Those rumors about strange experiments being conducted in the Technological Institute are true — sort of.

Screams and spooky music drifted through Tech on Thursday as chemistry lecturer Eberhard Zwergel and other science faculty members presented the 14th annual chemistry department Halloween lecture to four different audiences.

About 300 people crowded into the aisles at the 11 a.m. show to see Zwergel and the others present 23 Halloween-themed experiments.

Five undergraduate students clad in devil costumes assisted the experiments, which included lighting a rainbow-colored fire and igniting hydrogen-filled balloons that exploded in a flash of colors.

“It’s magical but not magic,” Zwergel said. “It looks like it’s just happening but everything can be explained.”

Chemistry profs. Tom O’Halloran and Franz Geiger emceed, explaining the chemical background for each experiment.

O’Halloran said he began the Halloween lecture about 14 years ago with only a few experiments.

“Eberhard has made it into the masterpiece that it is,” he said.

With Zwergel’s help, the lecture has evolved into a theatrical event. A group of graduate students decorated the lecture room like a haunted house, complete with strobe lights, jack-o’-lanterns and balloons.

The Miller Trio played eerie Halloween music, blending violin, keyboard and viola, while the Northwestern University Marching Band and an a cappella group performed between experiments. Three members of the Lady Cats danced throughout the show.

Most experiments involved chemistry, but the lecture also included other subjects.

Physics lecturer Art Schmidt joined the group about eight years ago and added physics demonstrations to the presentation. In one demonstration, he shot a ping-pong ball across the room after releasing it from a vacuum.

This year’s lecture was the first to include biology, and lecturer John Mordacq showed audiences images of his genetically engineered glow-in-the-dark worms.

Mike Reczek, a McCormick freshman and chemistry student, said the program was well-organized.

“It helped us visualize what we’re learning and fortified what we see on paper,” he said. “And (it was) really cool.”