CONTENTS. 
XXVII. On the state of water and aeriform matter in cavities 
found in certain crystals . By Sir Humphry Davy, Bart. 
P . R. S. p. 367 
XXVIII. Some experiments on the changes which take place in 
the fixed principles of the egg during incubation . By William 
Prout, M. D. F. R. S. p. 377 
XXIX. On the Placenta. By Sir Everard Home, Bart. 
V. P. R. S. p. 401 
XXX . Of the geographical situation of the Three Presidencies , 
Calcutta, Madras, and Bombay, in the East Indies. By J. 
Goldingham, Esq. F. R. S. p. 408 
XXXI. Of the difference of longitudes found by chronometer, and 
by correspondent eclipses of the satellites of Jupiter ; with some 
supplementary information relative to Madras, Bombay, and 
Canton ; as also the latitude and longitude of Point de Galle 
and the Friar’s Hood. By J. Goldingham, Esq. F. R. S. 
P- 43 1 
XXXII. Observations on the genus Planaria. By J. R. Johnson, 
M. D. F. R. S p. 437 
XXXIII. Some experiments and researches on the saline contents 
of sea-water, undertaken with a view to correct and improve 
its chemical analysis. By Alexander Marcet, M.D. F.R.S. 
Honorary Professor of Chemistry at Geneva. p. 448 
XXXIV. On the ultimate analysis of vegetable and animal sub- 
stances. By Andrew Ure, M. D. F. R. S. p. 457 
Presents received by the Royal Society from November , 1821, to 
July, 1822. p. 483 
