  We present 1.4-mm BIMA observations with subarcsecond resolution of the
bright dust and molecular line emission from hot cores associated with a sample
of four ultracompact HII regions: G9.62+0.19, G10.47-0.03, G29.96-0.02,
G31.41+0.31. Density power laws can reproduce the observed continuum emission
but break down on scales smaller than 2000 AU. A total of 38 transitions from
18 species are detected, with G10.47 and G31.41 showing the greatest number of
lines. In particular, these sources display emission from two
collisionally-excited transitions of methanol lying more than 950 K above the
ground state. Outflows traced by H2S emission provide evidence for embedded
exciting sources and the observed morphology of molecular lines is consistent
with internal heating of the cores.
