Generally speaking, intrahepatic and postoperative residual gallstones are regarded as not being amenable to surgical therapy. Pribram,1Walters and Wesson,2and Best and co-workers3employed various organic solvents, such as ethyl ether or chloroform, agents which are, however, aimed at dissolution of cholesterol stones. Bilirubin stones, and bilirubin-calcium stones in particular, are scarcely soluble in such organic preparations, and hence arises the question of the toxicity and pharmacologic side-effects of such measures. Although the incidence of cholesterol calculosis is increasing in Japan of late, bilirubin-calcium calculosis is characteristic of this type of involvement in Japan, and its incidence exceeds that of the former4in this locality. Intrahepatic stones, residual gallstones, and most stones of the common bile duct are classified as bilirubin-calcium stones in Japan, and adequate therapy for them is urgently needed.5-7 Chemical Studies One of us (T. H.)8introduced rheologic methods for