No abstract

Glycerol and sucrose or dextrose are often used together in cake icings, candies, sirups, and pharmaceutical elixirs. In planning a recipe or formula that will prevent or promote crystallization of the sugar, as the need may be, it is important to know the solubility of the sugar. Solubilities of sucrose in several concentrations of aqueous glycerol were determined at 15°and 35°C. Solubilities of dextrose were determined at 15°, 25°, and 35°C. Sucrose is more soluble than dextrose at lower glycerol concentrations but dextrose is the more soluble at higher glycerol concentrations. The solubility of both sugars is decreased by increased glycerol concentration and by lowered temperature.Glycerol is used as a humectant, to improve the texture and consistency of candies, icings, and sirups, and in pharmaceutical elixirs and cough sirups. It is desirable to know the solubilities of the common sugars, sucrose and dextrose, in aqueous glycerol at ordinary temperatures in order that crystallization may be prevented or promoted, as the need may be. Sucrose solubilities at 15°and 35°C. and dextrose solubilities at 15°, 25°, and 35°C. are reported. Sucrose solubility at 25°C. has been previously reported (3). Glycerol concentrations of from 25 to 95% by weight were used.

This newcomer to the textbooks on colloid chemistry is one of the best reviews of the subject. It is addressed to graduate students or to advanced undergraduates in chemistry, as well as to students in allied sciences.The author rightfully states that, "The science of colloid chemistry bridges the gaps between the various physical and biological sciences. It has become an indispensable tool without which it is impossible to explain many scientific phenomena. It is the one field of chemistry which can claim to be the chemistry of everyday life."The book is refreshing in that it is not simply a rehash of some of the material in a few leading texts filled out by references to papers which happened to have been published in the last year or two.On the contrary, it is a fair cross-section through the material in this field, and the references are distributed over the most important papers throughout the whole development of the subject. The theoretical side is somewhat weak, but this in part reflects confusion among various schools, and it is fully compensated for by the wealth of interesting factual matter. Several chapters might be modernized. For example, the discussion of sedimentation hardly does justice to Svedberg's oil turbine ultracentrifuge or to the established theoretical treatment of Mason and Weaver, Lamm, Faxen, and Archibald.The book consists of four parts. The first comprises surface chemistry, including adsorption and catalysis. The second is devoted to the preparation and properties of lyophobic systems with separate chapters on aerosols, emulsions, and foams, dialysis and ultrafiltration. The third part deals with lyophilic systems, sols, gels, and jellies. Part IV gives much interesting information with regard to the biocolloids, with further chapters on foods, biocatalysts, colloid factors in growth and movement, and colloids in the blood and nervous system, concluding with one on colloidal medicines. At the end there is a five-page list of reference books.The book is beautifully illustrated, and the text is particularly clear. It should be widely read. The factual information will appeal to the imagination of many students and lead to their giving the subject much closer attention.

Chemists' Soc., 30, 420 (1953).(66) Ibid., in press.

SummaryA new method of analyzing mixtures containing monoglyceride and glycerin is presented. It is based upon oxidation of the sample with periodic acid. The new method is more rapid than the older methods because it is not necessary to separate the two layers when the glycerin is extracted from the solution of the sample. Precision of the titrations is improved because in the older methods the sample titration must equal at least 80% of the blank titration, but in the new method the sample titration can be very small and a correspondingly greater difference represents the monoglyceride or glycerin in the sample.