CON T E X TS. 



Art. XX. — Transition Temperature of Sodic Sulphate, a 



New Fixed Point in Thermometry ; by T. W. Richards 201 



XXI. — Distribution and Quantitative Occurrence of Vana- 

 dium and Molybdenum in Rocks of the United Stat< 

 by W. F. Hillejjkam' 



XXII. — Electrosynthesis ; by W. G. Mixter 217 



XXIII. — Notes on Species of Ichthyodectes, including the 

 new species I. cruentus, and on the related and herein 

 established genus Gillicus ; by O. P. Hay 225 



XXIV. — Determination of Manganese as the Pyrophosphate; 



by F. A. Goocn and M. Austix 233 



XXV. — Occurrence of Dunite in Western Massachusetts; 



by G. C. Martin _ .. _ 244 



XXVI. — Origin and Significance of Spines : A Study in Evo- 

 lution; by C. E. Beecher _ 249 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics— Laboratory Guide m Qualitative Chemical Analysis, H. 

 L. Wells: Short Course iu Inorganic Qualitative Analysis for Engineering 

 Students, J. S. C. Wells: Introduction to Electro-chemical Experiments, F. 

 Oettel, 269. — Remarks on Colloidal Glass, C. Barus, 270. 



Geology and Mineralogy — Late Formations and Great Changes of Level in 

 Jamaica, J. W. Spencer, 270. — Resemblance between the Declivities of High 

 Plateaus and those of Submarine Antillean Valleys, J. W. Spencer, 272. — 

 Eruptivgesteine des Kristianiagebietes, Part III, W. C. Brogger, 273. — Bad- 

 deckite, a new variety of Muscovite, G. C. Hoffmann, 274. — Text Book of 

 Mineralogy with an extended Treatise on Crystallography and Physical Miner- 

 alogy, E S. Dana, 275.— L'or dans la Nature, E. Cumenge and F. Robellaz, 

 276. 



Botany — Illustrated Flora of the Northern States and Canada, N. L. Britton 

 and Addison Brown, 27 7. 



Obituary— Professor James Hall, 284. 



