Dr Gmelin on a Black Mineral from Candy in Ceylon. 88 5 
Infusible without addition before the blowpipe. Even when 
reduced to the finest powder, and mixed with spar, it cannot 
be melted by the most intense heat : it only becomes glassy 
on the edges. Phosphoric salt takes it up readily, and in large 
quantity, and melts with it into a translucid greenish glass. By 
means of nitre, traces of manganese are detected. Borax, in 
the same manner, melts with it into a greenish glass. When 
mixed with a little soda, the powder swells up to a yellowish- 
grey porous mass ; but it is impossible to melt it by an addi- 
tional quantity of soda. 
I experienced great difficulty in decomposing it, and my first 
attempt, by melting it with five times its weight of carbonate of 
potash, was not perfectly successful. A great deal of the melted 
mass was left undissolved by muriatic acid. Eight hours were 
spent in reducing 1.2 grammes of the mineral to an impalpable 
powder in an agate mortar. 
(1.) 1.175 grammes of the dried powder were heated strongly 
with seven times its weight of carbonate of soda in a platina cru- 
cible. The brown melted mass was perfectly dissolved by muriatic 
acid. The muriatic solution was evaporated to dryness, and the 
dry mass again dissolved in boiling water, mixed with some mu- 
riatic acid. There remained silica, which, after having been 
heated, weighed 0.03706 gr. =3.154 per cent, of silica. 
(2.) The liquid solution was then mixed with caustic ammonia, 
and the precipitate was thrown upon a filter, and well washed 
with boiling water. 
(3.) The liquid which had passed the filter gave no precipi- 
tate with oxalate of ammonia, but was precipitated by carbonate 
of potash, when boiled with it. The precipitate in (2.) was 
boiled with an excess of caustic potash, which dissolved alumina. 
The residuum was thrown upon a filter, and well washed. The 
alkaline solution, after having been supersaturated by muriatic 
acid, was precipitated by carbonate of ammonia. The alumina, 
when thoroughly washed, was found to weigh 0.6721 gr. = 
57.200 per cent. No trace of glucine could be discovered. 
(4.) The brown mass (3.) which was left undissolved by 
caustic potash, was dissolved in muriatic acid, and the solution 
boiled with some nitric acid. The oxide of iron was then pre- 
b b 
VOL. IX. NO. 18. OCT. 1823. 
