101 
Ordinary Meeting, February 21st, 1865. 
R. Angus Smith, Ph.D., F.R.S., &c., President, in 
the Chair. 
Mr. Thomas Worthington was elected an Ordinary Member 
of the Society. 
M. Breguet, of Paris, exhibited and explained the con- 
struction of Dumas’ lamp for use in coal mines, the principle 
of which consists in the employment of the light from a 
Geissler’s vacuum tube, excited by a small RuhmkorfFs 
induction coil. 
Professor Roscoe stated that he had very frequently been 
asked for information respecting the mode of preparing the 
sealed bulbs, containing exactly equal volumes of chlorine 
and hydrogen gases, which he employed for exhibiting the 
chemical combination of these gases effected by the action of 
light, and as the successful preparation of these bulbs depends 
upon exactly observing certain minute conditions, he ventured 
to submit the following particulars to the Society. The 
apparatus needed, consists of a stout tube or narrow bottle of 
about 120 cubic centimetres capacity, fitted with a caoutchouc 
stopper with three holes bored through it. Into one of 
these holes a vent gas delivery tube passes, on to which three 
small wash bulbs are blown ; into the other two holes are 
inserted the rounded ends of two lengths of the gas carbon, 
Proceedings Lit. & Phil. Society— Yol. IY.— No. 11.— Session 1861-5. 
