238 MINERALOGY. 



Rammelsberg, C. Ueber die Zusammensetzung des Leukophans 



und des Melinophans. [Leucophane and Melinophane.] Zeitsch. 



deutsch. geol. Ges. Bd. xxviii. Heft 1, pp. 57-63 ; and Monatsh. 



Tc. preuss. AJc. Wiss. pp. 22-26. 



The rarity of melinophane has hitherto prevented fresh analyses ; 



it is shown that glucina was mistaken for alumina : new results give 



percentages from which is deduced the formula 



6NaFl + 7{^|05.}, 



while that of leucophane from new analyses is declared to be 



6Xari+|j^,g.Q, 3|. ^^^ 



. Ueber Aerinit und Ginilsit. Zeitsch. deutsch. geol. Ges. 



Bd. xxviii. Heft 2, pp. 234-237. 



Aerinite, a homogeneous mineral, avowedly from Aragon. Sp. gR 

 2-671. Analysis suggests the formula 21iSi03 . ll2SiO^, the basis being 

 lime, magnesia, ferrous and ferric oxide, and alumina. Of Ginilsite, 

 from the Grinilsalp (Grisons) a new analysis is here given. E. B. T. 



. Ueber die Zusammensetzung des ISTephelins. [Composition of 



Nepheline.] Monatsh. Tc. preuss. Ak. Wiss. pp. 695-703. 



Ramsay, William. On Bismuthiferous Tesseral Pyrites. Journ. 

 Chem. Soc. ser. 2, vol. xiv. pp. 153, 154. 



Small metallic crystals from an unknown locality, and too small to 

 be measured, were analyzed and found to contain 37*64 p. c. of bismuth. 

 The formula of the mineral is (Ni, Co, re)(A8, Bi), ; and its sp. gr. 

 7-55. ■ ' F. W. K 



Rath, G. vom. Zwillingverwachsung der triklinen Feldspathe nach 

 dem sogen. Periklin-Gesetze und iiber eine darauf gegriindete 

 Unterscheidung derselben. [Twinning of Triclinic Felspar.] 

 Monatsh. h. preuss. Ah. Wiss. pp. 147-174, plate. 



Crystallographic description, with analyses by the author. Prof. A. 

 Koch, and others. 



. Die Zwillingsverwachsung der triklinen Feldspathe nach 



dem sogen. Periklin-Gesetze und liber eine darauf gegriindete 



Unterscheidung derselben. [Twin -growth of Triclinic Felspar 



according to the " Pericline Law," &c.] iV. Jahrb. Heft vii. pp. 



689-715 ; plate and 2 woodcuts. Also in Monatsh. h. Ah. Wiss. 



Berlin., Feb. 



Various views have been held with respect to the law of twinning 



in pericline. The author confirms Mobs and Breithaupt in their 



expression of the law, axis of rotation parallel to the macrodiagonal. 



Describes peculiar double twins of albite formed according to this law. 



