230 MINEEALOGT. 



corundum, topaz, and diamond. Suggests that diamonds may have 

 been formed by the action of reducing agents on very highly compressed 

 carbon dioxide at temperatures above its critical point. E. W. R. 



Hartley, W. N. The Identification of Liquid Carbonic Acid in 

 Mineral Cavities. 3Iicr. Journ. vol. xv. pp. 170-175, pi. 132. 



It being known that liquid carbonic acid becomes a gas at a tempe- 

 rature of 30°-92 C, various sections of crystals with fluid- cavities were 

 examined by first heating to a certain temperature, and then observing 

 under the microscope whilst cooling. Prom repeated experiments the 

 author concludes that many such cavities contain liquid carbonic acid. 

 An explanation of the appearance of boiling exhibited by the fluid in 

 these cavities is also given. E. T. N. 



Hawes, Gt. W. Contributions from the Shefiield Laboratory of Yale 



College. — No. XL. On a Lithia-bearing variety of Biotite. Amer. 



Journ. ser. 3, vol. xi. pp. 431, 432. 



This biotite is from the felspar- quarries of Portland, in Connecticut. 



Two analyses are given, showing that the mica is an iron-biotite, in 



which part of the potash is replaced by lithia, and containing more 



ferrous oxide and less magnesia than usual. G. A. L. 



Heddle, Prof. Chapters on the Mineralogy of Scotland. Chap. 1st. 



The Khombohedral Carbonates. Part I. Trans. R. Soc. JEdin. 



vol. xxvii. pt. 4, p. 493. 



Notes and analyses of the following minerals : — ankerite, breunnerite, 



dolomites (various), variously coloured calcites. Concludes with notes 



on dolomite pseudomorphous after scaleuohedra of calcite from trap tuft' 



at Kinkell, near St. Andrews. E. E., Jun. 



Helland, A. Om Kogsaltkrystaller og flydende Kulsyre i et og samme 



HuUrum i Kvarts fra en Pegmatitgang. [On Crystals of Sodic 



Chloride and Eluid Carbonic Acid in the same Cavity in Quartz from 



a Vein of Pegmatite.] Arch. Math. Naturvid. pp. 6, 5 figs, in text. 



Microscopic description. The writer's observation, that crystals of 



sodic chloride occur in cavities which also contain fluid carbonic acid, 



tends to throw light on the nature of the so-called " outer zone " which 



is known to separate the carbonic acid from the surrounding quartz in 



many carbonic acid cavities. E. E. 



Helmkacker, R. Pyrit von Waldenstein in Karnthen. [Pyrites 



of Waldenstein, in Carinthia.] Min. Mitth. Heft i. pp. 13-24; 



2 plates. 



A crystallographic memoir. 202 crystals have been studied, and the 



following new forms have been detected : — tt (940), tt (180), (433), 



(322), n (532), TT (742), n (13-73), tt (14-11-10), tt (13-96), tt (314). 



E. W. R. 



. Mineralogische Beobachtungen aus dem ostlichen Bohmen. 



