I 
-jj. .. A* vw i f ‘ • »' i 
64 Cryjlah of Nitre? how obtained . 
Iiified according to my Method of Exami¬ 
nation* though indeed lefs than what may be 
found when large Quantities are prepared in 
the common Way $ and confift of fix pa¬ 
rallel Sides or Planes, which compofe Bo¬ 
dies of different Lengths* and differently 
terminated at the Ends, There is alfo a 
confiderable Variety as to the Equality and 
Inequality of thefe fix Sides. The mod 
common Crydals are fometvhat flat, and 
have two broad parallel Planes oppolite td 
one another, and four that are much nar¬ 
rower ; two of which (viz . one that goes 
Hoping from the upper, and the other from 
the under Plane) meet on each Side* and 
conditute a pretty fharp Edge. One End 
of thefe is commonly cut off Hoping oil 
both Sides along its whole Breadth, but 
feldom in the fame Angle. Vid. Fig. i. 
■ Sometimes however there are four broader 
Planes* and only two narrower; and now 
and then the Sides are pretty equal, and 
their Safe is nearly an equilateral Hexagon. 
The feveral Differences in tile Drawing are 
likewife to be met with, as well as forne 
others, but the rareil as well as the prettied: 
is that at Fig. 6i 
The bed Way to obtain thefe Cryflals for 
the Microfcope, is by faturating fome warn! 
Water in a Spoon with Nitre (not with 
more however than it can perfectly diffolve)^ 
When in a few Minutes little Concretions 
will 
