An Interesting Case of Spontaneous Combustion 



BY PAUL C. BOWERS. 



The burning of a large pile of black shale dumped at the edge 

 of the Tennessee River, a little south of Hamburg, has caused 

 considerable excitement and interest in Hardin County because 

 of its spontaneous origin, and long duration. A description 

 and explanation of this rather remarkable incident may be of 

 interest to the readers of this publication. 



The U. S. Government has been dredging the shallow place 

 in the Tennessee River south of Hamburg and a canal, about 

 two miles long, has been excavated out of the rock in the bed of 

 the river. The rock was piled in the water at the edge of the 

 river and consisted mostly of limestone, but for a distance of 

 about a hundred yards the pile was the typical Chattanooga 

 shale. This shale contained a great deal of bituminous matter, 

 even a few pieces of thin lenses of coal, some oil and a consider- 

 able quantity of pyrite and marcasite. 



Pyrite and marcasite are chemical compounds of iron and 

 sulphur. They both have a pale brass-yellow color and resem- 

 ble each other very closely. Marcasite is more easily decom- 

 posed than pyrite and nearly always has a greenish-white, 

 varying to white, powder on its surface. This powder is a 

 mineral, known as melanterite, sometimes called vitriol or 

 copperas. Its chemical name is sulphate of iron. It is soluble 

 in water and tastes like a mixture of iron and alum. This is 

 the first decomposition product of marcasite and pyrite. 



About the 15th of August, 1915, after several days of rain 

 and high water this pile of black shale started burning just 

 above the high water mark. The fire continued over a period 

 of about two months extending along the pile for a distance of 

 seventy-five yards. It was a slow smouldering fire and when 

 fanned by the wind would burst into flames. There was a 

 constant cracking noise which was due to the cracking of the 

 shale by the gas formed on heating the pyrite. Sulphur fumes 

 were very strong, and, as reported by Mr. Bruce Wade, who was 

 doing geological work in this area at the time, the odor was 



