from St Pardoujc in Auvergne. 
leave to observe, that I have discovered a considerable quan- 
tity of ammonia in the natrolite of Hohentwiel, and in the por- 
phyry-slate itself, in which the natrolite is found in veins. ( Gil- 
bert's Annalen , 1820, No. iv. p. 861). 
Analysis. — a. 1 49 grains of pinite in coarse pieces, were re- 
duced by ignition to 1-459 grains ; 100 parts, therefore, would 
experience a loss of i - 410. 
b. 2.5 grains of pinite, after having been reduced to an im- 
palpable powder, were mixed with 1 2.5 grains of carbonate of 
barytes, and ignited ; the mass cohered loosely, and assumed a 
green colour. When dissolved in muriatic acid, chlorine was 
evolved. Silica, separated in the ordinary way, weighed, after 
ignition, 1-88 grains = 55*200 per cent. 
c. The liquor was now precipitated by carbonate of ammo- 
nia ; the precipitate which fell down was separated by the filter, 
and well washed. The solution was then evaporated to dryness, 
and the dry mass fused. Alcohol and a little muriatic acid were 
poured upon the fused mass, and the alcohol set on fire ; but 
there appeared nothing of a green or purple colour, a circum- 
stance by which the absence of boracic acid and lithium is 
proved. 
d. The muriate of alkali converted into a neutral sulphate, 
weighed 0’887 grains ; when dissolved in water, 0-0191 grains. 
Silica = 0-764 per cent, were left undissolved. The sulphate was 
now converted into a carbonate by means of acetate of lead, which 
was dissolved in water, leaving a small residue of oxide of manga- 
nese. The solution was saturated by muriatic acid, and evapo- 
rated, in order to drive off the excess of acid. The muriatic 
salt was dissolved in a little water, and mixed with a concentrat- 
ed solution of muriate of platina. The precipitate was washed 
with a small quantity of water. The solution which passed 
through the filter was mixed with some sulphuric acid, evapo- 
rated, and exposed to an intense heat. The sulphate was sepa- 
rated from the metallic platina by means of water, and put aside 
for crystallization. There were formed crystals of sulphate of 
soda, which effloresced perfectly on exposure to the atmosphere, 
and weighed in this state, 0-022 grains. This quantity being 
deduced from the whole quantity of the salt (0-887 grains), 
there remain for the sulphate of potash 0 865 grains. 2.5 grains 
