Preventing Breakage of Crucible Lids When a crucible containing a precipitate which has been filtered through paper is heing ignited, the crucible is inclined at an angle in a clay triangle. The crucible is partially covered with its lid, which is tilted at an angle against the crucible. This is at best a metastable condition with the lid supported a t only one point on the hottom. Lids frequently fall off and are broken. Two solutions to this problem are suggested here. 1) A piece of 0.70-mm diameter steel piano wire (Nichrome can also be used) is inserted through one side of the clay triangle and wrapped tightly once around the wire support and hent a t an angle of about 45" to the support wire. The end of the wire is hent upward perpendicular to the plane of the triangle. This procedure is repeated to give two wires in support. The crucible now has three points of support on the bottom (see photographs).
2) One of the support wires is partially untwisted, and the two strands are separated a t about a 4 5 O angle and each end is bent upwards. (Since some of the length of the support wire is lost, the triangle may not fit the iron ring used previously for support.)
Louis H. Adock Unlverslty of North Carolina at Wilrnington Wilmington. NC 28403
Volume 62
Number 7
July 1985
809
