In the course of a study of the crystal structure of β-glycine a Geiger counter diffractometer was successfully utilized for the measurement of the integrated intensities from a single crystal. This paper describes the apparatus used and the method for measuring them. A proportional and a scintillation counter were tested for the measurement. A comparison has been made between these counters and their relative merits are discussed.

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Serpentine-like materials associated with clinozoisite rock in serpentinite were investigated with chemical, X-ray and thermal methods, and it was revealed that the materials are mechanical mixtures of two polymorphic minerals, namely, aluminian serpentine and chlorite which are chemically similar (intermediate between serpentine and clinochlore) and of low crystallinity. The aluminian serpentine has an ortho-hexagonal cell and belongs to the aluminian serpentine series recently synthesized. The closely associated chlorite may have also an ortho-cell.

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The re-examination of the crystal structure of α-hexagonal BaAl₂Si₂O₈ has revealed that the true symmetry of the crystal is lower than hexagonal-possibly, orthorhombic with a body centered lattice of dimensions: a=5.293, b=9.168 and c=7.79×2Å, and the crystals invariably occur in a trilling form made up by three orthorhombic individuals, simulating a hexagonal symmetry. Since it was not possible to distinguish the reflexions of each individual crystal from those of the others, the avarage structure with the hexagonal lattice, a=5.293, c=7.790Å, was investigated by the use of three-dimensional Fourier methods. The structure thus determined shows that the hexagonal (Al₂Si₂)O₈ sheets, which were reported in the previous work, are not exactly as such but trigonal owing to a slight deformation. In the structure, the barium atoms are coordinated by six oxygen atoms with the distance of 2.89Å, and the Si1/2Al1/2-O distances vary from 1.65 Å to 1.67 Å, giving the mean value of 1.66₅ Å.
A closer examination of the structure of the β-form on the basis of X-ray powder diffraction patterns and oscillation photographs taken at temperatures above 300°C. appears to disclose that the structure of the form is exactly hexagonal with a=5.313Å, c=7.805 Å (at about 450°C.). The space group is D¹_6h and there is one formula unit per cell. Thus the (Al₂Si₂)O₈ sheets in this form display a regular hexagonal symmetry, and the α-β inversion would be adequately explained as due to the change in configurations of the (Al₂Si₂)O₈ sheets from hexagonal to trigonal and vice versa.

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