70 An unlverfal volatile acid Spirit , 
are always 'hexangular, or with fix Points 
nearly refembling the Bafe of the Column 
of Nitre i, or thin Slices of fuch a Column 
cut off trail werfely : and as freezing is ufually 
imputed to the Redundance of Nitrous Par¬ 
ticles in the Air, thofe who embrace that 
Opinion will probably find little Difficul¬ 
ty in fuppofing this Form of Snow occa- 
fioned by the fame Principle that gives an 
hexagonal Figure to Nitre: and perhaps 
they are not miftaken in fuch a Suppofition, 
though there is fome Reafon to believe they 
may be fo as to the Abundance of the Par¬ 
ticles of Nitre they imagine exifling in the 
Air* 
The continual Perforation of growing 
Vegetables; the Putrefaction and DiiTolution 
of thofe that perifh over the Face of the 
whole Earth, all which abound with vola¬ 
tile acid Salts ; the continual Exhalations 
from Seas, Lakes, Rivers, and other Waters, 
which carry alfo up with them Abundance 
of the fineft Particles of Mineral or Sea 
Salts; the Steams and Vapours from Metals 
and other Subfiances: all thefe compofe to¬ 
gether the volatile acid Spirit wherewith the 
Air is filled, and which probably is the ac¬ 
tive Principle that gives the Figure, and 
fupplies Part of the Matter to Cryflals* 
Snow, and Nitre. 
* The Flakes found now and then with twelve Points, are 
probably two Flakes, whofe fiat Surfaces are ftack together, 
with their Rays alternately aifpofed. 
But 
