Baron A. De Schulten, a political refugee from Finland, worked during the latter part of his life in the chemical laboratories of the Sorbonne in Paris. There he prepared in a crystallized form number of minerals and compounds analogous to them. These were determined crystallographlcally and compared in isonlorphous series. For example, having obtained crystals of artificial monetite, CaHPO4, he then proceeded to prepare the corresponding compounds in which strontium, barimn, or lead take the place of calcium, and arsenic the place of phosphorus. In this series he determined the crystallographic constants and optical data for CaHPO4, SrHPO4, BaHPO4, PbHPO4, SrHAsO4, and PbHAsO4. Crystals of CaHAsO4 were also obtained, but they were too small tbr measurement. Any of these compounds might be expected to occur in nature, but hitherto only monetite has been found as a mineral.

Bolivian minerals have been sent tbr examination and preservation in the British Museum oolleetiml at various times since 1894 by my old school-fellow Mr. Malcolm Robmts, A.R.S.M., now General ganager of the Compagnie Aramayo de Mines en Bolivie. Several of these have been described in the pages of this magazine (see vol. 14, p. 309). Although he has industriously collected Bolivian minerals for over thirty years he is only now rewarded by the discovery of a species new to science. The material which he has been good enough to entrust to me for description was recognized by him as being probably something new, and this was confirmed by a chemical analysis made by Mr. T. Burns MeGhie in the assay office at Quechisla in Bolivia.

An attempt was made to determine the true symmetry of the cleavage flakes of aramayoite by means of the Laue photographic method. Since X-ray diffraction takes place within the crystal, the lack of welldeveloped faces other than main cleavage faces was no disadvantage. One feature, however, which did prove a difficulty, was the pliability of thin clevage flakes referred to by Dr. Spencer. It was essential that the whole of the main cleavage face upon which the X-ray beam was incident should be strictly perpendicular to that beam. In order to ensure this, only those flakes were used which gave a single optical reflection, and two distinct methods of setting were resorted to. In the first case the slit (circular aperture) was used vertically ; the flat end of the slit system was ground truly perpendicular to the slit itself and was thus horizontal.

The crystal used in the first part of this investigation, an untwinned specimen from Ceylon in the British Museum collection, was measured goniometrically and described in detail by Dr. G. F. Herbert Smith, who gave as its crystallographic constants :

Density (p) 5.82 (grs./c.c.). Monoelinic prismatic,

Owing to the comparatively largc size of the crystal and its high absorptive power it was unsuited either to the 'rotating crystal' or Laue photographic methods of X-ray examination, Reflections from the faces were observed on the Bragg ionization spectrometer and spacings measured with an accuracy of about 2 per cent.

In a proper recently published by Prof. Vegard is contained an analysis of the structure of the zircon group of crystals, which belong to the tetragonal holohedral class, the axial ratio being approximately a : c = 1 : 0.656.

As the present work was completed when the above paper appeared, it is interesting to find that the principal deductions concerning the structure of zircon, ZrSiO4, are confirmatory. The parametral values are, however, slightly different. This difference, though small in itself, is found to introduce larger discrepancies between the observed and calculated intensities of reflection.

Small portion (B.M. 1921, 274) of the Vaalbult meteoric iron, weighing about 184 grams, was kindly placed at the disposal of the writer for examination by the late Dr. L. Peringuey, Director of the South African Museum, Cape Town. According to information received from him, this meteorite is known as the 'Vaalbult' siderite, and was presented to the South Afican Museum on April 22, 1918, by Mr. S. Grove, Member of the Provincial Council of the Cape for the Prieska Division, who obtained it from Mr. Japie Greeff, the owner of the farm on which it was found, probably early in the same year. The original mass weighed about 26 lb. and was very deeply and broadly pitted. In external appearance it is somewhat similar to the large (1,210 lb.) Ratteldraai iron from the Kenhardt Division, more than 60 miles distant, found in 1909. A cast of the iron sent by Dr. Peringuey shows that it is of very irregular shape.