In regard to a clinical study of unipolar limb lead, the methods, such as Wilson's, Shimizu-Fujito's, Goldberger's etc. are widely adapted. However, each of these methods can not always be said to be perfect in itself in the sence that the human body is a limited conductor of electricity. Through the immersion experiment at a hot spring bath of Yamanaka National Hospital, I have come to the following conclusion. (1) The electric strom potential of the body laid on its back in water is constant having no relation with its depth of water. It is also constant at any position of the body on its left side in the water deeper than 10 cm and on its right side deeper than 18cm. (2) The electric conductivity of the water in the spring in Yamanaka is 10×10^-4ohm^-1cm^-1 (18°C) and it increases 2×10^-4ohm^-1cm^-1 for every rising of 10°C. This indicates that it corresponds to the salt-solution of 0.071∼0.072% and is 100 times as better as city-water in its conductivity. (3) As for the influence of bathing upon the electrocardiogram, little change is recognized before and after bathing. (4) When in water the different electrode is placed at a neighbouring corner of the left shoulder and the different one to the corner of the tub, or to the opposite corner, the same curved-line is obtained in either cases, that is, the unipolar limb lead is brought about in the immersion experiment. (5) In order to take my unipolar limb lead, it is necessary to lay the body parallel, with water level, although the potential of the upper limb is unchanged with its position and its motion in water. (6) If much attention is paid to keep well the conditions above mentioned, the absolute unipolar lead may be possible.

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