Abstract: A clamp for securing ground-glass joints between first and second tubes, the first tube having a shoulder located inward of its end, intermediate the ground and unground portions thereof, adjacent the ground joint, and the second tube having an enlarged lip located at its end adjacent the ground joint and the shoulder of the first tube. The clamp has an mounting portion and an attaching portion having first and second parts for accommodating the shoulder and the enlarged lip therebetween, followed by a releasing portion. The mounting portion connects the first and second parts and has forward ends extending substantially symmetrically along a longitudinal axis of the clamp. The forward ends of the mounting portion are biased toward one another by the clamp. The first part of the attaching portion is an attaching collar for partially fitting around the circumference of the first tube adjacent the shoulder rearwardly of the transverse axis.