OXIDATION AND DETERIORATION OF COAL. 301 
The glass tubes carried by the rubber stoppers of the storage 
bottles were closed with rubber tips which, as well as the stop- 
pers themselves, deteriorate so rapidly in a tropical climate that 
it was impossible to keep the bottles tight. The analyses indicate 
that as fast as oxygen was absorbed by the coal it was replaced 
by air. The bottles which contained the coal stored in oxygen 
were refilled with oxygen after they had been sampled for the 
analyses of Table I, and after fifteen months the composition of 
the gases above the coal samples was as follows: 
TABLE V.—Composition of gases above coal in second stage of storage 
m oxygen. 
Volume percentages. 
Geet 
0. ei 
Carbon Remain - 
dioxide. Oxygen. der. 
1 14.6 42.9 42.5 
2 10.3 39.8 49.9 
3 25.7 29.1 45.2 
4 14.4 30.7 54.9 
5 63.0 7.2 29.8 
These results show further deterioration of the coal samples, 
and, taken with those of the next preceding table, indicate that 
the evolution of carbon dioxide is not simultaneous with the 
absorption of oxygen, but is subsequent to it. It is possible that 
a number of oxidation processes varying in character and speed 
of reaction are involved, depending on the kind of coal, the stage 
of the process, etc., but the facts are satisfactorily explained 
by the assumption that oxygen is absorbed by the unsaturated 
chemical compounds of the coal to form organic peroxides, and 
carbon dioxide is evolved when the peroxides break down.® In 
cases of autoxidation, hydrogen peroxide has been frequently 
met with, and it is probable that in the autoxidation of coal the 
organic peroxides may be hydrolyzed slowly by water to form 
* Porter and Ovitz, Journ. Am. Chem. Soc. (1908), 30, pt. 2, 1489, note 
that some coals rapidly absorb oxygen from the air surrounding the coal 
during storage without forming carbon dioxide; however, the maximum 
duration of their tests was one hundred four days and from their own 
numbers the content of carbon dioxide began slightly to increase after 
thirty-four days. Also idem, Journ. Ind. & Hng. Chem. (1910), 2, 80, 
“Coal absorbs oxygen from the air during storage without forming carbon 
dioxide and the amount of oxygen absorbed accords approximately with 
the deterioration in heat value.” 
“Brooks, This Journal, Sec. A (1910), 5, 219, offered this hypothesis to 
explain the oxidation of Manila copal by the air. 
