Babcock tester remains one of the mysteries of the backlog.

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