That the presence of an hydroxyl group is the determining influence in causing polymerization of the nickel and cobalt salts receives, however, no support from the results obtained by applying methods similar to the above to the malonates and tartronates of nickel and cobalt. Conductivity and freezing-point determinations were carried out with these salts and also with the magnesium salts of the same acids. The malonic acid was a preparation of Merck. The tartronic acid was made from dinitrotartaric acid according to Demole.1 The yield was small, which accounts for only one set of determinations having been made. Molecular conductivities are given in Table V, and depressions of the freezingpoint in Table VI. To bring the results of these two tables to a uniform basis, interpolations have been made graphically, exactly as in the preceding cases. These interpolated values will be found in Tables VII and VIII. Magne v. 16.. Nickel. Cobalt. .... .... 32. .... sium. (Walden.) Nickel. Cobalt. sium. 23.0 30.0 43.0 32.0 26.5 34.7 52.6 25.5 42.3 29.9 37.8 51.5 It is seen in these cases as heretofore, that the nickel and cobalt salts possess lower molecular conductivities and higher apparent molecular weights than the corresponding magnesium salts. Al Malonates. Magne- ... ... though the conductivities of all these salts are less than for the corresponding succinates, still the relative differences between the conductivities of the nickel, cobalt, and magnesium salts are about the same as in the case of the succinates. No such differences exist, as were found between the conductivities of the tartrates and malates of magnesium and those of the corresponding nickel and cobalt salts. The conductivities of the magnesium salts of malonic and tartronic acids are considerably less than the conductivities of any of the other magnesium salts investigated. This was noticed by Walden in the case of the malonate. Bredig's explanation of such behavior has already been referred to. The important point to notice in connection with these last results is, however, that the conductivities of the nickel and cobalt tartronates are not appreciably less than the conductivities of the same malonates, although tartronic acid possesses an hydroxyl group. Any explanation of the conduct of these salts based on the presence of an hydroxyl group in the molecule, therefore, appears to be untenable. Before letting the question rest here, however, a few considerations bearing upon the point under discussion will be mentioned. The strength of the acids of the succinic acid series (i. e., succinic, malic, and tartaric acids), as is well known, increases with the number of hydroxyl groups present, Ostwald's affinity constants being for succinic acid 0.0066, for malic acid 0.0395, for tartaric acid 0.097. The hydroxyl groups have therefore a distinct effect on the strength of the acids. In the case of malonic and tartronic acids a very different effect is observed. The Ostwald constant for malonic acid is 0.158 and for tartronic acid 0.107; that is, the introduction of an hydroxyl group has here decreased the strength of the acid. Such being the facts with regard to the acids, it seems probable that salts of the succinic acid series might show very different gradations in properties from the same salts of the malonic acid series. Then before asserting that the presence of the hydroxyl groups in malic and tartaric acids has no effect on the behavior of their nickel and cobalt salts, it is necessary to extend investigations similar to these to the salts of the glutaric acid series or some higher one. Such work is contemplated in the future. 1 The values given are for K = 100k. See Ztschr. phys. Chem., 3, 418 (1889). In conclusion, however, it may be stated that aqueous solutions of nickel and cobalt salts of dibasic organic acids offer greater resistance to the passage of the electric current than solutions of similar salts of the other metals investigated, notably magnesium, and that this resistance is exceptionally great in the case of the tartrates and malates of nickel and cobalt. This abnormal behavior of the last-named salts is also confirmed by the results obtained with the freezing-point method for determining molecular weights. WESTERN RESERVE UNIVERSITY, [CONTRIBUTION FROM THE HAVEMEYER LABORATORIES, COLUMBIA UNIVERSITY, NO. 69.] ON THE MANGANESE FERROCYANIDES. BY ALBERT ERNEST DICKIE. Received August 2, 1902. THIS work was undertaken to throw further light on the composition of the manganese ferrocyanides as seemed warranted by the discrepancies in the results obtained previously by Wyrouboff‚1 Stone and Van Ingen, and Miller and Mathews.3 2 Wyrouboff, by precipitating a manganous salt with potassium ferrocyanide, obtained a compound to which he ascribes the formula 5Mn, Fe(CN),.4K4Fe(CN)6.4H,O, and by using hydroferrocyanic acid he obtained the normal manganese ferrocyanide Mn,Fe(CN),.7H2O. In either case he found it to be immaterial which reagent was used in excess. Stone and Van Ingen obtained results expressed in atomic ratios. as follows: Miller and Mathews obtained in slightly acid solution: With excess of ferrocyanide ..... 100 105 to 108: In the new series of experiments we have obtained: From the above comparative statements of results the reader is left to draw his own conclusions. NOTES. Note on the Preparation of Metallic Lithium.-The following method is a modification of that of Bunsen and Matthiessen for + the electrolysis of fused lithium chloride, and will be found to give good results. |