PROBLEM TO BE SOLVED: To provide a rapid and accurate measuring apparatus for surfactant characteristics that uses the same strain gauge for measuring surface tension for measuring both surface suction and surface diffusion, and surface tension - area curve, and contrives to retain consistency in data and to control the measuring apparatus by a computer.
SOLUTION: The inside of a container body 7 in a measuring apparatus A is divided into upper and lower portions by a support member 8. Then, a circular tank 10 that is placed in a heater section 9 for the circular tank and a rectangular tank 12 that is placed in a heater section 11 for the rectangular tank are provided at one side or the other of the support members 8, respectively. A strain gauge 13 is provided between the circular tank 10 and the rectangular tank 12. By rotating a knob 15 for rotating left and right in a strain sensor section 14 of the strain gauge 13 by 180°, both measurements can be made in the circular tank 10 and the rectangular tank 12. The measuring apparatus A is connected to a personal computer and a printer 2, and various measurements can be made by varying measurement conditions.