TI?K 



SOUTH AFRICAN JOURNAL 

 OF SCIENCE: 



COMPRISING TIIR REPORT OF THE :. 



SOUTH AFRICAN ASSOCIATION 



FOR THE 



ADVANCEMENT OF SCIENCE^^^STc^ 



1919- ^ ':ffr/?, 



RINGWILLIAMSTOWN. 



OFFICERS : 1919-1920. 



PRESIDENT. 



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



VICE-PRESIDENTS. 

 Prof. 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.A., F.C.S. 



HON. GENERAL SECRETARIES. S , • 



J. A. FooTE, F.G.S., F.E.T.S., Commercial Hi,s;h School, Auckland Park, Johannesburg 

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

 town. 



HON. GENERAL TREASURER. 

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

 . Technology, Johannesburg, 



ASSISTANT GENERAL SECRETARY. 



M. K, Carpenter, P.CBox 6894, Johannesburg. (Telefjraphir Address : "Science.") 



EDITOR OF TRANSACTIONS. 

 Dr. C. F. Juritz. 



VOL. XVi. SEPTEMBER, 1919. MO. 2. 



CAPETOWN. 

 PUBLISHED BY THE ASSOCIATION 



iyii> [Price 2s. 



