CONTENTS. 
XVII. Observations on the Principle of Vital Affinity, as illustrated by recent 
discoveries in Organic Chemistry. By Witi1AM PULTENEY ALI- 
son, M.D., F.R.S.E., Professor of the Practice of Medicine in the 
University of Edinburgh, 
XVIII. Account of some Experiments on the Temperature of the Earth at dif- 
ferent Depths, and in different Soils, near Edinburgh. (With Four 
Plates.) By James D. Forses, Esq., F.R.S., Sec. R.S. Ed., &c. 
Corresponding Member of the Institute of France, and Professor 
of Natural Philosophy in the University of Edinburgh, 

PART III. 
XIX. On a Formula representing the Mean Height of the Barometer at the 
Level of the Sea. By Professor HANSTEEN of Christiana, in a 
Letter addressed to Professor ForBrs, Secretary of the Royal 
Society of Edinburgh, 
XX. On General Differentiation. Part III. By The Rev. P. Kenuanp, 
M.A., F.R.SS. L. & E., F.C.P.S., late Fellow of Queen’s College, 
Cambridge, Professor of Mathematics, &c., in the University of 
Edinburgh, 
XXI. Observations on the Principle of Vital Afinity, as dlustrated by re- 
cent discoveries in Organic Chenustry. By WiLLiAM PULTENEY 
Aison, M.D., F.R.S.E., Professor of the Practice of Medicine in 
the University of Edinburgh. Part IT. 
XXII. An Attempt to Hlucidate and Apply the Principles of Goniometry, as 
published by Mr WARREN, im his Treatise on the Square Roots of 
Negative Quantities. By The Right Rev. Bishop Terror, 
XXIII. On the Reaction of Natural Waters with Soluble Lead Salts. By 
ARTHUR CONNELL, Esq., F.R.S.E., Professor of Chemistry in the 
University of St Andrews, 
XXIV. On certain Products of Decomposition of the Fixed Oils in contact with 
Sulphur. By Tuomas ANDERSON, Esq., M.D., F.R.S.E., Lecturer 
on Chemistry, Edinburgh, : , 
Vil 
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