We present measurements of Zeeman splitting in SO J(N) = 1(2)-1(1) line emi
ssion/absorption arising from dense thermal gas (>10(6) cm(-3)) associated
with ten compact H II and star-forming regions. No line-of-sight magnetic f
ield, above an average 1 sigma limit of 0.57 mG, is detected toward any of
these sources. The W3(OH) region, found in a previous study to have a line-
of-sight field of 3 mG in its dense gas, is thus unique in this respect. Th
e implication of this study is that the magnetic fields in dense clouds are
supercritical in the sense that they are not capable of supporting their h
ost clouds against gravitational collapse. The relatively low average field
limit is consistent with those theories predicting the quick onset of and
short timescales for ambipolar diffusion. Also presented are (1) Zeeman spl
itting measurements of the CCS J(N) = 1(0)-0(1) line probing the 10(4-5) cm
(-3) gas towards three positions in the Taurus star forming region, giving
a 1 sigma average upper limit of 66 muG, and (2) measurements of Zeeman spl
itting in the OH (2)Pi (3/2) J = 7=2 F = 3(+)-3(-) hyperfine line toward th
e compact H II regions DR-21 and G10.62.