1822.] Philosophical Transactions for 1822, Part IT. 461 
into thin slaty fragments : 100 grains of the same in fine powder 
were exposed to a white heat in a platina crucible, and were 
converted into a very paie leek-green glass, losing 10 per cent. : 
220 grs. coarsely powdered being ignited in a coated glass retort 
-yielded 16 grs. or 7°2727 per cent. of a colourless fluid, having 
a slightly bituminous smell. ‘ The stone finely powdered and 
projected on melted nitre scintillated a little.” 
Mr. Kniox next proceeded to ascertain the constituents of the 
mineral, following the method of Klaproth in his analysis of the 
pitchstone from “Meissen, which analysis he details. In thus 
examining the Newry pitchstone, he obtained neither manganese 
nor magnesia. 
The muriatic solution divested of silica evaporating with con- 
siderable rapidity,’ a black powder separated from it, which was 
insoluble in acids, and burned away at a red-heat ; it was at first 
suspected that some carbon had accidentally got into the liquor, 
but it was proved to belong to the stone by repetition of the 
experiments and by other circumstances. It was ascertained by 
the process with nitrate of barytes that the mineral contained 
soda, which was unmixed with potash or lithia. 
‘Mr. Knox then proceeds to describe his final analysis, in 
which he used the slaty-compact variety of the pitchstone, 
his specimen of the compact one having been exhausted. 
He obtained the silica in the usual method by fusion with soda, 
precipitated the alumina and iron by ammonia, and separated 
them by boiling in caustic potash ; obtained the lime by preci- 
pitating the solution freed from alumina and iron with carbonate 
of soda, and precipitated the alkaline solution of alumina by 
muriate of ammonia. 
We have now arrived at that part cf the analysis in which the 
author endeavoured to ascertain the proportion of alkali in 
the stone; and this we cannot but deem defective. Our che- 
mical readers will be surprised to learn, that rejecting the 
process with nitrate of barytes as tedious and liable to loss, 
that by boracic acid as difficult, and also the new process b 
lead, Mr. Knox, for the purpose of extracting the soda, boiled 
100 grains of the pulverized stone in dilute nitric acid, taking up 
by water the soluble part when the fluid had been driven off, and 
replacing the acid ; this process being “ repeated until the acid 
seemed to have no further effect.” By this method, 7-75 gers. of 
nitrate of soda were obtained, giving 2°857 for soda. 
We apprehend that we shall be supported by the testimony of 
all persons who are versed in analytical chemistry, in affirming 
that it is impossible to extract from a siliceous compound the 
whole of the alkali which it contains by this mode of operating. 
As to the result by muriatic acid, which the author adduces as 
confirmatory of the above, his statement of it is incorrect ; he 
obtained five grains of chloride of sodium, which, he says, 
“make of dry soda, or oxide of sodium, 1°98198, being in the 
