Liquid quality-evaluating apparatus

A liquid quality-evaluating apparatus for determining the boiling point or vapor lock point of a liquid, comprising:

• a vessel made of heat-conductive and electrically conductive material and having an opening to receive a prescribed amount of a sample liquid whose boiling point or vapor lock point is to be determined;
• a discharge siphon, one end of which is disposed at the bottom of the vessel for communication with the liquid in the vessel and the other end of which extends outside of the vessel, for removing the liquid from the vessel after its quality has been evaluated;
• a removable cover made of heat-insulating material to substantially airtightly close the opening of the vessel;
• heating means for heating the vessel and the liquid in the vessel;
• an electrode, one end of which is removably received in the vessel for contact with the sample liquid whose boiling point is to be determined and the other end of which is fixed to the removable cover;
• a current cutoff-detecting circuit including at least the electrode, the vessel and the sample liquid received in the vessel to form a closed electrical circuit and adapted to issue an output signal when the sample liquid ceases to contact the electrode, thereby detecting a predetermined level of the liquid in the vessel;
• means for detecting the temperature of the sample liquid in the vessel and for generating electrical signals corresponding to the detected temperature;
• and
• display means coupled to the temperature detecting means for indicating in response to said electrical signals whether the sample liquid in the vessel has a higher or lower boiling point than a reference temperature.