Royal Society. 35 
in a very masterly style: equal, if not superior, to those of his 
History of Quadrupeds and of British Birds. 
Dr. E. D. Clarke has in the press a Treatise entitled ‘“‘ The 
Gas Blow Pipe, or Art of Fusion by burning the Gaseous 
Constituents of Water;” giving the History of the Philosophical 
Apparatus so denomiuated ; the Proofs of Analogy in its Opera- 
tions to the Nature of Voleanoes; together with an Appendix 
containing an Account of Experiments with this Blowpipe. 
XII. Proceedings of Learned Societies. 
ROYAL SOCIETY. 
Nov. 5, 1818. Taz Croonian Lecture was read by Sir E. Home. 
It had for its subject the conversion of Pus into granulations of 
newFlesh. According to Sir Everard, granulations which appear 
to consist of a congeries of tortuous vessels, are formed in a way 
similar to the blood-vessels, as described by him in a former pa- 
er*, Pus, wheu first secreted, is a transparent fluid, a pellicle 
of which, in this state, covers the little prominences of the gra- 
nulations. Under this pellicle particles of air (supposed to be 
carbonic acid) are exuded, upon which vessels seem to be 
moulded, which soon become distended with the red blood. 
They chiefly lie horizontally, and minute red spots are also visi- 
ble, supposed to be the terminations of vessels running in a perpen- 
dicular direction. This paper was accompanied with drawings. 
Nov. 12. A paper “ On the Laws which regulate the Absorp- 
tion of polarized Light by doubly refracting Crystals,’’ by Dr. 
Brewster, was read. He was led to this investigation by ob- 
serving the phenomena presented by the acetate of copper when 
exposed to polarized light. The paper treats first of the ab- 
sorption of polarized light by crystals of one axis; and, secondly, 
by crystals having more than one; and concludes with remarks 
on the effects of heat in modifying the absorption of polarized 
light by crystallized bodies. Heat does not, as is generally 
posed, produce the pink colour of some topazes, but discharges 
the yellowish colouring matter of one medium, leaving the pink 
colouring matter of another, and which originally existed in it. 
The author seems to be of opinion, from his experiments, that the 
colouring particles of crystals are confined to different media, and 
are not dispersed indiscriminately throughout their mass, as is 
commonly believed. 
* Phil. Trans. 1818, Part I. 
D4 The 
