When white lead is corroded from metallic (pig) lead that contains an appreciable percentage of copper, the presence of the latter in the dry white lead can be readily determined by a very simple test. A small portion of lead is rubbed up in bleached linseed or poppy seed oil until fine; that is, free of lumps, to a paste, and then reduced to liquid consistency with spirits of turpentine and a portion of this placed in a three-quarter inch by six inch test tube and set aside to settle. If copper is present the turpentine will show a more or less greenish color, otherwise it will be clear. Should the turpentine, however, show a discoloration similar to rust it indicates the presence of iron in the white lead.