The invention is an apparatus for determining a temperature at which a
phase change occurs in a fluid sample, a method for measuring a
temperature at which a phase change occurs in a sample and a sample cell.
An apparatus for determining a temperature at which a phase change occurs
in a fluid sample 60' in accordance with the invention includes a sample
cell (12')for providing direct collection of the sample from a sample
source (74) which is collected and retained at a collecting end thereof
by capillary attraction between the collecting end and the sample, the
sample cell including a longitudinal passage (78) extending from the
collecting end to a far end through which light is transmitted to provide
an image of the sample as retained at the collecting end of the passage
and with a cross sectional area of the passage being greater at the far
end than at the collecting end; a heating and cooling assembly (14),
including a temperature sensing device (44), the heating and cooling
assembly holding and thermally contacting the sample cell during the
determining of the temperature by the temperature measuring device at
which the phase change occurs while the sample is positioned in the
collecting end; and an illumination system (16) for directing a light
beam to the collecting end, through the sample, through the longitudinal
passage and out of the far end to permit viewing of the sample from the
far end to determine the temperature at which the phase change occurs.