306 OXIDATION OF METALS. 



combustible body, and oxygen as a supporter of com- 

 bustion. Sucli an arrangement is a most illogical one, 

 since we may burn oxygen in an atmosphere of hy- 

 drogen, in the same manner as we burn hydrogen in 

 one of oxygen ; and so, in all the other cases, the sup- 

 porter of combustion may be burnt in an atmosphere 

 formed of the, so called, combustible. The ordinary 

 phenomena of combustion are, however, due to the 

 combination of oxygen with the body burning therefore 

 every instance of oxidization may be regarded as a con- 

 dition of combustion, the difference being only one of 

 degree. 



Common iron, exposed to air and moisture, rusts ; it 

 combines with oxygen. Pure iron, in a state of fine 

 division, unites with oxygen so eagerly, that it becomes 

 incandescent, and in both cases oxide of iron is formed. 

 This last instance is certainly a case of combustion ; but 

 in what does it differ from the first one, except in the 

 intensity of the action? The cases of spontaneous 

 combustion which are continually occurring are ex- 

 amples of an analogous character to the above. Oxygen 

 is absorbed, it enters more or less quickly, according to 

 atmospheric conditions, into chemical combination ; heat 

 is evolved, and eventually, the action continually 

 increasing, true combustion takes plaee. In this way 

 our cotton-ships, storehouses of flax, piles of oiled-cloth, 

 saw-dust, &c., frequently ignite; and to such an 

 influence is to be attributed the destruction of two of 

 our ships of war, a few years since, in Devonport naval 

 arsenal.* 



* Being called upon by the Solicitor for the Admiralty to ex- 

 amine into the causes of the fire which destroyed the Imogene 

 and Talavera, in Devonport Arsenal, I discovered a bin under the 

 roofing which covered these ships, in which there had been accu- 

 mulating for a long period all the refuse of the wheelwrights' and 

 painters' shop ; and it was quite evident that spontaneous com- 

 bustion had taken place in the mass of oiled oakum, sawdust, anti- 

 attrition, and old sail-cloth, there allowed to accumulate. 



