OXIDATION AND DETERIORATION OF COAL. 299 
corrections are comparable, and I believe that irregularities in 
the samples and manipulation could not have produced errors of 
any consequence. 
Two 250-gram samples of each coal, one in air and the other 
in oxygen,? were stored for about nine months in 7-liter bottles 
at about 30° C. in an ordinary room lighted by diffused sunlight. 
The bottles were stoppered with rubber stoppers through each 
of which passed two glass tubes by means of which the gas 
samples were taken. Fresh air was frequently supplied with a 
bulb to those bottles containing air. The small size of the coal 
particles offers a greater surface in proportion to the mass and 
thus facilitates the absorption of oxygen. Analyses of the 
samples before and after storage are as follows: 
TABLE I— Analyses and calorific values of Philippine coals stored in air 
and oxygen respectively. 
Original sample. After storage in air. |After storage in oxygen. 
Coal | 
SO arora |lcombus:|- Fixed Cal- | Moi Cal- | Moi 
ois- |combus-| Fixer al- ois- al- ois- | ° 
ture. tible | carbon. Ash.b ories.c| ture. Ash: ories. | ture. Ash. |Calories. 
matter.3| 
Per ct. | Per ct. | Per ct. | Per ct. Per ct. |Per ct. Per ct. |Per ct. 
1 5. 90 46.30 40. 08 7.72 | 6,159 BG) |) TERRA |] (sath) 5.75 | 8.11) 6,059 
| 2 8.61 40.67 46. 55 4.17 | 6,012 8.75; 4.50} 5,931 8.03 | 4.25 | 6,022 
3 11.55 87. 43 46.95 4.07 | 6,066 11.11} 4.47) 5,985 11.18} 4.20) 5,982 
a After the method of Cox, This Journal, Sec. A (1907), 2, 41. 
b Each analysis shows somewhat less ash than the ordinary coal from the same source 
because of the way in which the samples were prepared. 
© Average of three closely agreeing, independent determinations. 
The above calorific values are not comparable as they stand, 
since the samples contain different quantities of diluents (water-- 
ash).? When they are caleulated to an ash- and moisture-free 
basis, coal— (water--_ash), we then deal with alterations in the 
pure coal substance, and the results show that in each case the 
calorific value is lowered by storage as given in the following 
table: 
* Ordinary commercial oxygen, free from carbon dioxide, 91.5 per cent 
of which was absorbed in alkaline pyrogallol, was used. The bottles were 
alternately partially evacuated and filled with oxygen from the bomb, 
until the gas left in the bottles was practically commercial oxygen. 
*This does not represent the original amount of ash with its hydrated 
silicates and with its iron pyrites instead of ferric oxide formed by burning 
[Parr and Wheeler, Journ. Ind. & Eng. Chem. (1909), 1, 636], but the 
same coal burned to ash in the same way unquestionably gives concordant 
results. 
