The Etching Test for Small Amounts of Fluorides.

Abstract

The last example I give is the result on an alloy sent me by the Pittsburg Section of the American Chemical Society for analysis. The alloy contained, as reported to me after I had' sent in my report, the following: 4.98 to 5.02 per cent. copper, 14.70 per cent. antimony, and the balance tin. My report by this method was 14.73 per cent. antimony, the average of two determinations. NATIONAL LEAD Co., CINCINNATI BRANCH.

Microchemical Detection of Fluorides

“…As ordinarily performed, its sensitivity is not of a high order, various reports indicating the amount of fluoride required to produce a visible etching as ranging between 10 and 0.1 mg., with an average of about 0.5 mg. Greatly increased sensitivities were achieved by Woodman and Talbot (14,15) and later by Gautier and Clausmann (5), who with modified techniques were able to detect a few micrograms without, however, obtaining consistent results. Williams (IS), in an attempt to develop a quantitative method for the determination of minute amounts, was able to detect as little as 0.1 7, using flanged platinum distillation tubes embedded in a specially designed heating block.…”