CONTENTS. 
X. On some phenomena of colours, exhibited by thin plates. By 
John Knox, Esq. Communicated by the Right Hon. Sir Joseph 
Banks, Bart . G. C. B. P. R. S. - 161 
XI. Some farther observations, on the current that often prevails, 
to the westward of 'the Scilly Islands. By James Rennell, 
Esq.F.R.S. - 182 
XII. Some experiments on a solid compound of iodine and oxygene, 
and on its chemical agencies. By Sir Humphry Davy, LL.D. 
F. R. S. - - - - 203 
XIII. On the action of acids on the salts usually called hyperoxy- 
muriates, and on the gases produced from them. By Sir 
Humphry Davy, LL.D. F. R. S. - - 214 
XIV. Farther analytical experiments relative to the constitution of 
the prussic, of the ferruretted chyazic, and of the sulphuretted 
chyazic acids ; and to that of their salts ; together with the appli- 
cation of the atomic theory to the analyses of those bodies. By 
Robert Porrett^zm. Esq. Communicated by W . H. Wollaston, 
M. D. Sec. R. S. - - - 220 
XV. On the nature and combinations of a newly discovered vege- 
table acid; with observations on the malic acid, and sugges- 
tions on the state in which acids may have previously existed 
in vegetables. By M. Donovan, Esq. Communicated by 
W. H. Wollaston, M. D. Sec. R. S. - 231 
XVI. On the structure of the organs of respiration in animals 
which appear to hold an intermediate place between those of the 
class pisces and the class vermes, and in tzvo genera of the last 
mentioned class. By Sir Everard Home, Bart. V. P. R. S. 256 
