THE publicatíon of Prof. Arrhenius's Silliman lectures on “Theories of Solutions,” delivered at Yale in the spring of 1911, will be welcomed by all who are interested in the present position of physical chemistry. The book is of special value because the author has dealt very lightly with those aspects of his theory of “electrolytic dissociation” which have been discussed over and over again during the last twenty-five years and have occupied so large a space in nearly all recent text-books of physical chemistry. Thus, although many of his illustrations are drawn from electrolytic solutions, only three of the eleven lectures deal specifically with such solutions, namely, those on “The Theory of Electrolytic Dissociation” “Conductivity of Strong Electrolytes,” and “Abnormality of Strong Electrolytes.” Theories of Solutions. Svante Arrhenius. Pp. xx + 247. (New Haven: Yale University Press; London: Oxford University Press, 1912.) Price 12s. 6d. net.