233 
Ordinary Meeting, February 9th, 1864. 
E. W. Binney, F.R.S., F.G.S., President, in the Chair. 
George Harris, Esq., Barrister-at-Law, was elected an 
Ordinary Member. 
Professor Roscoe. exhibited the light emitted by burning a 
portion of a fine specimen of pure magnesium wire 1 mm. in 
diameter and 10 feet long, which had been manufac- 
tured by Mr. Sondstadt. Professor Roscoe remarked 
that it afforded him great pleasure to be able to state 
that a suggestion made by Professor Bunsen and himself 
in their photochemical researches, and printed in the Philo- 
sophical Transactions for 1859, page 922, was about to be 
practically adopted. Mr. Sondstadt is now commencing to 
manufacture the metal magnesium on the large scale, and 
the first important application of the metal is the employ- 
ment of burning magnesium wire as an illuminating agent, 
especially for photographic purposes. In the researches- above 
mentioned Professor Bunsen and the speaker had examined 
the photaehemical action of the sun compared with that of a 
terrestrial source of light, and for the purpose of this com- 
parison they chose the light evolved by the combustion of 
magnesium wire. They showed that a burning surface of 
magnesium wire which, seen from a point at the sea’s level, 
has an apparent magnitude equal to that of the sun, effects 
on that point the same chemical action as the sun would 
do when shining from a cloudless sky at a height of 
9° 53' above the horizon. On comparing the chemical with 
Proceedings— Lit. & Phil. Society— No. 12 .— Session 1863-64 
