Meteorology. — Chemistry. ^Ol 
Sir George Mackenzie, Bart. Convener. 
Dr Hope, Patrick Neill, Esq. 
Professor Jameson. Robert Stevenson, Esq. 
Alex. Irving, Esq. Dr Brewster. 
We trust that the members of the Royal Society, and lovers 
of science in every part of the world, will second the endeavours 
of this committee, to obtain information so useful to their coun- 
try, and to the general progress of knowledge. 
10. On the Cause of Regular Figures formed hy Itoar^ 
Frost on Windows. curious phenomenon was ascribed by 
M. Mairan to the pre-existence in the glass of certain regular 
figures arid lines generated during its formation, and he supposes 
that the particles of hoarfrost deposit themselves according to these 
figures. M. Carena, in a memoir Sur le Givre figuree.^ published 
in the Memoires de Turin for 1813 and 1814, p. 56. — 79. has 
overturned this hypothesis, and shews that the following are among 
the principal causes of the phenomenon. 1. The natural force 
of crystallization. 2. The necessity of the hoar-frost extending 
itself along a plane surface, which restrains the quaquaversus 
tendency of crystallization. 3. The numerous and varied re- 
sistances presented by the surface of the glass. 4. The imper- 
fect and irregular conducting power of the glass, which is apt to 
produce in the vapours curvilineal motions at the instant pre- 
ceding their congelation. M. Carena placed a small copper disc 
on the outside of one of the panes of glass, and found that the 
corresponding part of the glass was always free from hoar-frost, 
II. CHEMISTRY. 
11. Carbonic Jcid^ i^c. found in Sea-Water. — M. Vogel has 
remarked, that Dr Murray and Dr Marcet have regarded sea- 
water as more simple than it really is ; and that he has evidence, 
that the waters of the Mediterranean and the ocean contain 
carbonic acid and also carbonates of lime and magnesia. JoUrn. 
de Pharmacies tom vi. p. 378* 
Is. Muriate of Potash in RocJc-Salt. — M. Vogel has disco- 
vered muriate of potash in the rock-salt of Berchtesgaden, in 
Upper Bavaria, and in that of Hallein in Salzburg. When 
dissolved in water, and freed, by evaporation, of the greater 
