262 
Proceedings of Royal Society of Edinburgh. [sess. 
Electrification of Air by Flame. By Sir William 
Thomson. 
(Read July 15, 1889.) 
In continuation of experiments on the electricity of air within 
doors, which I made twenty-seven years ago, and which are described 
in §§ 296-300 of my Electrostatics and Magnetism, a series of ob- 
servations was commenced under my instructions at the end of April 
last, within the Natural Philosophy Class Room and Laboratory, 
the Bute Hall, the University Tower, and other places inside and 
outside the buildings of Glasgow University, by Mr Magnus Maclean, 
official assistant to the Professor of Natural Philosophy, and Mr 
Goto of Tokio, Japan, for the purpose of endeavouring to find a 
relation between the electrification of air within a building and the 
atmospheric potential in its neighbourhood outside ; and of finding 
causes which produced or changed the electrification of any given 
mass of air. 
A large number of series of observations have been made by Mr 
Maclean and Mr Goto on the potentials of water-dropping collectors 
within the building, and at different points outside the building. 
Hitherto no definite relation has been discovered between the ex- 
ternal potential and the potential at different points within large 
enclosures, such as the Bute Hall and smaller rooms of the Uni- 
versity Buildings. The weather has been for the most part very 
settled and the external potential almost always positive in all posi- 
tions from a few feet above the ground to the top of the University 
Tower; while the potential within doors here, in the new University 
Buildings, on the top of Gilmour Hill, just as in the old College, 
down in the densest part of Glasgow, was always negative except 
sometimes in the Natural Philosophy Lecture Room and Apparatus 
Room, where there were considerable disturbances, undoubtedly due 
to the electric light wiring. In one ordinarily unused room (the 
Physical Apparatus Museum) 31^ feet long by 24 feet broad and 
about 20 feet high, practically quite free from any sensible dis- 
turbance by electric light wires, or by electrical operations being 
performed in the Laboratory, a remarkable result has been observed 
within the past fortnight. The electric potential of a water-dropper 
