At the Washington office, microscopic investigations into the life
history of coal, lignite, and peat are being conducted. These
investigations have already progressed far enough to admit of the
identification of some of the botanical constituents of the older peats
and the younger lignites, and it is believed that the origin of the
older lignites, and even of some of the more recent bituminous coals,
may be developed through this examination.
In the chemical laboratories, in Building No. 21, the hoods (Figs. 11
and 12) are of iron, with a brick pan underneath. They are supported on
iron pipes, as are most of the other fixtures in the laboratories in
this building. The hood proper is of japanned, pressed-iron plate, No.
22 gauge, the same material being used for the boxes, slides, and bottom
surrounding the hood. The sash is hung on red copper pulleys, and the
corners of the hood are reinforced with pressed, japanned, riveted plate
to which the ventilating pipe is riveted.
[Illustration: Fig. 12.