286 TRANSACTIONS OF SOCIETIES. 



to discuss plane waves on the basis of Maxwell's differential 

 equations in the Hertz-Heaviside form. The remaining half of 

 the book may be broadly divided into two sections ; the first of 

 these treats of the phenomena of reflection and refraction ; the 

 second deals with the optics of crystalline media. In the former the 

 author incidentally points out that the electromagnetic theory of 

 light has united in itself, as far at least as reflection and refraction 

 are concerned. Fresnel's and Neumann's theories, and the famous 

 quarrel about the direction of ?ethereal vibrations with respect to 

 the plane of polarisation has become an idle controversy. 



Apart from its undoubted value, from the purely scientific 

 point of view, Dr. Silberstein's little book constitutes an unfeigned 

 testimony to the far-seeing and deeply penetrating genius of that 

 brilliant and unassuming physicist who " enriched the inheritance 

 left by Newton and consolidated the work of Faradav."" 



TRANSACTIONS OF SOCIETIES. 



Chemical, Metalluk-ckal, and AIining Society of South Africa. — 

 Saturday, March i6th : G. Hildick-Sniith, B.Sc. President, in the chair. — 

 "The esfiniafion of injurious dust in mine air by the Kotse Konimeter'' : 

 J. Innes. A known quantity of air is caused to impinge at a higli 

 velocity through a fine nozzle on the surface of a glass slide thinly coated 

 witli vaseline: the dust content is deposited as a circular spot about i mm. 

 in diameter. The number of particles in a spot are subsequently counted 

 under a microscope. 



Saturday, April 20th : A. Whitby. Vice-President, in the chair. — " Fur- 

 ther notes on sandfilling of mines'": C. M. Greathead. An account of 

 minor alterations in the methods of sandfdling introduced during the last 

 five years, and of the development of methods put into practice in the 

 reclaiming of pillars, foot and hanging walls in portions of mines that 

 have been abandoned for many vears. 



Saturday, May i8th : H. S. Meyer, A.R.S.M., M.I.M.M.. Vice-Presi- 

 dent, in the chair. — " Ceiucutaliou process applied to minincj (Francois 

 System)": A. H Krynauiw. Cement grout is introduced, under 

 pressure, into minute fissures and cracks in rock strata. Several applica- 

 tions of the process were described, e.g., in connection v^'ith shaft-smking, 

 sealing of ferro-concrete shaft-lining or of open fissures, damming back of 

 water near open ground, rendering underground dams watertight, rectify- 

 ing defective boreholes, and rendering foundations of dam walls 

 impervious. 



Saturday, June 22nd : H. A. White, Vice-President, in the chair. — 

 "The estimation of oxygen in working cyanide solutions" :H. A. White. 

 To the solution is added Vjo gram of pyrogallol and i cc. of zN-NaOH. 

 and the resulting liquid is compared colorimetrically with a series of 

 standard solutions. — ''Note on the removal of a vertical shaft pillar^': J. 

 Chilton. A description of the operation of removing a large shaft pillar 

 in the Village Main Reef Gold Mine, which had on two occasions become 

 damaged in consequence of severe earth tremors. 



Saturdaj^ September 21st: H. S. Meyer, A.R.S.M., M.I.M.M.. Presi- 

 dent, in the chair. — Presidential address : H. S. Meyer. The address 

 dealt with recent progress in mining and metallurgy in South Africa. 



Saturday. November T6th : H. S. Meyer, A.R.S.M., M.I.M.M., Presi- 

 dent, in the chair. — " Notes on the footwall Ijeds of the far east Rand 

 reef": L. W. Macer. The stratigraphy of the far east Rand is assumed 

 to be simplified by the existence of the "slate" footwall. which is so 

 easily recognised that it constitutes a reliable indicator for the payable 

 reef of this area. The author pointed out that this deposit is of a variable 

 nature, both petrologically and in its mode of occurrence, and is not so 

 readily distinguished as is generally supposed. 



