CONTENTS of N° 20.— New Series. 



XII. On Websterite found in the Plastic Clay of Auteuil, near 

 Paris. By M. Alexandre Brongniart, Member of the Royal 

 Academy of Sciences, and Professor of Mineralogy at the Jardin du 

 lloi, Paris page 81 



XIII. On the Phenomena of Volcanoes. By Sir Humphry Davy, 

 Bart. F.R.S 85 . 



XIV. Rationale of the Difficulty of separating Plane Surfaces by 

 a Blast, in certain Cases. By R. Hare, M.D. Professor of Chemistry 



in the University of Pennsylvania 94 



XV. Chemical Examination of the Oxides of Manganese. By 

 Edward Turner, M.D. F.R.S. Ed. Professor of Chemistry in the 

 University of London, and Fellow of the Royal College of Physicians 



of Edinburgh 96 



XVI. General Solution of the Problem: to represent the Parts of 

 a given Surface on another given Surface, so that the smallest Parts 

 of the Representation shall be similar to the corresponding Parts of 

 the Surface represented. By C. F.Gauss. Answer to the Prize 

 Question proposed by the Royal Society of Sciences at Copenhagen. 



( To be continued) : 104* 



XVII. Analysis of two new Mineral Substances, consisting of Bi- 

 seleniuret of Zinc and Sulphuret of Mercury, found at Culebras in 

 Mexico. By Professor Del Rio 113 



XVIII. Observations on the Peruvian Andes, in reply to a Paper 

 by M. Coquebert de Montbret, in the Annates des Sciences Naturelles. 



By J. B. Pentland, Esq 115 



XIX. On the Penetration of Water into stoppered and corked 

 Bottles sunk to a great Depth in the Sea. By J. de C. Sowerby, Esq. 

 F.L.S. &c. 119 



XX. Some further Remarks on Messrs. Tiedemann and Gmelin's 

 Observations on the Acids of the Stomach. By Wm. Prout, M.D. 

 F.R.S 120 



XXI. On the vitrified Fort of Dunnochgoil, in the Isle of Bute. 



By Samuel Sharpe, Esq. F.G.S 123 



XXII. Method of solving adfected Quadratic Equations. By Mr. 

 Joseph Seers; in a Letter to Mr. Peter Nicholson 125 



XXIII. Improved Eudiometrical Apparatus. By R. Hare, M.D. 

 Prof, of Chemistry in the University of Pennsylvania. (To be continued.) 126 



XXIV. Notices respecting New Books: — Pearson's Appendix to 

 the First Volume of an Introduction to Practical Astronomy ; — Har- 

 wood on the Curative Influence of the Southern Coast of England 134? — 136 



XXV. Proceedings of Learned Societies: — Astronomical Society ; 

 Royal Academy of Sciences of Paris 136 — 141 



XXVI. Intelligence and Miscellaneous Articles : — New Astro- 

 nomical Ephemeris ; Improved Air-pump, by Mr. John Dunn, Op- 

 tician, Edinburgh; Gallates ofQuina and Cinchonia ; Preparation 

 and Properties of Aluminum; Chloride and other Compounds of 

 Aluminum ; Native Iodide of Mercury ; Corydalin, a new Vegetable 

 Alkali ; Action of Alkalies and their Carbonates, &c. on Iodides ; 

 Citric Acid from Gooseberries ; Solanine ; Blue Colour by the Action 

 of Muriatic Acid upon Albumen ; Botryogene, or Native Red Iron- 

 Vitriol of Fahlun ; Erinite, a new Mineral Species ; Alteration of 

 Crystalline State in Solids ; Decomposition of Ammonia by Metals ; 

 Iodides of Carbon ; Solar Spots ; New Patents ; Mr. Herapath ; 

 Meteorological Observations; Table, &c 141 — 160 



• # * It is requested that all Communications for this Work may be addressed, 

 post paid, to the Care of Mr. R. Taylor, Printer, Red- Lion-Court, Fleet- 



