222 Annals of the Philosophical Club 



Nov. 25th, sigth meeting. In regard to Mr. Galton's 

 instrument, 1 Professor Tyndall referred to M. Topler's 

 experiments on the intermittent flashing of a singing flame, 

 as one of a class of phenomena to which that mode of observa- 

 tion might be applied, and Professor M. Foster thought it 

 might be used in connexion with the velocity of light. 



Dec. I4th, 32oth meeting. Sir H. Lefroy stated that he 

 had known many instances of lightning striking buildings 

 on the Bermudas, though the area of the islands was only 

 about 12,400 acres, and asked whether anything in the 

 condition of oceanic islands could explain this frequency. 

 Professor Stokes said that ascending currents of air, charged 

 with moisture, which is condensed on their rising high 

 enough, are favourable to thunderstorms. As the Ber- 

 mudas, in a hot climate, are surrounded by ocean, and have 

 low and warm surfaces, they would cause ascending currents 

 in the moisture-charged air that passed over them, which, 

 though not large enough to cause great tempests, would 

 suffice to produce many small thunderstorms. 



Professor Dewar described the results of his recent experi- 

 ments on the amount of hydrocarbon acetylene produced r 

 when different forms of electric discharge pass between 

 graphite poles in an atmosphere of hydrogen. The most 

 interesting fact was the increase in the partial pressure of 

 the acetylene in the resulting mixture as the initial pressure 

 of the hydrogen is diminished. Thus, at the pressure of 

 the atmosphere, the acetylene amounts to 12 per cent, by 

 volume, but when the pressure in the hydrogen is only 

 one-eighth of an atmosphere, it rises to 22 per cent. This 

 may be called a true manufacture of illuminating gas 

 by electricity. Benzol is always found mixed with the 

 acetylene. 



Professor Stokes asked whether any substance capable 

 of producing changes in the plane of polarization had yet 

 been artificially produced. Professor Dewar replied in 

 the affirmative, for racemic acid can be obtained from 

 glycoxalic and succinic acids, both of which have been 



1 See Minutes of June I5th. 



