methods of lighting the mines without producing its explosion . 5 
I have analysed several specimens of the fire-damp in the 
laboratory of the Royal Institution ; the pure inflammable part 
was the same in all of them, but it was sometimes mixed with 
small quantities of atmospherical air, and in some instances 
with azote and carbonic acid. 
Of 6 specimens collected by Mr. Dunn from a blower in 
the Hepburn Colliery, by emptying bottles of water close to 
it, the purest contained only of atmospherical air, with no 
other contamination, and the most impure contained of 
atmospherical air ; so that this air was probably derived from 
the circumambient air of the mine. The weight of the purest 
specimen was for 100 cubical inches 19.5 grains. 
One measure of it required for its complete combustion by 
the electric spark nearly 2 measures of oxygene, and they 
formed nearly 1 measure of carbonic acid. 
Sulphur heated strongly, and repeatedly sublimed in a por- 
tion of it freed from oxygene by phosphorus, produced a con- 
siderable enlargement of its volume, sulphuretted hydrogene 
was formed, and charcoal precipitated; and it was found that 
the volume of the sulphuretted hydrogene produced, when it 
was absorbed by solution of potassa, was exactly double that 
of the fire-damp decomposed. 
It did not act upon chlorine in the cold ; but, when an elec- 
tric spark was passed through a mixture of 1 part of it with 
2 of chlorine, there was an explosion, with a diminution to 
less than and much charcoal was deposited. 
The analysis of specimens of gas sent to my friend John 
George Children, Esq. by Dr. Clanny, afforded me similar 
results; but they contained variable quantities of carbonic 
acid gas and azote. 
