Examination of a series of examples of vein-breccias demonstrates that while many have readily explicable characters in common, others differ from ordinary types, and exhibit peculiarities calling for special investigation.

In the south-west coal-field of east Glamorganshire—especially in the Lower Coal Measures–Mr. A. Tait, of Caerphilly, observed last year a white, soft, and pulverulent substance, saponaceous to the touch. A specimen sent to me, examined first and identified by Mr. T. Crook, was found to consist of a congeries of well-defined crystals of kaolinite. The crystals are chiefly basal flakes, hexagonal in outline, and 0.02 to 0.037 mm. in length. Most of them show elongation in one direction, and unequal extension of the thin lamellae composing them.

In a recent number of the Mineralogical Magazine an analysis of strüverite found in perak was published. This mineral was submitted to me by Mr. R. L. Corbett for examination in August, 1909, and as I failed to detect its relation to the Piedmont strüverite described shortly before, the material was forwarded to the Imperial Institute in accordance with an arrangement between the Institute and the Federated Malay States Government. While waiting for the results of the analysis, the locality from which the mineral came was traced and some prospecting work carried out to ascertain the amount of material available. This work afforded information that is of interest concerning the origin of the mineral.

The accompanying diagram (Plate VIII) has been prepared in order to facilitate the determination of indices of refraction with the Kohlrausch total-reflectometer, by affording a means of rapidly werking out the results by a graphical method.

The Kohlrausch instrument enables measurements to be made of the critical angle θ, at which total reflection begins, when monochromatic light is reflected at the plane surface of a solid of refractive index μ immersed in a liquid of higher refractive index μ′.

Professor H. Louis, of Armstrong College, handed over to me for examination some crystals of gypsum which had been sent to him by Mr. Frank E. Lott, A.R.S.M., F.I.C., of Burton-on-Trent. Mr. Lott has kindly furnished me with the following particulars.

The crystals were deposited in an apparatus employed for raising steam in the production of distilled water. This apparatus consists of a copper vessel enclosing steel steam pipes for heating the water. The crystals were deposited on the walls of the copper vessel and on the steel pipes, and had been formed within a period of twelve months.

The beautiful crystals of colemanite from the Death Valley, Inyo County, and from the Calico district, San Bernardino County, California, were described almost simulfmneously in the autumn of 1884 by several different observers, The most complete examination we owe to Jackson, who identified forty-forms and determined the axial ratios which are usually accepted for the mineral, namely, a : b : c = 0.774843 : 1 : 0.540998 : β = 110° 9′ 15′′. Very similar values for these constants were adopted by Hiortdahl and by vom Rath.

The inquiry that I have recently made into the weight of the ‘Cullinau’ diamond has led me to clear up, as far as possible, various discrepancies in the published statements respecting the other large diamonds of South Africa. Although a knowledge of the exact weights of these stones is a matter of only trivial scientific importance, yet it is desirable to place on record any definite facts that may still be gathered respecting them. Much valuable information in this direction has been freely given to me by Messrs. Wernher, Beit & Co., through whose hands several of the larger stones have passed ; without their help the present notes could not have been written, and I therefore desire to express to them my hearty thanks.