摘要：

1. No crystal phase of gallia was found which does not have an exact counterpart in the alumina system. 2. Suitable conditions were found for preparing well-crystallized gallia monohydrate and alpha gallia. 3. The high-temperature form of gallia, which bears the designation beta in the literature, has been shown to be isomorphous with theta alumina. 4. Sodium, potassium, and lithium gallates have been prepared whose structures are completely analogous to the corresponding compounds in the alumina system that bear the names "beta" and "zeta" in the literature. 5. Thermal studies have shown that a considerable evolution of heat accompanies the transition from alpha gallia to the theta-like form, indicating that alpha gallia is metastable in the temperature range considered. A large heat of crystallization was evolved when amorphous alumina crystallized to gamma. A very large exothermal effect was observed when gamma alumina transformed to corundum. The last effect is not readily explained.

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