206 Transactions of the American Institute. 



cotton, and rags saturated with oil, absorb air, which raises their tem- 

 perature until they take fire. Some of the greatest fires have origin- 

 ated from the spontaneous combustion of finely divided substances. 

 Drying oils used by painters are specially liable to oxydation ; and 

 where tow or rags are moistened with these oils oxydation takes place, 

 and the temperature rises until they suddenly burst into flame. Olive 

 oil, falling into saw-dust, will take fire. And even tape measures 

 have been known to take fire. The fine oil-silk covers for umbrellas, 

 when several have been placed together, have been known to take 

 fire. Hay often absorbs oxygen so rapidly as to burn with flame. 



Some years since, before this fact of spontaneous combustion was 

 so well established, Professor Graham, investigating the cause of the 

 burning of her majesty's ship Imogene, traced it to a bin containing 

 a mass of oakum, which had burst into spontaneous combustion. 



Coal often takes fire spontaneously. Where heaps of coal are 

 kept, they have been found, at a temperature of not over 150° 

 Fahrenheit, to take fire spontaneously. In one case, the coal was 

 sulphureous, and the combustion was referred to the sulphur ; but 

 this accident frequently takes place where the amount of sulphur is 

 very small ; and it is due, not to the oxydation of the sulphur, but 

 of the substance of the coal itself. 



Even the rusting of metals may raise their temperature considerably. 

 In the manufacture of one of the early telegraph cables, about 163 

 miles were made and placed in a tank of water. This cable was 

 composed of copper wires, wound with tow, and protected by a coat- 

 ing of iron wires. It was found that the tank leaked, and it became 

 necessary to draw off the water to repair it. This left the iron wire 

 moist, and in contact with the moist tow, and although the tempera- 

 ture of the atmosphere fell several degrees, the temperature of the 

 cable rose 10°, and there was danger of the temperature rising, from 

 the oxydation of the iron, to such an extent as to destroy the cable. 



The use of sheet-iron, as a covering for wood, introduces a new 

 danger. Iron is such a good conductor that the heat passes through 

 it and chars the wood beneath. Steam-pipes often contain steam at a 

 high temperature, and the heat may change the character of wood 

 exposed to it to such a degree as to cause it to take fire from very slight 

 causes. Such has been the case with Perkins' hot-water apparatus ; 

 and several cases of fire have occurred from wood actually set on fire 

 by pipes containing water at a high temperature. 



Some years since there was a very general belief in the spontaneous 

 combustion of the human body. In 1825, a woman burned to death 



