J. Hall on Carboniferous Limestones of Mississippi Valley. 187 
me fragments of the original cake, with prismatic crystals 
upon them, were treated with bi-sulphuret of carbon. This rap- 
€ yellow modification dissolved, as observed by Deville and 
agnus. 
The portion insoluble in bi-sulphuret of carbon was of a red- 
brown color, and amorphous; it retained in some cases the pris- 
to the bottom of the vessel, on shaking, as a 
powder. A little of this insoluble red sulphur was heated in 
Platinum foil, and burned without any residue. 
A fragment of the original cake, heated in a test tube up to 
the boiling point of sulphur, sublimed, and appeared after subli- 
Arr, XXTI.— Observations upon the Carboniferous Limestones of 
the Mississippi Valley ;* by JAMES Hauu.  [Abstract.] 
b 
limestone ” as it is usually termed, of the Mississippi valley. The 
were 
Certain supposed characteristic fossils, such as the Archimedes, 
the Pentremites, etc., which, though reliable as individual species 
In their geological range, are not, as genera, characteristic of the 
subdivisions, The subdivisions proposed in the report of Dr 
* From the Proceedings o! iean Association for the Advancement of 
Sine Tan nc eee ret a ae hap of ope 
