33 1 
on the Newry pitch-stone, &c. 
Meissen pitch-stone, will it be presumption to suspect that 
Klaproth made a similar mistake • and that the substance, 
which he does not appear to have examined, and which he 
acknowledges he did not weigh, was, in reality, bitumen ? 
This cannot affect the character of this admirable analyst, 
since there was nothing in the appearance or external cha- 
racters of the Saxon mineral which could awaken a doubt on 
that subject ; whereas, the peculiar properties of the Newry 
pitch-stone, naturally, and early, arrested my attention, and 
would equally have engaged his, had it been submitted to 
him. 
Klaproth’s assertion, however, that his pitch-stone con- 
tained manganese, induced me to institute many experiments 
to obtain the same substance from mine, and in the course of 
them I had occasion to try the different methods of separating 
manganese from iron, recommended by Hatchett and 
Herschel. 
I mixed perfectly pure oxides of each metal in ascertained 
proportions, and dissolved them together in muriatic acid, and 
I found they could be perfectly separated by both methods. 
I had, at first, some doubts as to Herschel’s, but found that 
my failure had arisen from neglecting to stir the liquor during 
the precipitation of the iron. In general, I think, the sepa- 
ration is more easy by Hatchett's mode, but, under some 
circumstances, Herschel’s will be found preferable. 
There is one method of obtaining, in an analysis of a stone, 
the iron combined with the silica alone, and as muriatic acid 
easily separates them, it may sometimes be found useful. The 
heat which decomposes muriate of iron leaving an insoluble 
oxide, does not decompose the earthy muriates ; therefore. 
