Technical report. From Introduction : "For more than a century, methods employed in preparing calcium were based largely on electrowinning and the most successful were based on [Sir Humphrey] Davy's process. ... In general, the metal was of adequate quality for the industrial applications of the time, and although by 1940 some strides had been made in the purification of calcium, interests in the better grades of the metal were limited essentially to experimental work of academic concern."