Digging up our chemical past

In the forensic laboratories of the 1920s, a chemist checking for poison could make a beaker glow with the brilliance of a gemstone.  Color tests, as they were called, derived from the fact that many toxic materials turn a specific hue if exposed to the right mixture of heat, cold, acid and base. The results can be eerily beautiful: the gorgeous blue of cyanide, the crimson of carbon monoxide as it saturates blood, the peacocking green of arsenic.  A  journalist, watching some tests, once compared the lab at the New York City medical examinerâs office to the glitter of Aladdinâs cave.

He was right about the gaudy effect: poisons shone like a fantasy of lights in the laboratory. But that was mostly because there were just so many of them. A wealth of newly lethal compounds were created in the early 1900s, harbingers of a chemical century. The new materials came from the military innovations of World War I, from the needs of industry and agriculture, and medical research. Some even grew out of the speakeasy culture fostered by Prohibition, with its smoky jazz clubs and secretive and occasionally lethal cocktail recipes.

We tend to assume that we've left this era of chemical experimentation and vulnerability behind. It's true that forensics laboratories are far more sophisticated, that color tests are a thing of the past. It's true that we've learned to regulate chemical compounds far more vigorously than occurred in the early 20th century. But it's also true that we still live in a chemical culture, develop new compounds, still struggle to understand their implications in our daily lives.

And, as recent U.S. Army excavations in Washington D.C. remind us, we may occasionally also encounter some of the worst of our chemical history in our daily lives. Since January, the Army has been working to clean up a former military chemical disposal site discovered in the yards of homes (expensive homes) in the Spring Valley neighborhood near American University. In fact, a major excavation is underway in the front yard of a home next door to that of the university president's residence.

During World War I,  American University served as an experimental research station for the U.S. military's development of poison gases. The war, which lasted from 1914 to 1918, was the only major conflict in which combatants attacked each other by bombarding troops with containers that released toxic gases. The most notorious of these was mustard gas, developed by the Germans, which settled onto soil and soldiers alike,  with a sulfuric-acid rich vapor that blistered through skin eyes and lungs.

Army researchers at American University and elsewhere countered by also developing mustard gas in this country. And Friday, a military spokesman announced that a container of mustard agent was dug up earlier this month at the Silver Valley excavation. But it was also revealed that the digging was halted on April 8 when workers turn up glassware smoking with an unknown compound.

That compound has now been identified as arsenic trichloride,

AsCl₃, a compound made up of the two poisonous elements arsenic and chlorine.  What makes it especially interesting is that arsenic trichloride was an ingredient in an experimental gas called Lewisite, which the U.S. hoped would be an even worse blistering agent than mustard gas. Eventually all agreed that mustard gas was a more effective battle agent.

And also that it was a horrifying weapon, which indeed it was. Before World War I, international treaties had been signed to ban such chemical weapons. The Great War, as it was called, provided a vivid, lethal, destructive demonstration of why poisonous warfare was such a terrible idea. In 1929, nations around the world signed treaties at the Geneva Convention, which again prohibited gas warfare, and barring a few regional conflicts, these prohibitions have been widely respected.

But the legacy of gas warfare in World War I remains - physically, as this year's excavations in our nation's capitol remind us, ethically and morally.  We haven't left our chemical past quite as far behind as we might think.