i $6 Mr. Howard's Experiments and Observations 
grains, may be estimated between 1 and 2 grains. Some glo- 
bular bodies were extracted, but too few to analyze. 
Since the pyrites could not be separated, I collected 150 
grains of the stone, freed from iron by the magnet, and as 
exempt as possible from globular bodies. These 150 grains, I 
first digested with muriatic acid, that the pyrites might be 
decomposed, and every thing taken up which could be dissolved 
by that menstruum. A very decided disengagement of sul- 
phureted hydrogen gas was occasioned. When the acid could 
produce no further action, I collected the undissolved matter on 
a filtre, and boiled it with the most concentrate nitric acid, in 
hopes of being able to convert the sulphur, previously liberated, 
into sulphuric acid ; but my endeavours were fruitless ; for, 
upon the addition of nitrate of barytes to the nitric solution, 
rendered previously transparent, a very insignificant quantity 
of sulphate of barytes was obtained. The surplus of barytic 
nitrate was removed by sulphate of potash. I next completely 
edulcorated the mass which remained insoluble, after the action 
of. the muriatic and nitric acids; and, adding the water of edul- 
coration to the muriatic and nitric liquors, evaporated the whole 
for silica. I then submitted the mass, undissolved by the acids 
and the water, to the treatment with potash, muriatic acid, and 
evaporation, which was, in the first instance, applied to the 
stone from Benares. The first precipitation was, as in that ana- 
lysis, also effected with carbonate of potash ; but, instead of 
endeavouring immediately to extract alumina, I ignited the 
precipitate, that the alumina or silica remaining might be ren- 
dered insoluble. After the ignition, I separated the oxide of iron 
with very concentrate muriatic acid; and the earths, which 
were left perfectly white, I heated with potash, until they were 
