Morton Salt was founded in 1848, originally selling salt, but it morphed into a salt manufacturer in 1910. Its logo and slogan, developed shortly thereafter, are a little strange for a salt company, though. The slogan, “when it rains, it pours,” seems like a bad thing — rain isn’t the most pleasant of weather and a downpour is even worse. The logo doesn’t help: it depicts a girl in yellow, holding an umbrella that is shielding her from the rain — but she’s spilling the salt she is carrying under her left arm. Why would a company want to be affiliated with a wet mess? Well, it didn’t. Morton Salt wanted to be known for a scientific breakthrough that we now take for granted: a salt shaker that works when it’s rainy out.

Let’s start with the problem. Take some salt, get it just a little wet (really, a drop will do), and you’ll see that it cakes together. That’s bad if you’re in the table salt business, as clumpy salt doesn’t pour very easily. The obvious solution is to keep the salt dry, but that’s harder than you’d think. Regular old table salt, as the New York Times notes, it’s hygroscopic; “because of the net positive charge of its chemical components, or ions, it can attract atmospheric water, which has a net negative charge.” In other words, when it’s humid out, salt clumps. And when the weather is rainy, it’s humid. Or, as salt users the world over used to observe, when it rained outside, the salt inside wouldn’t pour — it had clumped together too much.

In 1910 or 1911, Morton came up with a solution: adding magnesium carbonate, a compound that absorbed the water molecules and kept the salt grains from caking. This gave Morton a competitive advantage, and they wanted to let the world know. As Morton’s corporate website explains, they took out ads in Good Housekeeping magazine touting their superior salt. The original copy for the ad read “even in rainy weather, it [the salt] flows freely,” and once some wordsmiths got involved, it became “when it rains, it pours.” The girl under the umbrella told the story visually — any other brand of salt, positioned similarly during a rain storm, would hardly have flown out of the container. The logo and slogan are showing a breakthrough in salt science — one hailed by consumers. Even a century later, Morton Salt is North America’s most popular salt brand.

Even today, Morton and many other table salt brands add something to their product to prevent the caking problem, although the additive is now commonly calcium silicate. It basically does the same thing as magnesium carbonate — but, as Wikipedia notes, is also used “as a safe alternative to asbestos for high-temperature insulation materials,” in case you were wondering.