of
rainfall. It is curious to note, also, that there is a marked
difference in the rapidity of disintegration of the blue ground in each
of the four mines. The blue from Kimberley mine becomes well pulverized
in six months with heavy rains in the summer season, while the De Beers
blue requires double that time. The longer the exposure, the more
complete the pulverization, and the better for washing. The long
continuance of droughts, which are of frequent occurrence, causes very
costly delay. During a period of more than eight months in 1897 there
was not sufficient rain to wet the blue ground. The lack of rain water
was offset, in a measure, by artificial means ; but as the blue ground
upon De Beers and Kimberley floors covers 2000 acres of land,
