Water surface profiles were observed in nitrogen and oxygen atmosphere
s in gradient magnetic fields, ranging from 0.6 T to 8 T. In the case
of a nitrogen atmosphere, the water surface was suppressed in the regi
on exposed to high fields only by the diamagnetism of water (''Moses e
ffect''). In the case of oxygen, however the water surface was further
suppressed because of the increased oxygen pressure in the field. The
change in oxygen pressure, estimated experimentally from the differen
ce in the water level, agreed quite well with the theoretical value, h
ence suggesting that the observation of the surface profile of a liqui
d can provide a potential method for obtaining the change in the gas p
ressure in a strong magnetic field.