1 82 TRANS. ST. LOUIS ACAD. SCIENCE. 



same. — This theory was held by Stahl, Zimmerman, Von Charpentier, 

 and Von Trebra. 



2. Theory of Lateral Secretion : the lodes, fissures, or veins, have been 



filled from the neighboring rock. — Delius, Gerhard, Lasius. 



3. Theory of Descension : the veins or fissures have been filled by material 



furnished from some source above. — Baumer, Werner. 



4. Theory of Ascension : this theory claims that the veins were filled by 



material brought from below, and may have been introduced in the 

 following manner : 



a. By Infiltration : the material was deposited from an aqueous so- 



lution, as mineral water. — Lasius. 



b. Bv Sublimation : O.. the material was introduced into the fissures 



bv ascending steam. — Lehmand and perhaps Becher. 

 Bv Sublimation : p. the fissures were filled by sublimation from 

 matter in a gaseous condition. 



c. By Injection : an igneous force has injected the matter while in a 



fluid condition into the fissures, where it afterwards solidified. 



Cotta says that neither the theory of contemporaneous formation 

 nor that of descension has had any upholder since Werner, thus 

 leaving only a choice between the theories of Lateral-secretion 

 and Ascension. 



Now if by the former a literal interpretation is rendered, and it 

 is understood in the sense that the ore-deposits resulted from the 

 immediate contact rock, through which some solvent passed dis- 

 solving out the ingredients and afterwards depositing them in the 

 veins or fissures, then this theory would not account for the ore- 

 deposits which have come under my observation ; but if we may 

 interpret the term lateral not as applied literally, and look upon 

 the contact rocks not as the source of the material furnished, but 

 merely as conductors through which the solvents passed holding 

 the material in solution, then the Lateral-secretion theory, in my 

 opinion, accounts for all the vein ore-deposits which I have care- 

 fully examined. 



The ore-deposits of this State which occur in the Lower 

 Silurian formation may have resulted, especially the bedded 

 ore, by a direct precipitation from a solution, or by the Ascen- 

 sion theory as defined by Cotta, as, for example, the veins of 

 specular-ore in the 3d Sandstone formation in Crawford Coun- 

 ty ; for, though having seen these formations, I have not been 

 able to correlate the few facts gathered, and can offer no the- 

 ory for their origin. But the Ascension theory will certainly 

 not account for many of the ore-deposits found in the por- 

 phyries of the Palaeozoic formation ; for neither by sublimation 



