Dr Gindin's Analysis of' Finite 
of pinite contain, therefore, 019735 grains of potash — 7*894 
per cent., and 0-00964 grains of soda = 0-386 per cent. 
e. The precipitate formed by carbonate of ammonia (c) was 
dissolved in muriatic acid, and the barytes precipitated by sul- 
phuric acid. The filtered liquor was then evaporated, again 
dissolved in water, mixed with caustic ammonia, and quickly fil- 
tered. The filtered liquor, when evaporated, deposited alumi- 
na, which, after ignition, weighed 0-038 grains = 1.52 per cent. 
Oxalate of ammonia produced in this liquor a very slight preci- 
pitate, which could not be weighed. When boiled with carbo- 
nate of potash, no precipitate fell down. 
./■' T he precipitate thrown down by caustic ammonia (c) was 
dissolved in muriatic acid, and boiled with an excess of caustic 
potash. The alkaline solution was supersaturated by muriatic 
acid, and the alumina then precipitated by carbonate of ammo- 
nia. It weighed, after ignition, 0899 grains, = 23*960 percent. 
g\ The residue (in/*) left undissolved by potash, was dis- 
solved in muriatic acid, boiled with nitric acid, and the iron 
thrown down by succinate of ammonia. The oxide of iron 
weighed 0-1378 grains = 5-212 per cent. 
h. The iron having been separated, the liquor was boiled 
with subcarbonate of potash, by which magnesia was precipi- 
tated, containing a quantity of oxide of manganese. It weighed, 
after ignition, 0.094 grains = 3-760 per cent. 
The pinite of St Pardoux is therefore composed of 
Silica, - 
( 
55.200 
0-764 
(ft) 
(d) 
) 
/ 
55-964 
Alumina, - 
23-960 
) 
<With Traces of Lime), 
1-520 
> 
) 
25-480 
Potash, - 
- 
- 
7-894 
(d) 
Soda, - - 
- 
0-386 
id) 
Oxide of Iron, - 
5-512 
<g) 
Magnesia, with Oxide of Manganese. 
> 
- 
- 
3-760 
(ft) 
Water, Avith an Animal Matter, 
- 
- 
1-410 
(a) 
100-406 
Search for Fluoric Acid . — As all micas which occur in gra- 
nite, contain a quantity of fluoric acid, I thought it necessary to 
inquire whether pinite contains this acid or not. This inquiry 
was made upon a quantity weighing 1-045 grains, according to 
