210 TKAXSAfTlONS OF SOCIETIES. 



ycincse-silz'cr f^rabU'iii " : \\ . Neal. An account oi pro.yrcss made in 

 solving the difficulties encountered in the treatment of rebellious man- 

 ganese-silver ores. 



Saturday, October jist: Prof. J. A. Wilkinson, .M.A., F-C.S., Presi- 

 dent, in the chair. — " 'J'lic hardening end annealiii^ of metals'': Prof. T. 

 Turner. The effects produced ui)t>n the ])roperties of metals and alloys 

 by cold working, such as hammi-ring or drawing, were discussed. The 

 nature of tlie hardening which takes place under such treatment may be 

 grasped by assuming that in a crystalline metal or alloy shearing results 

 in the formation of a him of amorphous material, closely allied in its pro- 

 perties to those of a surface him in a liquid, and that annealing releases 

 the state of strain existing in tliese thin lilms. thus leading to an increase 

 of density, and permits of recrystallisation. — " Testing the strength of 

 explosives" : J. A. Campbell. A short account of the types of apparatus 

 used for testing the streiigtli of explosives, and of the methods of deter- 

 mining their sensitiveness and rate of detonation. 



Saturday, November r8th : Prof. J. .\. Wilkinson. :\1..\.. F.C.S.. Pre- 

 sident, in the chair. — " \' eutralisation effect of ash on aeid-sand in stopc- 

 filling:" C. Toombs. Sand from a dump which had been used for stope- 

 filling was subsequently found to cause trouble by reason of its extreme 

 acidity. It was tlierefore decided tf) mix ordinary ash from the ash 

 dumps with the acid sand, and to send this mixture underground as 

 filler. The ash usually contains from 25tb. to 4olb. of free calcium o.xide 

 per ton. and it was found tliat 2,200 tons of ash and 13 tons of lime were 

 needed to neutralise the acid in 22,000 tons of sand. — "Flotation iinucn- 

 tration experiments on a Transvaal Gold ore": F. Wartenweiler. 

 An account of an investigation having for its object the maximum reco- 

 very of gold from an arseno-pyrttic gold ore developed below the oxidised 

 zone of mine working at Piarberton. — " Ore treatment at the Falcon Mine. 

 Rhodesia " : H. R. Adam. The mine is situated at Umvuma. 160 miles 

 from Bulawayo, and its monthly output is about 6oo.ooolb. of blister 

 copper, 3,000 oz. of gold and 6,000 oz. of silver. An outline was given of 

 the milling and smelting processes employed at the mine. 



South Afkic.vn I.xstitutk ok Ei,i:c:tkicai. Engineeks. — 'I'hursday. 

 September 21st: Prof. W. I'.uchanan. M.1.I'].E., President, in the chair. — 

 " The main szvitch-boaru of the Johannesburg Municipal Electric supply 

 system": Major J. 11. Dobson. The switcliboard differs widely from any 

 in u.se for mining t)n the Witw.itersrand. It provides for three require- 

 ments : direct current power at 600 volts for traction ; three-wire direct 

 current at 460 and 230 volts in the Inner Area; and a 3,000 volt alternating 

 current supply for the suburl)s. All erection work connected with the 

 switchboard was carrietl out by the Municipal Council's employes. A 

 noticeable feature of the whole switchboard is the large margin of safety 

 in connection with tlie insulation: |)orcelain is used throughout, and the 

 size of all insulators is at least doulile that usually supplied by makers 

 for a given pressure. 



XEW BOOKS. 



Plaatje, S. T.—" Native life in South Africa before and since the Euro- 

 pean War and the Boer Rebellion." Post 8vo. pp. 352. Ports. 

 London; P. S. King & Son. 1016. 160.7. 3s. 6d. 



Rayner, W. S., and W. W. O'Shaughnessy. — " Hoiv Botha and 

 ■^fniils conquered (Jerman South-West Africa." pp. 21H). London; 

 .'^impkiii, Marshall & Co., h)i6. r6oz. 2S. 



Evans, Maurice S.— ' Black and While in the Southern States: 

 A .S'tudy of the Race problem in the United States from a South 

 .Ifrican f^oint of viciv." London: Longmans. Green & Co. 1915. 



Theal, G. McCall.— " flistorv of South Africa, from 1795 to 1872.'" 

 Vol. 3. i>p. xvii. 496. 3 ciiarts. London: Mien & Umvin. 1016. 

 7s. 6(1. 



Robinson, J. P. Kay — ■ ll'iti: Rotha's .Army." London: .\llen & 

 Unwin. iui6. 3s. 6d. 



