By burning a 0.2-g sample in a strongly oxidizing atmosphere and weighing the quantities of carbon dioxide and water vapor emitted as the products of combustion of the sample. The carbon dioxide is absorbed in a solution of potassium hydroxide for weighing, while the water vapor is collected in a calcium chloride tube.

The percentage of ash in the coal is found by heating a 1-g sample to approximately 1340 F. In the presence of oxygen, this high temperature assures the complete burning of all complete burning of all combustible in the fuel, and the residue is ash

% of Nitrogen andsulfur are found by complex chemical analysis on different small samples of the fuel. The percentage of oxygen is computed as the difference between the sum of the percentages of the other five items and 100.