In these experiments the general method pursued was by direct contact and separation of two circular plane metal disks, the lower one of which was insulated and connected to one pair of quadrants of a Thomson quadrant electrometer. The upper disk or plate of this condenser arrangement pressed during contact on the lower by its own weight, and was in connection with the other pair of quadrants and with the earth. The lower plate formed the upper surface of a cylindrical flask, whose temperature was determined by that of the water contained within it.