On Spontaneous Inflammations . 
S. Sulphurized and Phosphorized Hydrogen Gas . 
Subterranean fires and volcanoes are generally ascri- 
bed to the decomposition of pyrites and metallic sulphu- 
rets buried in the bosom of the earth. These pyritous 
masses are decomposed by the contact and concurrence 
of water and air, and the decomposition is always ac- 
companied with a great expansion of caloric, and a dis- 
engagement of a highly inflammable gas called sulphur- 
ized hydrogen gas. This gas inflames at an elevated 
temperature, and may communicate inflammation to the 
sulphur of pyrites, to coals, and other bituminous matters 
with which they are in general accompanied. 
Similar inflammations are observed sometimes in the 
neighbourhood of coal mines. In working coal mines.* 
veins and insulated pieces of pyrites are often found : as 
pyrites always communicates a bad quality to coal, the 
miners generally lay it aside and take it out of the pit. 
If these heaps of pyrites, intermixed with coal, are then 
exposed to the alternate action of the sun and rain, they 
become heated, and inflame. Great care must therefore 
be taken that such heaps of pyrites be removed from all 
combustible bodies to which they would necessarily com- 
municate inflammation. There are many operations in 
nature in which sulphurized hydrogen gas is produced ; 
but it often forms other combinations, according as it is 
dissolved in water, or is disengaged at a temperature too 
low to be able to inflame. 
When phosphorus is boiled in a solution of potash or 
of lime, there is disengaged phosphorized hydrogen gas, 
which being much more combustible than sulphurized 
hydrogen gas, inflames at a low temperature as soon as it 
comes into contact with atmospheric air. This gas, which 
in chemical experiments exhibits the beautiful spectacle 
of a fountain of fire over water, is produced naturally by 
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