150
JOURNAL OF CHEMICAL EDUCATION
JANUARY, 1930
Acknowledgment The writer desires to express gratitude to Dr. Emil Ott of The Johns Hopkins University for reviewing this manuscript and to Miss Marguerite Little of the JOURNAL staff for the drafting of some of the illustrative diagrams employed. He also acknowledges his indebtedness to the following references: W. P. Davey, "Study of Crystal Structure and Its Applications," Gen. Ekc. Rm.,27,742-8, 795-802 (1924); 28, 129-37, 25&65, 342-8, 586-99, 721-30 (1925) ; 29, 118-28, 274-87, 580-9 (1926). Sir William Bragg, "An Introduction to Crystal Analysis," D. Van Nostrand Co., Inc., New York, American edition, 1929. R. W. G. Wyckoff,"The Structure of Crystals," The Chemical Catalog Co., Inc., New York, 1924. George I,. Clark, "Applied X-Rays," McGraw-Hill Book Co., Inc., New York, First edition, 1927. F. K. Richtmyer, "Introduction to Modem Physics," McGraw-Hill Book Co., Inc., New York, First edition, Chapter XII, 1928. Duralumin in Aeronautical Engineering. Duralumin was much in evidence a t Olympia during the International Aeronautical Exhibition and tended somewhat to overshadow the other metals, heavy and light, that enter into the structure of modern airplanes and seaplanes, as well as into that of the engines themselves. Duralnmiu has this in its favor, that with strength it combjnes lightness and a reasanable resistance to corrosion, three essential properties i t is not easy t o attain simultaneously in any other metal. The corrosion resistance is, however, cdgsiderably affected by the nature of the treatment to which the material has been subjected. A valuable article on the subject of duralumin generally has appeared in a recent number of the French journal, Aciers Spkciaux, M6tau.v et Alliages. The author, R. Cazaud, points out that the tensile strength of duralumin is fairly well maintained a t reasonable temperatures, falling 05 by 10 per cent a t 100°C. and by 20 per cent a t 150". At 300DC.,however, the loss of strength is 60 per cent. It corrodes swiftly a t such temperatures. Cazaud repeats the opinion that, from the point of view of corrosion by sea water, duralumin does not behave as well as pure aluminum, but the behavior of varieties containing manganese is superior t o duralumins which do not contain that constituent. Zinc accentuates corrosion, and Cazaud considers that copper has the same effect.-Ch. Age Insulin. Investigations an insulin, carried out by Drs. E. Glaser and G. Haplen in Vienna, have shorn that insulin consists of substances which occur where sugar is degraded-in yeast protein, in the pancreas, in cancerous tissue, etc. They are of the opinion that they have shown that insulin is a compound of guanidine and amino acids. I n various plants, substances were found which behaved like insulin, e. g.. in turnips. Moreover, ferments possessing the ability to lower the sugar content of the blwd were isolated from sheep's liver and horseradish. Of greatest significance is the discovery of the investigators that the action of insulin may be heightened by certain stomach enzymes, by certain substanes obtainable from bone marrow, and-best of all-by expressed yeast juice boiled for eight hours. From the above results it is assumed that insulin, a t first inactive, needs co-ferments t o produce its specific action; that is, i t becomes active only on meeting other substances.-Ckem, Age
