Gravesande's Ring

Apparatus devised to demonstrate the volume expansion of solids by heat. It consists of a metal ring which will just allow a metal ball to pa through it at the ordinary temperature. If the ball be heated over a spirit lamp, it expands and will no longer pa through. If it be allowed to rest upon the ring for some min minutes, the latter gradually becomes heated, expands, and the ball then drops through. IMG:content-0383.png:[graphic] IMG:content-0384.png:[graphic] Graves' Disease. Exophthalmic goitre described by Graves, an English physician.