MINERALOGY. 259 



The presence of hydrogen shows that the mineral should be removed 

 from the group of anhydrous silicates. F. "W. R. 



Sismonda/ — . Element! di storia naturale. Mineralogia. [Minera- 

 logy.] Turin. 



Sjogren, Ant. Mineralogiska notiser. [Mineralogical Notes.] 

 Geol. Foren. Stoclcholm Forhandl. Bd. ii. pp. 407-410. 



i. A peculiar form of hornblende crystal (with figures), ii. Dis- 

 covery of Scheelito in IN'ordmark. iii. Occurrence of Pyrosmalitc in 

 Nordmark mines. G. A. L. 



. Observationer rorande kromjernets moderklyft. [The 



Matrix of Chrome-iron.] Geol. Forea. Stoclcholm Forhandl. Bd. ii. 

 no. 27, pp. 551-555. 



Smith, Prof. J. L. TroVlite ; sa vraic place mineralogique et 

 chimique. [Troilitc, its True Position mineralogically and chemi- 

 cally.] Compt. Rend. t. Ixxxi. pp. 976-978. 

 Two analyses are given, as well as new physical details respecting 

 troilite, bearing out the author's opinion (opposed by M. St. Meunier) 

 that this mineral is truly meteoric, and not to be confounded with 

 pyrrhotine. G. A. L. 



Smyth, W. W. The Ores of Iron considered in their geological 

 relations. Journ. Iron Sf Steel Inst. pp. 43-54 ; Discussion, 54- 

 59 ; with woodcut. Also Iron, vol. v. p. 714. 



Mineralogical descriptions of the principal ores of iron, with remarks 

 on their mode of occurrence. 



. Six Lectures on Mineralogy. Coll. Guard, vol. xxix. pp. IGG, 



201, 227, 272, 311, and Min. Journ. vol. xlv. pp. 218, 247, 270, 

 298, 327, 354. 



Abstracts of a course of lectures at the Museum of Practical Geology. 



Sohncke; L. Ueber Aetzfiguren an Steinsalzwiirfoln, und iiber 



die von F. Exner angewandte Methode zur Erzeugung vou 



Losungsfiguren. [On Etched Figures on Rock-salt, and on Exner's 



Method.] N. Jahrb. Heft ix. pp. 938-942. 



Compares the methods of Leydolt and Exner for producing these 



erosion-figures, and adduces reasons for preferring the former. Describes 



his own experiments, and gives measurements of figures etched on 



rock-salt. These represent various pyramidal cubes ; but the author 



never obtained the form (« :2a: cc a), which had been described by 



Leydolt. The measurements were only approximate ; and it is probable 



that the figures cannot be strictly referred to any definite j^yramidal 



cube. F. W. R. 



Spring, W. Hypothi-ses sur la Cristallisation. [Hypotheses on 

 Crystallization.] Ann, Soc. Geol, Behj. t. ii. Memoires, pp. 131- 

 177. 



These hypotheses are chiefly based on a consideration of the relations 



b2 



