[FOR THE USE OF MEMBERS. | 
Royal Fustitution of Great Britain. 
1851. 
WEEKLY EVENING MEETING, 
Friday, March 28. 
Witiiam Pots, Esa. M.A. F.R.S. Treasurer, in the Chair. 
Nevit Srory Masxetyne, Esq., M.A. 
On the Connexion of Chemical Forces with the Polarization of Light. 
Any facts which can throw light upon the ultimate molecular 
structure and condition of chemical compounds, cannot fail of pos- 
sessing interest of a high character, as well for those whose 
thoughts only casually dwell upon questions of physical science, as 
for the mathematician and the chemist. To the mathematician, 
indeed, they would, if completely unfolded, supply the data for him 
to undertake the resolution of the questions of chemical combination 
and chemical change, by treating them as problems involving the 
action of mechanical laws; to the chemist, the acquisition of such 
knowledge would be the removal of some of the profoundest diffi- 
culties of his philosophy : but such knowledge is only to be sought 
in the most difficult paths of the whole range of science. The 
question of the connexion of chemical type with crystalline form, 
the fruitful cause of so much contention among mineralogists as to 
the questions of mineral species, is one on which we have no com- 
plete and sure knowledge; for the facts of dimorphism show, that 
implicated with this question are the actions of other forces, such as 
electric condition, and above all the mysterious molecular alterations 
induced by heat. Another direction in which such inquiries have 
been pursued, has been in tracing the phenomena resulting from the 
property possessed by many bodies, of modifying a plane-polarized 
ray of light, by what is termed circular-polarization. This property, 
from its being proved to be, ina large number of cases, an expression 
of the molecular structure of the substance, and as such inseparable in 
many cases from its chemical existence, may be taken, whenever 
this can be shown to be the case, as an evidence of its individuality, 
and may be used to determine the question of the permanency or 
transitory character of the molecular type of the substance. The 
information thus gained may be but vaguely defined, and the truth 
but darkly seen, yet does it nevertheless afford a valuable and 
interesting point of view for studying the molecular nature of bodies, 
No, 4. E 
