The solubilities of TlCl, TlCNS, and Tl2SO4, were determined in solutions of egg albumin at 25°C. The Tl+ was titrated to Tl+++ with standard KI03 using the ICl endpoint. The albumin concentration was determined by a modified Kjeldahl method. The pH of each solution was obtained with a glass electrode using M/20 potassium acid phthalate as a standard (pH= 3.97). In solutions of egg albumin dialyzed free of chlorides and sulphates and adjusted to a pH of 3.3 it was found that the greater the albumin concentration the greater was the amount of dissolved salt per 1000 g. of water. In albumin solutions at a pH of about 6 and to which no acid had been added a similar phenomenon was observed except that at small albumin concentrations the solubility of Tl2SO4 was less than in pure water. In dilute isoelectric albumin solutions all three salts studied were less soluble per 1000 g. of water than in pure water. These curves passed through a minimum and in some of the more concentrated albumin solutions the solubility became greater than in pure water. The valence and extent of hydration of the albumin cation was estimated from the solubility of TlCl at a pH of 3.3
