The effects of additional elements on the allotropic transformation point of cobalt can not be expected, as they are not attributed to a single factor. Although the simple conclusion from the results of this work can not be given, the following matters may be said to be cleared out.
1. Elements with body-centered cubic lattice, for example, Li, Ta, Cr, Mo, W, Na, K and V, raise the allotropic point.
2. Elements with the crystal form of antimony type, for example, As, Sb and Bi, raise the allotropic point.
3, Elements with face-centered cubic lattice, for example, Cu, Ag, Au, Fe, Ni and Al, lower the allotropic point.
4. Among Elements with close-packed hexagonal lattice, Mg and Zn lower the allotropic point, but Ca (over 450°), Be, Ti and Zr raise it. Therefore their effect can not be judged in a simple manner.
5. While Mn lowers the allotropic point, Si raises it.

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The effect of annealing at 120°, 200°, 290°, 380° and 470° on the corrosion of pure magnesium and its alloys, Mg-Al (1, 3, 7, 11%), Mg-Zn (2, 4, 7%), Mg-Sn (2, 4, 6%), Mg-Cd (2, 4, 6%), Mg-Si (0.62, 0.52%), Mg-Mn (0.90, 2.28%), Mg-Zn (4%)-Al (1, 3, 6%) and Mg-Zn (4%)-Al (1, 3, 6%)-Mn (0.3%) which cast in dry-sand-moulds, was studied. The change of micro-structure of those alloys by annealing was also observed. The following results were obtained. The rate of corrosion for pure magnesium, Mg-Zn (less than 2%), Mg-Cd, and Mg-Mn (less than 2%) alloys decreases with the rise of annealing temperature; for Mg-Si alloys it increases first by annealing and then decreases as temperature rises; for alloys containing aluminium the annealing at a temperature up to 290° has no effect, and above this temperature it is markedly harmful which is noticeable to an appreciable extent when aluminium content is low and this point appears at higher temperature as manganese content increases. The effect of annealing temperature on the corrosion of Mg-Zn, Mg-Sn, Mg-Cd and Mg-Mn alloys has a relation to its change in structure, but for pure magnesium, Mg-Si and alloys containing aluminium the effect is impossible to explain by change in structure.

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In succession with the former determination of the solubilities of H₂ and N₂ in pure iron, the absorption of H₂ with 10 kinds of elements and with 8 kinds of binary ferreous alloys has been determined in the present investigation by means of the same apparatus and procedure as described in the previous paper, and the results have been compared with their equilibrium diagrams. The results of the investigation are as follows. Mn, Ni, Cr, Si and Cu absorb H₂ at high temperatures, the quantity increasing with rise of temperature; the solubility of H₂ in Mn changes abruptly at the transformation point α Mn _??_ βMn, Ti and V absorb a large quantity of H₂ at lower temperatures forming their hydrides, but the absorption of H₂ by W and Mo has been undetectable by the present experimental conditions. The solubilities of H₂ in the range of solid solution of alloys, Fe-Ni, Fe-Cr, Fe-Mn and Fe-Al determined with the continuous change of composition indicate neither an abrupt change nor a straight line but continuous curves with a maximum or a minimum. In the range of composition of a mixture of two phases the solubilities, determined with alloys of Fe-Cu system, change from one side to the other indicating a linear relation with the composition. The solubility of H₂ in alloys of Fe-Si system is large at lower temperatures, especially in the case of cooling procedure, and the tendency of their temperature-solubility curves is similar to those of the hydride forming elements such as Ti and V.

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The change of lattice-orientation due to the allotropic transformation in boracite, leucite and anhydrous sodium sulphate crystals Was investigated. The general relation that when a modification transforms into another, a particular direction in the first crystal becomes also a particular direction (in the same meaning) in the new crystal-lattice, is found to hold for the above crystals.

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