GOLD EXTRACTION METHODS. I03 



after long- exposure to the atmosphere. On the other hand, 

 when using- sand directly from the treatment vats, the cyanide 

 present must be effectually destroyed in order to avoid genera- 

 tion of prussic acid gas in the underground workings. It is 

 fortunate that several methods of performing this work are 

 now available. Dr. Moir and Mr. Gray have suggested the 

 use of sulphate of iron and an alkali, and if this method is 

 found sufficiently safe in practice it will cost an insignificant 

 amount for the chemicals necessary. At the Simmer and 

 Jack permang-anate of potash has been found to completely 

 destroy the cyanide, so far as even delicate indicators can 

 determine, at a cost of about one penny per ton, and experi- 

 ments with an alkaline solution of bleaching powder, which 

 promises even lower cost, are now being made. 



It is certain that by some of the means suggested above it is 

 perfectly feasible to solve the question of direct return of the 

 sand to the mine, but at the present moment there is little 

 hope of rendering the slime available for underground support, 

 and though the future may see the disappearance of the dismal, 

 dusty sand dump, the permanent presence of the unsightly 

 slime-dam seems an assured feature of the landscape of the 

 Witwatersrand. 



Since so little progress, except in details, has been made 

 in the chemical side of our work it is much to be deplored that 

 we have no University in this State where the research work, 

 so necessary for imparting life to the dull routine of teaching, 

 and so urgent for a correct understanding and development of 

 the practice of gold solution and recovery, can be carried on; 

 and it is to be hoped that this defect may in a short time be 

 remedied. 



In conclusion, the interesting observation may be made that 

 in no period of its history in the past has so long a vista been 

 possible as now of the future life of these, the most important 

 goldfields vet discovered in this world. 



THE DARWIN MEDAL. — At the anniversary meeting of 

 the Royal Society, which was held on the 30th November, the 

 President, Sir Archibald Geikie, K.C.B., D.Sc. made the fol- 

 lowing reference to the 1910 biennial award of the Darwin 

 Silver Medal. 



" To Mr. Roland Trimen, who was for many years curator 

 of the South African Museum in Cape Town, the Darwin 

 medal has been awarded. His official position, and the duties 

 it involved, enabled him to do admirable work in African 

 zoology. His name will always stand with those of Bates and 

 Wallace in the establishment and illustration of the theory of 

 mimicry. In addition to his researches on that subject, he has 

 done admirable systematic work, his descriptions of insects, 

 especially the Lepidoptcra rhopaloccra, being models of 

 accuracy and literary stvle. He, furthermore, rendered the 

 greatest assistance to Charles Darwin, especially in his work 

 o'fi orchids — as5(istance the high value of which is acknow- 

 ledged in a long series of that great naturalist's published. 

 letters." 



