Standard Specification for Crucibles, Ignition, Laboratory, Metal

This specification covers two types of metal ignition crucibles, nickel or platinum, complete with covers, for laboratory use. Two types of crucibles shall be classified according to their capacities: Type I is nickel with capacities of 100 mL and 250 mL and Type II is platinum with capacity of 20 mL. Type I are crucibles and covers which shall be made from 99.4% nickel, spun and hardened and Type II are crucibles and covers which shall be made from 99.9% platinum plus iridium, with the iridium content of not more than 0.4%. The crucibles shall have a standard shape with a flat base to give a firm and stable resting surface. The side wall shall form a sloping and convex surface extending up to the brim. Crucibles shall be of one-piece construction. Covers shall be flat, sunken in the center, and shall have an extension to serve as a handle. The sunken area in the center shall fit inside the crucible.