THE 



SOUTH AFRICAN JOURNAL 

 OF SCIENCE: 



COMPRISING THE REPORT OF THE 



SOUTH AFRICAN ASSOCIATION 



FOR THE 



ADVANCEMENT OF SCIENCE. 



1919. 



RINGWILLIAMSTOWN. 



OFFICERS: 1919-1920. . ^ 



PRESIDENT. ' • ' 



I. B. Pole Evans, M.A., D.Sc, F.L.S. 



VICE-PRESIDENTS. 

 P'"°J- J- W. Bews, M.A., D.Sc. Prof. R. Le.slie, M.A., F S S 



Prof. J. E. DuERDEN, M.Sc, Ph.D., A.R.C.S. Prof. J. A. Wilkinson, M.X, F.C.S. 



HON. GENERAL SECRETARIES. 



J. A FooTE, F.G.S., F.E.I.S.. Commercial High School. Johannesburg 

 C. F. JURiTz, M.A., D.Sc, F.I.C., Agricultural Chemical Research Laboratory Cape- 

 town. J'. ^ FV. 



HON. GENERAL TREASURER. 

 Prof. C. E. Moss, M.A., D.Sc F.L.S.. F.R.G.S.. South African School of Mines and 



Technology. Johanneslntrg. 



ASSISTANT GENERAL SECRETARY. 

 M. K. Carpenter. P.O. Box 6894, Johannesburg. (Telegraphic Address : "Science.") 



EDITOR OF JOURNAL. 

 FiiOF. H. B. Fantham, M.A.. D.Sc. S.A. School of Mines, P.O. Box 1176. 



Johannesburg. 



VOL XVI. OCT.-DEC, 1919. NO. 3. 



JOHA.VXESBURG. 

 PUBLISHED BY THE ASSOCIATION, 



1919. 



[Price 6s. 



