385 



a,ctivity. Tlie results of experiments mentioned at that 

 meeting, which had been commenced to determine the matter, 

 were tabled. Samples of glass-headed pins, the glass of which 

 presumably contained manganese, had been well protected by 

 black paper from any ultra-violet radiation which mi^ht come 

 from the incandescent filament in the "Coolidge" tube. Each 

 pin so protected was fixed by a similar pin to the inside of 

 the box containing a ''Coolidge" tube in frequent use. 

 Results show that the amethystine colouration produced is 

 equal in both pins. As one pin was protected from ultra- 

 violet radiation, it is obvious that its colour change is due to 

 X-ray radiation as apart from ultra-violet radiation. 



A. R. Riddle. 

 Evening Meeting, May 13, 1920. 



Radio=active Photog^raph of Autunite. 



Three specimens of Autunite (calcium uranium phos- 

 phate) from Mount Painter were placed on an Ilford X-ray 

 plate which had been wrapped in two thicknesses of light-proof 

 paper. Tliey occupied this position for 48 hours, when the 

 plate was developed. The tabled photograph demonstrates 

 the radio-active nature of the mineral, the results beine some- 

 what akin to the photograph made by Sir William Crookes 

 ■of pitch-blende. Tlie energy which affected the X-ray plate 

 was derived entirely from the autunite specimens. 



A. R. Riddle. 

 Evening Meeting, November 13, 1919. 



Radiog^raph of a Skull of an Australian Aborigine. 



A lateral radiograph was exhibited, made from the living 

 subject, of the head of an Australian aborigine. The develop- 

 ment of the frontal region generally, the frontal sinus and 

 the very thick developm.ent of bony tissue anterior to it, 

 together with the development of the lower mandible, 

 especially the ascending ramus, were among the most inter- 

 esting points of difference compared with the skull of the 

 normal white. 



A. R. Riddle. 



Evening Meeting, April 8, 1920. 



