321 
on the Newry pitch-stone, &c. 
the blow-pipe, it left no black mark on the metal : it contained 
therefore no lithia. 
I proceed now to my final analysis, premising that, although 
the last, I think it may be pretty well relied upon. I had made 
a separate one for each ingredient, giving my whole attention 
to that which I had selected, without embarrassing myself 
much with the others. 
In this final analysis I adopted a different process, consider- 
ing it more convenient. My compact pitch-stone being ex- 
hausted, I was obliged to resort to the next most compact, 
and which I call the slaty compact. 
One hundred grains, mixed with 200 of caustic soda in a 
silver crucible, were exposed to a red heat. When cool, the 
contents of the crucible were softened with water and dis- 
solved in muriatic acid. A jelly was formed, by evaporating 
the solution slowly on a sand bath. When nearly dry, it 
was diffused in water and filtered. The silica caught on the 
filter, and exposed to a red heat, weighed 70,8 grains. ( a ) 
The filtered liquor (a) was evaporated to dryness, and the 
mass re-dissolved ; there remained a powder, which dried at 
a red heat, weighed 0,75, and was silica. ( b ) 
The liquor (b) from which the 0,75 of silica had been 
separated, was precipitated by ammonia and filtered ; alumina 
and iron remained on the filter ; the lime went through in 
solution (c). 
The iron and alumina were washed completely off' the 
filter into a silver evaporating dish before they were dry, by 
projecting against it water, impelled by the breath through a 
dropping glass ; a mode of removing substances from filters 
always effectual, and far preferable to drying and collecting 
MDCCCXXII. T t 
