A loading scale worth about $2,000 was stolen early last week from a room in the Mallinckrodt Laboratories, police said yesterday.

Workers in the laboratories, which are used by chemistry students for graduate and post-graduate research, discovered that the Mettler PC 2000 loading scale was missing on Monday morning May 8, according to police.

The scale was about two feet long and a foot wide, said Alan K. Long, the director of the laboratories. Although he said someone carrying it under their arm would be "very suspicious," he added that the laboratories are "a big place and very difficult to maintain."

Police have not apprehended any suspects.

Long said he thought that it was "very unlikely" that the culprits were students or laboratory employees. He said the criminals were probably using the scale, which was not one of the laboratories' more precise "analytical" devices, to weigh and "market on their own" certain illegal colorless chemical powders.

Long said he has no idea how the culprits got into the building. "We always try to maximize security," he said. "We lock the building doors on the card key system, and they're locked all weekend."

Although the laboratories do not have anelectronic security system, Long said HarvardUniversity security guards patrol the complex whenit is closed to the public.

But, with 500 people passing through the doorsof the five-building complex that includes theMallinckrodt laboratories, the guards "can't watcheverybody all the time," Long said.

Long added that "guards are expensive" and theyare unable to afford enough to watch all 11entrances.

"There are a lot of incidents on the weekendswhen there are fewer people here," Long said.

Long said that scale thefts happen "prettyfrequently." Three or four scales or computers arestolen from the laboratories every year, he said.The laboratories have even more expensiveequipment, but most of it is not as portable,according to Long