Sensing Change

Today we may take for granted the safety of the water that comes from our tap. Filters that attach to a faucet or rest inside a pitcher remove even more of the hidden contaminants in our water. But not so long ago water’s purity was determined solely by its taste, and water’s safety could not always be assumed. Although the network of waterways and purification systems that water travels through to get to us is complex, it can be found with a bit of legwork. The journal of high-school student Clara Hartley, written in 1896, shows how testing of water just a walk away from home could be done.

What makes up water? Are all waters equal? In the slideshow above, view not just sections of Clara’s journal but also sections of the publications created in 1887 by members of a special Water Analysis Committee from the Chemical Society of Washington. These documents explore water’s properties and our ability to understand its contents. We’ve come a long way in our ability to analyze our water—and to trust its safety—and these 19th-century documents help us understand the history of the simple tests we perform to learn about our water’s chemical makeup.