Abstract

“THE DATA OF GEOCHEMISTRY”, by the late F. W. Clarke, is a mine of information on river waters, their variation with geological formation and Joly's ‘cyclic sodium’ transported in the air and brought down by rain. These phenomena are simply studied by measurements of electrical conductivity at 0° C. Thus C × 106 for Plymouth tap-water varied during 1923–24 from 25 to 28; the values found on July 7, 1923, and September 26, 1923, were 27 and 28—identical respectively with those of July 5, 1945, and September 19, 1945. The pH varied from 6·4 to 6·8 during the year. It was with some surprise that I found rain-water, collected at Downderry on the Cornish coast during a downpour on March 12, 1946, to have a conductivity 24, with pH. 6·6. Rain at Plymouth on March 13, 1946, had conductivity 55 and pH 4·0. During the night of September 19–20, 1946, rain at Antony, Cornwall, had conductivity 28, the typical September figure for Dartmoor water. Clean snow at Downderry on January 24, 1947, gave 44, and a Plymouth sample of January 25, 1947, gave 72 for conductivity. The latter was taken from the middle of the snow blanket and was, on thawing, surprisingly sooty. Plymouth rain of January 8, 1947, had conductivity 70, close to that of snow.