1. Field of the Invention
This invention relates to crucibles and particularly to crucibles for use in chemical analysis, such as coal and coke analysis.
2. Description of the Prior Art
To predict the behavior of coal in a furnace, certain tests have been developed and procedures called proximate analysis have been established by ASTM for quantitatively determining the percentage of moisture, ash and volatile matter in a coal sample. The percentage of fixed carbon in the sample can then be calculated as the difference. The ASTM testing procedures are prescribed in ASTM D3173-73 (Reapproved 1979), D3174-73 (Reapproved 1979), D3175-77 and D3172-73 (Reapproved 1979).
These tests require that the samples be loaded in crucibles for weighing and for heating in a laboratory furnace. Various types of crucibles have been proposed for use in coal and coke analysis such as those disclosed, for example, in U.S. Pat Nos. 1,609,096 and 1,720,327. Prior crucibles have not been entirely satisfactory, however, since they did not have a cooperating lid which would properly seal to exclude air and release volatiles from the crucible as required during testing.