PROCEEDINGS OF THE SOCIETY. 397 



Mr. F. Shilling-ton Scales read a number of extracts from a paper 

 contributed by Mr. James Strachan, " On Dendritic Growths of Copper 

 Oxide on Paper," the subject being illustrated by a large number of 

 examples exhibited under Microscopes in the room. Lantern slides of 

 some of these were subsequently shown upon the screen. 



Mr. Strachan verified previous investigations showing that these 

 dendrites originated in minute particles of copper, their branching 

 being due to the direction of the fibres in the paper, and showed further 

 that they were not peculiar to any particular kind of fibre, that they 

 formed a coating outside and not inside the fibre, that they were found 

 in quite recent papers, and that they might be formed in as short a 

 time as twelve months. He advanced various suggestions with regard 

 to the chemical process which took place. 



Mr. Scales beiug called upon by the Chairman for an expression of 

 his own opinion on the subject, said that he should not wish to indorse 

 all the theories which Mr. Strachan had put forward in this very 

 interesting paper, but there was no doubt he was right as to the fact 

 that these forms arose from the oxidation of particles of copper derived 

 from portions of the machinery during the process of manufacture of 

 the paper that they branched along the fibres of the paper, and that 

 this process took a much shorter time than had hitherto been thought 

 possible, but when he came to the reasons why they branched out in this 

 remarkable manner, and the chemical changes which caused them to do 

 this, he was getting upon rather more controversial ground. The copper 

 must necessarily have an intermediate stage of solution of some kind, 

 but what was the exact nature of the process by which it was dissolved 

 and re-crystallised was not yet set beyond question. 



The Chairman said they were much indebted to Mr. Scales for bring- 

 ing the subject before them in the absence of the author of the paper. 



The thanks of the Society were unanimously voted to Mr. Strachan 

 for his paper, and to Mr. Scales for reading it. 



Mr. F. Enock then gave a very interesting exhibition of lantern 

 slides in illustration of his remarks on " Nature's Protection of Insect 

 Life " — all the slides having been taken by the Sanger-Shepherd three- 

 colour process. Mr. Enock prefaced his description of the pictures 

 by a brief accouut of the process which he had employed in their pro- 

 duction, by transferring the red and yellow prints to the blue plate, so 

 as to avoid the necessity of transmitting the light of the lantern through 

 the thickness of three films — with the result that a much brighter 

 picture was produced without in any way impairing the fidelity of the 

 coloration. The difficulties experienced in taking photographs of living 

 subjects, which were likely to move during the time needed for three 

 exposures, were also mentioned. The series exhibited comprised a 

 number of illustrations of so-called mimicry on the part of moths and 

 caterpillars, some of which had settled themselves on bark and other 

 objects so nearly of the same colour as themselves that it was extremely 

 difficult to determine their whereabouts. The exhibition concluded with 



