NATIONAL MUSEUM OF THE ORANGE RIVER COLONY. 363 



of coins represents the decent figure of about 2,000, but a large 

 amount cannot be exhibited. And now, last but not least, I 

 beg to mention our collection of Mammals, Horns, Skulls, 

 Skeletons, etc. It is our endeavour to acquire as many speci- 

 mens of South African animals as possible, species which are 

 threatened with extermination through wholesale slaughter by 

 all kinds of creatures, human and otherwise. Here again we are 

 obstructed by the want of space, so that our large game like 

 Rhinoceros, Elephants and Hippotamus cannot be repre- 

 sented. More than 20 skins of large Antelopes had to be 

 stored away and cannot be stuffed. 



HELIUM IN THE GERMAN POTASH DEPOSITS.— 



For the last six years there has been a continuous evolution of 

 inflammable gas from one of the potash workings at Leopolds- 

 hall. The occurrence is described by E. Erdmann in a recent 

 issue of Berichte. He there states that the gas contains 83*6 

 per cent, of hydrogen and 4*4 per cent, of methane. Nearly 

 I per cent, of the residual gas after the removal of the hydrogen 

 consists of helium and neon, the former largely pre- 

 ponderating. These two together constitute about "17 per cent, 

 of the original gas as it issues from the blower. The author 

 ascribes the presence of helium to the degradation of radium, 

 salts of which were originally present in the waters of the sea 

 from which the potash salts were deposited. The existence 

 of hydrogen under these conditions he considers to be due to 

 radio-active decomposition of the water, the disappearance of 

 the oxygen simultaneously set free being, in his opinion, 

 accounted for by the oxidation of the ferrous into ferric salts. 



STERILISATION OF URBAN WATER SUPPLIES.— 



An apparatus has been constructed by Henri, Helbronner, and 

 de Recklinghausen for the sterilisation of large quantities of 

 water by means of ultra-violet rays, and a description of their 

 process is given by the authors in Comptcs Reudiis, vol. 150. 

 pp. 932-934. They claim for it the capability of sterilising a 

 quantity of 125 cubic metres of water per hour — sufficient for 

 the needs of a town of 20,000 inhabitants. The water is made 

 to flow through a zig-zag pipe of four bends, in each of which 

 bends a Westinghouse Cooper-Hewitt lamp, provided with a 

 reflector, is suspended from a float in such a manner as to 

 remain 2 centimetres below the water level. When water in- 

 fected with Bacillus coli was made to flow through the pipe 

 at the rate of 36 cubic metres per hour, complete sterilisation 

 was effected by the time the water had passed the second lamp. 



