6What Volcano Blackened the World, Half a Millennium Ago?

When we dig through the ground and analyze mineral records, we can learn all sorts of things about the distant past. We can also learn about the comparatively recent past, a time otherwise thoroughly covered by historical records. When we dug into the ice in Antarctica and Greenland, we discovered deposits of sulfur that had once been in the air. This pointed to a major volcanic eruption, which we calculate must have happened in the year 1458.

Columbus was seven years old. This was very much the era of recorded history.

The word “major” in the previous sentence understates this event, hugely. This eruption added roughly as much sulfur into the atmosphere as the 1815 Tambora eruption, whose similar sulfur spewing resulted in the northern hemisphere missing summer because the ash blotted out the sun. Worldwide famine set in, as it did following the 1458 eruption as well. We know which volcano erupted in 1815 (Mount Tambora, in Indonesia). So, which volcano erupted in 1458? We don’t know.

It seems like we should know. An eruption that big should have created immediate columns of ash 15 miles tall and would have been audible a thousand miles away. However, we don’t have records from anyone who saw or heard it. The eruption also created a tsunami that devastated some coast. We know it did, because it must have; we know how seismic events of that magnitude function. But here as well, we don’t have records from anyone who got swept up in that.

The records all got swept away, too

The volcano probably stood in the tropics, and we thought we had a good lead for a while. The people of Tongoa Island in the Pacific had oral records of some massive volcanic blast in the 15th century. But we investigated and found that happened slightly earlier in the 15th century and wasn’t nearly as big as what we were looking for. Confusing matters further, we stumbled on another enormous volcanic eruption, separate from the Tongoa one or the 1458 one. It happened in 1452 or 1453 and also led to worldwide effects and widespread famine. We don’t know where this one happened either.

If any of you were alive in the 1450s and witnessed either of these eruptions, please contact the United States Geological Survey at 1-888-392-8545 to send in your tip. Anonymity guaranteed.

5What Does pH Mean?

The pH scale measures how acidic a solution is. Or rather, it measures how acidic a solution isn’t — if something has a pH of 0, it’s extremely acidic, and if it has the max pH of 14, it’s extremely alkaline. You know all about the pH scale if you use quack remedies that promise benefits from balancing the pH in your body.

“For real balance, here’s some alkaline water, with lemon!”

If you’re a student of chemistry, you know how to calculate pH from the concentration of ions in a sample. But do you know what the letters “pH” stand for? No, you don’t, and neither does anyone else alive.

The H stands for hydrogen — that much, we know. But the p? It doesn’t stand for “percent,” though pH does measure the proportion of hydrogen. Nor, for that matter, does it stand for “proportion.” Many people think it stands for “power,” because pH takes into account exponents, which we sometimes describe using the word power. It can’t, though, be power either (pH is the negative logarithm of hydrogen ion concentration, so “power” is really a bad way of describing anything here).

Maybe the p stands for… pee. Pee has pH, right?

Various urban legends say it stands for various foreign words, like puissance, Potenz, pouvoir, potential and pondus. Some theorize that it means “positive,” relating to which electrode negative ions move toward, or that it might simply be the letter p, because n and o already represent other stuff. The only person who knew the real answer was chemist Søren Sørensen, who coined the term pH in 1924. He died in 1939, and during those last 15 years, not one person asked him why he’d named it that. Hey, we get it. Most of us avoid asking chemistry teachers anything if we can help it.