CLARKE AND 
STE1GEK. 
JONSTITUTION OF PECTOLITE. 
15 
utes with a solution of sodium carbonate containing 250 grams to the 
liter. In the extract so obtained the silica was determined; and three 
experiments gave the following percentages: 
8.96 
8.67 
8.42 
Mean, 8.68 
One-sixth of the total silica is 8.89 per cent; and the experiments, 
therefore, justify the original expectation. The belief that pectolite is 
a metasilicate is effectively confirmed. 
Upon the unignited pectolite the sodium carbonate solution has a 
slow decomposing action, both silica and bases being withdrawn. In 
two experiments fifteen minutes of boiling extracted 2.07 and 2.55 per 
cent of silica, and by a treatment lasting four days 4.80 per cent was 
taken out. With water alone similar results were obtained; the action 
being so rapid, although relatively slight, that pectolite, moistened, gives 
an immediate and deep coloration with phenol phthalein. By boiling the 
powdered pectolite with distilled water alone 1.65 percent of silica was 
brought into solution, and the ignited mineral, similarly treated for 
fifteen minutes, gave 1.78 per cent. The extraction in these cases is 
really an extraction of alkaline silicate, as the two following experi- 
ments prove. In A the unignited pectolite was boiled for fourteen 
hours with distilled water: and in B the mineral after ignition was 
subjected to like treatment for four hours. The dissolved matter in 
each case was determined, with the subjoined results: 
A. B. 
Si0 2 
2.98 
.30 
.81 
3.03 
.10 
1.50 
CaO 
Na ( > 
4.09 
4.63 
In A, no simple ratio appears; but in B the extracted silicate approxi- 
mates very nearly to the salt Na 2 Si 2 5 . In each instance the ratios 
vary widely from tliose of the original mineral, showing that actual 
decomposition and not a solution of the pectolite as such has occurred. 
In the experiments upon pectolite the heating with dry ammonium 
chloride was omitted, for the data are already given in the original 
paper by Schneider and Clarke. In their experiments the mineral was 
thrice heated with ten times its weight of the reagent to above 350°, 
and then leached out with water. In the solution 20.50 per cent of lime 
and 0.95 of soda were found, with part of the manganese; showing that 
a very considerable decomposition had taken place. Possibly, by 
