| 摘要 |
PURPOSE:To decide the genuineness of gold metal simply and rapidly, by a method wherein the electric conductivity and the density or the specific gravity of the gold ground metal containing 99% or more of gold are measured and measurement using ultrasonic waves is carried out while said gold metal is cut to observe visually the cut surfaces thereof to carry out comprehensive judgement. CONSTITUTION:The electric conductivity of gold metal is measured to distinguish gold metal or platinum alloy from other metal having electric conductivity lower than that of gold while the density or the specific gravity thereof is measured to distinguish an Au plated one with extremely low density while ultrasonic waves are applied to the gold metal to detect foreign matters existing therein from the reflected waves thereof and, by cutting the same, whether the foreign matters are air bubbles or voids or tungsten is determined from the presence and the absence of the foreign matters developed on the cut cross areas thereof thereby the genuineness of the gold metal is determined. |
