68 Gold Leaf and Absorption Spectrum of Gold. [May 22, 



y/f 



Therefore, when 6 is not small, ^ vanishes to the first order at, 



Gpr^a, 



least, so that there is no first order effect at a point on the surface of 

 the sphere which is at a finite angular distance from the oscillator. 



" On the Structure of Gold Leaf aud the Absorption Spectrum of 

 Gold." By J. W. MALLET, F.RS., Professor of Chemistry in 

 the University of Virginia. Received May 22, Read June 11 , 

 1903. 



(Abstract.) 



Attention is drawn to numerous irregularly distributed black lines 

 which are to be seen in gold leaf examined with the microscope by 

 transmitted light. These lines are shown to depend on the presence 

 of minute wires or threads of the metal, unconnected with its crystal 

 line structure, but produced in the process of gold beating by the 

 stretching, along lines of weakness, of the animal membrane between 

 sheets of which the gold is placed, thus developing minute trough-like 

 wrinkles into which the soft metal is forced. 



The results are given of an examination of the absorption spectrum 

 in the visible, ultra-violet and infra-red regions of metallic gold in 

 a finely divided condition, as found' in gold-coloured glass, and as 

 reduced from dilute aqueous solutions of its salts. 



