252 Annals of the Philosophical Club 



A bright zinc plate, however, would not only produce a 

 complete picture of markings on it, when laid on a sensitive 

 plate, but this action also occurred through considerable 

 distances, and even if such substances as celluloid, gelatine, 

 gutta-percha tissue, goldbeater's skin, vegetable or real 

 parchment were interposed between the two plates. Other 

 metals and their alloys, such as mercury, magnesium, 

 cadmium, nickel, cobalt, aluminium, lead, tin, antimony, 

 pewter, or fusible metal, acted in the same way. Copal and 

 some other varnishes produced similar effects, and a picture 

 of such a thing as a skeleton leaf could be obtained by 

 putting it between a photographic plate and a sheet of 

 zinc, or piece of glass, covered with copal, but pure paper, 

 after being soaked in a solution of certain salts, prevented 

 the passage of any such action. Wood also was similarly 

 active, and a good picture was obtained by laying a piece 

 of it on a photographic plate. Printers' ink in many cases 

 had the same effect, and remarkably clean dark pictures 

 came from placing either the blank or the inked side of a 

 page of print on such a plate. Pill boxes, in which some of 

 the uranium salts had been kept, were found to have a 

 similar effect, for they were usually made of straw-board 

 covered with white paper, and the former could act, though 

 to a less extent, like zinc and copal. 



1898. Jan. 2oth, 455th meeting. Professor Anderson 

 Stuart * (a guest), from the University of Sydney (Australia), 

 gave an account of that University. It was incorporated 

 by Royal Charter in 1850, and at the present time received 

 from the State an annual subsidy of 12,000, besides other 

 pecuniary aid. Its buildings were well situated, and its 

 students numbered about 600, including 80 women. No 

 distinction was made between the sexes, and no difficulties 



1 Sir Thomas Anderson Stuart was born at Dumfries on June aoth, 1856, 

 and, after taking the M.D. degree with special distinction at the University 

 of Edinburgh, became Professor of Physiology in the University of Sydney. 

 There he has been for not a few years an energetic worker in medical and 

 allied scientific subjects, and was a leader in organizing the three expe- 

 ditions for making a deep boring into the atoll of Funafuti in the Eliice 

 Islands. He was knighted in 1914. 



