246 The Aiiten'c<ni Geoloijisf. April, 1895 
In support of this hypothesis a seri(*s of analyses of the 
rocks of the state was undertaken by the writer to determine 
the presence and amount of the metals in question. In the 
report referred to the results of these analyses are given in 
full, as well as the method pursued. Here it will 1)e suflicient 
to give an outline of the results. 
ytitiiJIifn-ixis Ciittnils of Missouri iiorl.s. 
Luad piT I flit, /inc per cent. 
Alien KAN llocKs. 
lv;iii,i:v of S aiialysi's of -1 spccimi'iis O.OOl!)? to O.OlHiSO (i.Odi:!!) lo 0.01 TCO 
SiniirAX Macxksian I.i.mksio.nks. 
Uaiiuc of ri aiialysi'Sot'G specimens Trace to ().<)(»!.")() Trace lo O.Ol.'jItS 
LowEK Cahbomfkkous Limestones. 
Ilaiif^c ol' 1.") analyses of 7 specimens Trace to ().0034() Trace lo (i.o02.")G- 
These analyses were made with great care and after much 
experimenting. While there are not a sufficient number of 
determinations to base many generalizations upon, they cer- 
tainl}" afford results of a very significant nature. Copper, 
manganese, and barium sulphate were also determined, al- 
though the results of these determinations are not given here. 
The presence of larger amounts of these metals in the im- 
pervious crystalline rocks certainly points to the conclusion 
that they existed there originally and were not introduced 
subsequentl}'^ from more recent sources. The average eon- 
tents of the limestones are thus 0.001009 (/f lead and 0.00239% 
zinc, which is equivalent to 0.00198 ft)S. galena and 0.00603 ft)S.. 
blende to the cubic foot of rock. This would give — 
'1'1"!> tons ualena per s(piare mile, 1 foot tliicl<. or 
i:{.!)00 tonsg-alena per s(piare mile, .')00 feet thick, and 
S:{.(i tons blende per s([iiare mile, 1 foot thick, or 
4]..'i00 tons blende per scpiare mile, .")0() feet thick. 
Thus we find, according to our hypothesis, which does not 
limit the action of lateral secretion to the immediate wall 
rocks of the deposit, that the metalliferous contents of the 
rocks are ample to suppl}'^ the ore deposits. 
In support of this hypothesis we have evidence of great and 
prolonged erosion during ditt'erent geological periods, as has 
been referred to before. This has occurred in Wisconsin as 
well and has been noticed by all the writers on the geology of 
that state. The hypothesis also accounts for the dolomization 
of the Lower Carboniferous limestones, the waters draining, 
the Lower Silurian areas carr^'ing in solution suHicient mag- 
