Jj CONTENTS. 



Page 



XV. CONTRIBUTIONS TO POPULAR SCIENCE, . 85 



No. V. On the Invisibility of certain Colours to Certain Eyes, - ib. 

 No. VI. Description of the Thaumatrope, - - 87 



No. VII. Singular Optical Illusion seen through a Telescope, - 88 



No. VIII. Variation of the Optical Deception of Le Cat, 89 



No. IX. Optical Illusion in examining a Dioramic Picture, - 90 



XVI. On the Quartz District in the Neighbourhood of Inverness. (Con- 

 cluded from Vol. III. p. 218.) By George Anderson, Esq. F. R. S. E., 

 F. S. S. A. and Secretary to the Northern Institution for the Promotion 



of Science and Literature at Inverness. Communicated by the Author, 91 



XVII. Description of the Bituminous Rock which occurs in Ross-shire, and 

 the neighbourhood of Inverness, &c. By George Anderson, Esq. 



F. R. S. E., &c. Communicated by the Author, - 93 



XVIII. Description of an inverting Sextant Telescope with Nautical Eye- 

 Tube, for taking Altitudes at Sea when the Horizon is Invisible. In- 

 vented by Mr Mathew Adam, A M. Rector of the Academy of Inver- 

 ness. Communicated by the Author, .... 95 



XIX. On the Optical Illusion of the Conversion of Cameos into Intaglios, and 

 of Intaglios into Cameos, with an Account of other Analogous Pheno- 

 mena, ----- - - 99 



XX. Analysis of Picrosmine. By Gustavus Magnus, Esq. of Berlin. 

 Communicated by the Author, - « 103 



XXI. On the Means ot' Detecting Lithia in Minerals by the Blowpipe. By 

 Edward Turner, M. D. F. R. S. E. &c. Lecturer on Chemistry, and 

 Fellow of the Royal College of Physicians, Edinburgh. Communicated 



by the Author, - - - ll3 



XXII. On the Apparent Direction nf F.yps in a Tortrait. By W. H. Wol- 

 lastow, M. D. F. R. S. and V. P. With a Plate, - - 117 



XXI II. On the Vegetable Productions of the Island of Madeira. By Dr H. 

 Khul, - - - - - - - 119 



XXIV. CONTRIBUTIONS TO METEOROLOGY, - - 124 



1. On the Negative Electricity of Showers. By Mr John Foggo, ib. 



2. Account of an Improved Hygrometer, - - 127 



XXV. Account of the Discoveries and Experiments of the Swedish Chemists 

 during the year 1 825. Drawn up for this Journal by a Correspondent at 

 Stockholm, - - - - - • 128 



1. Professor Berzelius's Discovery of Lithia in Mineral Waters, ib. 



2. Professor Berzeliu/s Experiments on the Orange Gas produced from 



a mixture of Fluor-Spar and Chromate of Lead, - - 129 



3. Account of Professor Berzelius's Method of Detecting Arsenic in the 

 Bodies of Persons Poisoned, ... - 131 



4. Professor Berzelius's Researches on Molybdaena, - - 133 



5. M. Setterberg's Experiments on the Sulphurets of Cobalt, - 130 



6. M. Mosander on the Precipitation of Magnesia by Carbonate of 

 Soda, - - - - ib. 



7. M. Mosander's Analyst of the Oxides of Iron, formed by continued 

 Heat, ...... . 137 



XXVI. On some Remarkable Concretions which are found in the Sandstone 

 of Kerridge in Cheshire. By Samuel Hibbert, M. D. F. R. S. E. and 



