CURRENT TOPICS. 77I
mist of sulphuric acid and prevents its escape. After digestion has been completed, the tube may be washed with water to recover any traces of ammonium salts which have been carried into it with the spray. The inventors describe the device as simple, cleanly, convenient, inexpensive, and efficient. J. S. H. Electrometfic Method for the Detection of the Relative Freshness of Fish.--MAuRICE E. STANSBY AND JAMES M. LEMON (Ind. and Eng. Chem., Analytical Ed. I933, V, 2o8-2II) have devised an electrornetric test to determine the relative freshness of haddock. The method is based on the measurement of buffer capacity. The finely ground meat is well mixed with water, quinhydrone is added, and the mixture is titrated, first to a pH of approximately 6.o to measure the amount of end products of bacterial decomposition (secondary decomposition), then to a pH of approximately 4.3 to obtain an inverse measurement of the primary changes or protein hydrolysis. J. S, H. A Thirteenth Century Book on Stones.--Under this title, MARY LOUISE FOSTER (Jour. Chem. Ed., i933, X, 369-372) describes
the manuscript known as "E1 Lapidaris de Alfonso el Sabio" which was prepared in I278 by direction of Alfonso X of Aragon, and is based on both Arabic and Chaldean sources. Among the minerals and rocks described are magnetite, gold, silver, lead, mercury, pearls, limestone, asbestos, and bezoar. The four folios describe 492 stones. The bezoar was regarded as a panacea in the Middle Ages; today it is classified as a gastrolith or gastric calculus, a mineral mass deposited in the stomach of an animal. Similar intestinal calculi are also known. J. s. H.
Substitute for Equivalent Weight.--The equivalent weight of an element (or compound) is obtained by dividing its atomic (or molecular) weight by its active valence. CHARLES N. OTT (.Tour. Chem. Ed., 1933, X, 312) suggests that the term "equivalent weight" be replaced by "univalent weight" since it actually represents that weight of an element or compound which might be considered to have a valence of I.
J. s. H.