190 
the alkaline ley, was dissolved in the same acid. The so- 
lution was assayed by a drop of Muriatic Acid, which causéd 
the precipitation of a white matter; but it was redissolved - 
on shaking the fluid,—a circumstance which proves the 
absence of Silver. The Lead was separated by liquid Sul- 
phate of Soda, and added together, the Oxide of which, 
according to calculation, amounted to 17°179. Ammonia 
afterwards precipitated a greenish white matter, a portion 
of which a further addition of Ammonia redissolved. The 
former proved to be Oxide of Iron = 0°17, and the latter 
Oxide of Copper which amounted to about 0°1. The Silica 
which remained undissolved by Nitric Acid, and which 
was separated from the Potash, amounted to 0°815. The 
Alumina was in too small a quantity to be estimated. 
This, and the Silica, and probably the minute portion of 
Copper also, proceeded, I believe, from the gangue of this 
fossil. There is a deficiency of 2°836, which is to be at- 
tributed in part, I think, to a retent of water of crystalli- 
zation, in addition to the loss which is unavoidable in such 
experiments, more especially when smal] quantities are ope- 
rated upon, and a repetition of experiments is precluded 
from the scarcity of the mineral.” 
ead’: Oo roxisees. hea 
Arsenic Acid . . 4°62 
Water ¢5 -  Suadotek sis Olas 
SICA“. Se es ee. OSES 
from 8s. DUR et One 
Oxide of Copper . Ol 
Alumina andloss . 2°836 
26°200 
Since the above was written, Mr. Gregor, having been 
enabled to extend his experiments, has informed me that he 
suspects the presence-of the Muriatic as wel] as the Arsenic 
Acid in this substance, and that he intends presenting the 
Royal Society with an account of the results of his more 
extended experiments. 
