CONTENTS. 
iii 
Art. XXX. Historical Account of Discoveries respecting the 
Double Refraction and Polarisation of Light : 
Period II. Discoveries of Huygens, - 16? 
XXXI. On a Singular Developement of Crystalline Struc- 
ture by Phosphorescence, - 171 
XXXII. Some Account of Professor Amici’s Discoveries 
relative to the Motion of Sap in Plants, 172 
XXXIII. Mineralogical Report made by the Chief Engi- 
neer of the Grand Duke of Tuscany to his Se- 
rene Highness, respecting the Island of Elba, 1 77 
XXXIV. Quarterly Abstract of the Diurnal Variation of 
the Magnetic Needle. By Colonel Beaufoy, 
F. R. S. - - 179 
XXXV. Proceedings of the Royal Society of Edinburgh, ib. 
XXXVI. Proceedings of the Wernerian Natural History 
Society, - - 181 
XXXVII. Scientific Intelligence, - 182 
I. natural philosophy. 
Astronomy. 1. Comet of I8I9. 2. Elements of the Or- 
bit of the Planet Ceres. 3 . Elements of the Orbit of 
the Planet Juno. 4. Geocentric Places of Pallas. 5. Ba- 
ron Zach on the Error of Repeating Circles, - 1S2 
Optics, 6 . Inclination of the Resultant Axes of Crystals. 
7. Crystals with one Axis of Double Refraction. 8. Re- 
fractive power of Hyposulphate of Soda and Silver. 
9. Refractive power of Nitrite of Lead. 10. Mr Brande 
on the illuminating power of Gases, - 183 
Magnetism. 11. Captain Scoresby on the Anomaly in 
the Variation of tlfe Needle, - 184 
Meteorology. 12. Sir H. Davy’s Theory of Mists, 18^ . 
II. chemistry, 
13. New Alkali discovered by MM. Pelletier and Caventou 
in the Veratrum Sabadilla. 14. Dr Clarke on the Alloy 
of Lead and Platinum. 15. Experiments on Rock-crys- 
tal and Glance-coal exposed to the Heat of the Alloy of 
Tin and Platinum. I6. Boracic Acid found in the Crater 
of Vulcano. I7. Improvement on the Gas Blowpipe. 
18. Purpuric Acid. I9. Specific Gravity of the Alloy of 
Tin and Platinum, 20. Economical Scales for Thermo- 
meters, ^ . 185—1851 
III. natural history. 
Mineralogy. 21. American Tourmalines. 22. Cave of 
.plephanta, 23, Jameson’s Mineralogy. 24. Vitreous 
