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II. An account of an invention for giving light in explosive mix- 
tures of fire-damp in coal mines, by consuming the fire-damp. 
By Sir Humphry Davy, LL. D. F. R. S. V. P. R. I. 
Read January 11, 1816. 
1 have already had the honor of communicating to the Royal 
Society an account of a safe light, which becomes extinguished 
when introduced into very explosive mixtures of fire-damp ; 
in this communication I shall describe a light which will burn 
in any explosive mixture of fire-damp, and the light of which 
arises from the combustion of the fire-damp itself. 
The invention consists in covering or surrounding the flame 
of a lamp or candle by a wire sieve ; the coarsest that I have 
tried with perfect safety contained 625 apertures in a square 
inch, and the wire was of an inch in thickness, the finest 
6400 apertures in a square inch, and the wire was of an 
inch in diameter. 
When a lighted lamp or candle screwed into a ring sol- 
dered to a cylinder of wire gauze, having no apertures, except 
those of the gauze or safe apertures, is introduced into the 
most explosive mixture of carburetted hydrogene and air, the 
cylinder becomes filled with a bright flame, and this flame 
continues to burn as long as the mixture is explosive. When 
the carburetted hydrogene is to the air as 1 to 12, the flame 
of the wick appears within the flame of the fire-damp ; when 
the proportion is as high as 1 to 7, the flame of the wick 
disappears. 
