viii CONTENTS. 



SUPPLEMENT TO VOL XX. 



Engravings of the following Objects: 1. Compound Sulphuret: 2. New Pro- 



Eerties of Tangents: 3. Radiation and Kdlection ot Cold: 4. Mr. Richard 

 )rew's Balance Level: 5. Mrs. D'Oj ley's Method of rearing Poultry. 



L The Bakerian Lecture on some new Phenomena of Chemical Changes pro- 

 duced by Electricity ; particularly the Decomposition of the fixed Alkalis, 

 and the Exhibition of the new Substances which constitute their Bases; and 

 on the general Nature of Alkaline Bodies. By Humphry Davv, Esq. Sec. 

 R.S. M.R.LA. - - - - - 3'2i 



II. On the Composition of the Compound Sulphuret from Huel Boys, and zn 

 Account of its Crystals. By James Smithson, Esq. F. R. S. - 332 



III. On a new Property of the Tangents of the three Angles of a Plane Trir 

 angle. By Mr. William Garrard, Quarter Master of Instruction at the Royal 

 Naval Asylum at Greenwich. Communicated by the Astronomer Royal 338 



IV. On a new Property of the Tangents of three Arches trisecting the Circum- 

 ference of a Circle. By Nevil Maskelyne, D. D. F. R. S. and Astronomer 

 Royal - - - - - - 3-40 



V. On the apparent Radiation and Reflection of Cold by Means of two con- 

 cave metallic Mirrors. In a Letter from Mr. John Martin - 34 i 



YE Description of a Balance Level, useful for laying out Land for Irrigation, 

 for Roads, and other Purposes. By Mr. Richard Drew, of Great Ormon(l 

 Street - - - - - - 34-t 



VIE Account of a new Method of rearing Poultry to Advantage. By Mrs. 

 Hannah D'Oyley, of Sion Hill, near Northallerton, Yorkshire 340 



VIII. Communication from the Right Hon, the Earl of Fife, relative to his 

 Plantations - - - - - - 330 



IX. Remarks on the Advantages derived from Plantations of Ash Trees. Br 

 David Day, Esq. of West hill, near Rochester - - 352 



X. Chemical Examination of a Sparry Iron Ore, sent to Mr. Guyton by Berg- 

 man. By Mr. Collet-Descotils - - - 357 



XL Chemical Examination of the Alum Ore of Tolfa, and the Earthy Alu- 

 minous Schist of Freienwald. By Mr, Klaproth - - 339 



XII. On the Effects of Galvanism on Aninvils. In a Letter from Mr. John 

 Tatum - - - - - - 371 



XIII. On the Structure and Uses of the Spleen. By Everard Home, Esq. 

 F.R.S. - - - - - - 374 



XIV. On the Purificatigu of Lemon Juice. In a Letter from a Correspondent 



382 



Scientific News - -' - - 383 



