/oss/taxonomy/term/661/all en /oss/article/technology-general-science/oh-bathtub-ring <p>In 1933 Calgon Incorporated of Pittsburgh introduced its flagship product, appropriately named “Calgon.” The name was derived from the phrase “calcium gone,” which was an accurate description of what the product was designed to do, namely soften water. Hard water has a high content of dissolved minerals, mostly salts of calcium and magnesium. Various problems ensue when the concentration of these is greater than about 120 mg per liter. Unlike the sodium salts of fatty acids that are the basis of soaps, their calcium and magnesium salts are insoluble, resulting in the classic bath tub ring.</p> Wed, 16 Oct 2024 19:49:35 +0000 Joe Schwarcz PhD 10115 at /oss /oss/article/you-asked/rust-stains-your-bathtub <p>If you see reddish stains in your sink, bathtub, or heaven forbid, on your laundry, it's a good bet you've got iron in your water. Don't look for nuts and bolts dripping from your tap, this kind of iron is dissolved in the water. Where does it come from? Water is a great solvent and as it percolates through iron-rich rocks and soil and flows through pipes on its journey to your tap, it dissolves iron. We refer to this kind of iron as "ferrous" but it is not the only form of iron that can be found in water. "Ferric" iron is insoluble and occurs in water in the form of tiny particles.</p> Tue, 06 Nov 2012 17:10:43 +0000 Joe Schwarcz PhD 1747 at /oss