A boom was heard through the Honolulu Civic Center complex near downtown last night as a hazardous-materials expert did a controlled detonation of a jar of picric acid that had become unstable and potentially explosive.

Police closed surrounding streets for 20 minutes while Rusty Nall, vice president of PENCO Pacific Environmental Corp., placed the 1-pound mayonnaise-size jar of dried-out picric acid in a foot-deep hole on the lawn of the state's Kalanimoku Building and blew it up at 8:25 p.m.

The jar of acid was found at 10:30 a.m. yesterday on the third floor of the Department of Land and Natural Resources building at 1151 Punchbowl St., said Dave Curtis of state Civil Defense. The jar was secured and Department of Health officials contracted PENCO to destroy it last night.

Picric acid is commonly used in chemistry labs to stain microscope slides. As a liquid it is harmless, but if left standing for many years, it dries and becomes trinitrophenol, a highly explosive substance that's toxic when absorbed through the skin.

"It's one molecule off from TNT," said paramedic Randal Tanaka of the city's Emergency Medical Services "strike team" that stood by as Nall disposed of the chemical. "A little friction and ... boom."

Nall brought the jar down from the third floor in an explosive magazine container, transferred it to a plastic cooler near the steps and carried it to a hole that had been dug in the Kalanimoku Building's diamondhead-side lawn. After taking it out of the cooler, Nall held the jar in his hands to wrap the detonating cord around it.

"That's always the scary part," said Nall, the man who in 2002 boarded the burned-out Indonesian tanker Insiko 1907 to rescue Hokget the terrier dog. He also was hired to scuttle the Insiko.

Reach Rod Ohira at rohira@honoluluadvertiser.com.