136 



O. U. VONWILLER. 



NOTES ON the ELASTIC PROPERTIES OF SELENIUM. 



By O. U. VONWILLER, B.Bc. 



[Read before the Royal Society of N.S. Wales, October 1, 19l9.~\ 



In 1916 the writer performed some experiments primarily 

 with the object of determining elastic constantsof selenium. 

 The investigation was not carried far before it had to be 

 given up, mainly on account of lack of time, but some 

 qualitative results were obtained which appear to be of 

 sufficient interest to be recorded; among these is a light 

 effect not noticed before. 



Thin threads of vitreous selenium were prepared by 

 dipping the end of a glass rod into molten selenium and 

 withdrawing it fairly rapidly. It was found that, unless 

 the temperature of the liquid were too high — in which case 

 threads could not be drawn on account of the great fluidity 

 of the substance — long threads were produced without 

 difficulty; these invariably contained numerous inequalities 

 in thickness, but usually it was possible to obtain several 

 pieces 10 centimetres or more in length, of fairly uniform 

 section, the diameter being generally about 0*04 centimetre. 

 These threads seemed to consist wholly of vitreous selenium 

 no trace of the crystalline modification being visible. 



In endeavouring to determine Young's modulus, methods 

 of bending were first used; in some cases a thread was 

 supported near its ends and loaded in the middle by means 

 of bent pieces of thin wire placed on a light wire hook 

 hanging at the central point, while in others one end of the 

 thread was held between a pair of metal jaws lined with 

 paper to prevent ciushing, and loaded by a metal rider 

 placed near the free end, the depression, on loading, of the 



