10 On the Distribution of Manganese. 
exuding from some rock or stratum containing manganese In a 
minor degree of oxydation, and acquiring the higher degree by 
the absorption of oxygen and at the same time the cementing 
quality.” Dr. Davy also infers that manganese exists in the Vie 
cinity of these incrustations in large quantities, and advises 
special inquiry in search of it. 
lowing to be a full and satisfactory account of the origin of this 
phenomenon. . 
The manganese exists in almost all the igneous and metamor- — 
phic rocks of New England, and I may say in other parts of the 
world, generally as a double carbonate of lime and manganese. 
When the waters of the springs, brooks and rivers flowing ovet 
these rocks, become charged with soluble organic matter, inthe © 
meadows, the carbonates of lime and manganese enter into selu- 
tion. At such times manganese may generally be detected in these 
waters, as has been done by Drs. ©. T. Jackson 
and others. When the water holding the manganese in solution 
becomes broken and thrown up in the passage of falls or rapids, 
consequently exposing it to the influence of the atmosphere, es : 
nese luble — 
completely blackened or discolored, while in other places no such © 
depositions exist. Beautiful examples of this phenomenon may — 
be seen at some points on the Merrimac river, and indeed in 7 
and 
almost every rivulet in New England. 
I have also noticed similar depositions between the divisional 
strata planes of sandstones in the valley of the Connecticut, thus — | 
seaneag that apparently the same agencies were at work during 
fa 
he deposition of these rocks as at the present day. we 
OS Bee Re ee 
