Allen J. Clark was the author of two papers published in the Journal of the Chemical, Metallurgical and Mining Society of South Africa during 1909-1910: "Precipitation from cyanide solutions by zinc shavings and dust: a comparison of results and costs" (Vol. 9, pp. 222-) and "Precipitating effects of substances containing various forms of carbon and cellulose on cyanide solutions containing gold and silver" (with Dr J.W. Sharwood*, Vol. 10, pp. 234-).
He may be the same person as Allan J. Clark who, with two others, was granted United States patent No. 2220212 in 1940 for an improved method of extracting gold and silver from ores by the cyanide process.