“—_ 
CONTENTS. 
XXXVII. On the Optical Phenomena and Crystallisation of Towrmaline, 
Titanium, and Quartz, within Mica, Amethyst, and Topaz. 
By Sir Davin Brewster, K.H., D.C.L., F.R.S., and 
V.P.R.S. Edin. (With a;Plate.) ‘ 
XXXVIII. On the Production of Crystalline Structure in Orystallised Pow- 
ders, by Compression and Traction. By Sir Davip BREWSTER, 
K.H., D.C.L., F.8.8., V.P.R.S. Edin. 
XXXIX. On the Absolute Zero of the Perfect Gas Thermometer ; being a 
Note to a Paper on the Mechanical Action of Heat. By Wm. 
J. M. RAnkKInge, C.E., F.R.S.E., F.R.S.8.A., &c. 
XL. On the Mechanical Action of Heat. By Wm. J. M. Ranking, 
C.E., F.R.S.E., F.R.S.8.A., &c., : : 
XLI. On Nitric Acid as a Source of the Nitrogen found in Plants. By 
GEORGE Witson, M.D., 
XLII. Some Observations on Fish in relation to Diet. By Joun Davy, 
M.D., F.R.S. Lond. & Ed., Inspector-General of Army Hos- 
pitals, f : 3 A : , 
XLII. On Circular Crystals. By Sir Davip Brewster, K.H., D.C.L., 
F.R.S., and V.P.R.S. Edin. (With Two Plates.) : 
Proceedings at Statutory General Meetings, Sc., 
List of the present Ordinary Members, in the order of their Baesias: 
Last of Ne on-Resident and Foreign Members, elected ander the Old Laws, 
| Honorary Fellows, 
Fellows Deceased, ee ead: or Canes un 1349 to 1853, 
Public Institutions, Sc., entitled to receive the Transactions and Proceedings 
of the Society, 
Last of Donations, continued from Vol. x VI, page 648, 
Index, : 
Laws of the Bieta, 
VOL. XX. c 
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