TRANSACTIONS OF SECTION I. 817 



■which possesses the property of being spontaneously inflammable. At the time 

 of its discovery in 1837 takodyl afforded the only knowii example of a liquid 

 ■which at once burst into flame on exposure to the air. The gas phosphoretted 

 hydrogen (which takes fire spontaneously) was known to chemists, and the solid 

 phosphorus -VN^as also known. Since the discovery of kakodyl a crowd of spon- 

 taneously inflammable substances liave come to light. Twelve years later on— 

 1848-1849 — the singular substances zinc methyl and zinc ethyl were discovered 

 in Bunsen's laboratory by the late Sir Edward Frankland ; and after another ten 

 years (also in Bunsen's laboratory) Wanklyn added to the list potassium ethyl, 

 sodium ethyl, lithium ethyl, calcium ethyl, and strontium ethyl. 



Spontaneous inflammability implies that the substance exerts chemical action 

 energetically and u-ith facility. 



Kakodyl of the year 1837 fired spontaneously, and also combined at once with 

 sulphur, chlorine, bromine, and iodine. But kakodyl did not decompose water. 

 Zinc ethyl (1847-48) not only combined with all the elements just mentioned, but 

 it was powerful enough to decompose water instantaneously. 



Sodium ethyl (1857-58) displayed energy enough to decompose carbonic acid 

 itself instantaneously, and at ordinary temperatures. 



4, The Physical Properties of Caseinogen Salts in Solution . 

 By W. A. Osborne, D.Sc. 



Vision. PyF. W. Edridge-Geeen, 3f.D., F.R.C.S. 



The hypothesis which I have brought forward for discussion at this meeting 

 is that light falling upon the retina liberates the visual purple from the rods and 

 a photograph is formed. The decomposition of the visual purple by light chemi- 

 cally stimulates the ends of the cones and a visual impulse is set up, which is con- 

 veyed through the optic nerve fibres to the brain. 1 assume that the visual impulses 

 caused by the diffbrent rays of light differ in character just as the rays of light 

 differ in wave length. Then in the impulse itself we have the physiological basis 

 of light, and in the quality of the impulse the physiological basis of colour. I 

 have assumed that the quality of the impulse is perceived by a special perceptive 

 centre within the power of perceiving diff'erences possessed by that centre or 

 portions of that centre. 



FRIDAY, SEPTEMBER 13. 

 The following Papers were read : — 



1, A Demonstration of Apparatus employed in Researches on the Subject of 

 Phonetics. By Professor J. G-. McKendrick, F.B.S. 



2. Restoration of Voluntary Movement after Alteration of the Nerve- 

 s%ipply by Nerve -crossing, or Anastomosis. By R. Kennedy, M,D. 



SATURDAY, SEPTEMBER 14. 

 The Section did not meet. 



