Analysis of a Manganesian Garnet. 157 
change of colour clearly proved, that the iron and manga- 
nese existed in a minimum state of oxidation, therefore, 
the 0.486 grammes of peroxide of iron must be reduced to 
the state of protoxide, and are equivalent to 0.448 grammes 
of protoxide of Iron on 3 grammes, or 14.93 per 100. 
. The filtered liquor, (D) was boiled with an excess of 
sub-carbonate of soda, the carbonate of manganese thus pre- 
cipitated, was washed and strongly. calcined, the tritoxide 
of manganese weighed 1.007 grammes, and on examination 
was found to contain neither alumina nor iron: the 1.007 
gr. of tritoxide are equivalent to 0 929 grammes of protox- 
ide of manganese on 3 grammes, or 30.96 per 100. 
F. The liquor (C), after filtration was successively tested 
with oxalate of potash, and with caustic potash, and thus 
proved to contain neither lime nor magnesia. 
According to the preceding experiments, the constituents 
of this Garnet are 
Per qer pra eee 
A. Water, -  - 00.66 containing oxygen — 
B. Silica, - - - 35.83 - mle eo 3 
C. Alumina, - . 18.06 - - 08.43 
D. Protoxide of Iron, - 14.93 - - 03.39 
E. Do, of Manganese 30.96 - - 06.79 
100.44 18.61 
And its mineralogical formula will be fS+2mgS+2AS. 
Boric acid in Tourmalines. | 
To detect the Boric acid in the green Tourmaline, from 
Chesterfield, Massachusetts, a portion of the mineral was 
pulverized, and calcined at a red heat, with three parts of 
caustic potash ; the mixture after calcination, was treated 
with muriatic acid and evaporated to a dry gelatinous mass, 
which was afterwards digested in alcohol; the alcoholic so- 
lution, when ignited, burnt with a beautiful green flame, a 
proof of the presence of Boric acid ; the same acid was al-. 
so found, by a similar treatment, in the Rubellite and Indi- 
colite from Massachusetts, and in the black Tourmalines 
pn Haddam, Connecticut, and Chester creek, Delaware 
ae 
0. 
