Is Some new Researches on Flame. 
gauze at the common temperature, the gauze cools each portion 
of the elastic matter that passes through it, so as to reduce its 
temperature below that degree at which it is lnminous, and the 
diminution of temperature must be proportional to the smallness 
of the mesh and the mass of the metal. The power of a metal- 
lic or other tissue to prevent explosion, will depend upon the 
heat required to produce the combustion as compared with that 
acquired by the tissue; and the flame of the most inflammable 
substances, and of those that produce most heat in combustion, 
will pass through a metallic tissue that will interrupt the flame 
of less inflammable substances, or those that produce little heat 
in combustion. Or the tissue being the same, and impermeable 
to all flames at common temperatures, the flames of the most 
combustible substances, and of those which produce most heat,will 
most readily pass through it when it is heated, and each will 
pass through it at a different degree of temperature. In short, 
all the circumstances which apply to the effect of cooling mix- 
tures upon flame, will apply to cooling perforated surfaces. Thus, 
the flame of phosphuretted hydrogen at common temperatures, 
will pass through a tissue sufficiently large not to he immediately 
choked up by the phosphoric acid formed, and the phosphorus 
deposited*. A tissue of 100 apertures to the square inch, made 
of wire of 1-60th, will at common temperatures intercept the 
flame of a spirit-lamp but not that of hydrogen; and when 
strongly heated, it will no longer arrest the flame of the spirit- 
lamp. A tissue which will not interrupt the flame of hydrogen 
when red hot, will still intercept that of olefiant gas; and a heated 
tissue which would communicate explosion from a mixture of 
olefiant gas and air, will stop an explosion from a mixture of 
fire-damp. or carburetted hydrogen. 
The ratio of the combustibility of the different gaseous matters 
is likewise to a certain extent as the masses of heated matter 
required to inflame themt. Thus an iron wire of 1-40th of an 
inch heated cherry red, will not inflame olefiant gas, but it will 
inflame hydrogen gas; and a wire of 1-Sth, heated to the same 
degree, will inflame olefiant gas; but a wire of 1-500dth must 
be heated to whiteness to inflame hydrogen, though at a low red 
heat it will inflame bi-phosphuretted gas; but wire of 1-40th 
* Ifa tissue containing above 700 apertures to the square inch be held 
over the flame of phosphorus or phosphuretted hydrogen, it does not trans- 
mit the flame till it is sufficiently heated to enable the phosphorus to pass 
through it in vapour. Phosphuretted hydrogen is decomposed in flame, 
and acts exactly like phosphorus. :3 
+ It appeared to me in these experiments, that the worst conducting and 
best radiating substances required to be heated higher for equal masses to . 
produce the same effect upon the gases: thus, red hot charcoal had evi- 
dently less power of inflammation than red hot iron. 
heated 
