147 
Then follows a notice on the Quebracho wood of South 
America, from which Mr. Arnaudon has produced a fine 
yellow on wool. 
Violet Palisander wood (Madagascar), contains a violet 
coloring matter which differs from that of the bois d’amarante, 
and may be fixed in the same manner as the coloring matter 
of Logwood. 
In a last notice on the coloration of the solution of guaiac 
resin, the Author shows by experiments that it is produced 
only by the action of oxygen. 
From general considerations deducted from comparative 
experiments set down by him in tabular form, Mr. Arnaudon 
concludes that, with our present chemical knowledge, general 
laws for the production of organic coloring matters cannot 
be laid down. 
A Paper by Mr. John Smith, M.A., was read by his 
brother. Dr. R. A. Smith, entitled “ On the cause of Colour 
and the Theory of Light.” 
The Author, in attempting to explain certain natural 
phenomena, could not satisfy himself by applying the 
principles of either theory of light, and said that many natural 
phenomena indicated beats or vibrations in the luminous 
ether very different from what science taught. That is, that 
there were greater intervals between them than Newton 
had demonstrated and scientific men believed. He therefore 
endeavoured to contrive experiments by which he would be 
able to make as many revolutions or beats in a second as he 
considered the effective vibrations of light were repeated in a 
second of time, and argued that by certain contrivances to 
produce light and shade in alternate vibrations he should 
produce colour. A series of experiments was subsequently 
undertaken, which led to the conclusion that varieties of 
colour are produced by pulsations of light and intervals of 
shadow in definite proportions for each shade of colour. That 
