AMERICAN INSTITUTE. 481 



PoLYTEcnNic Association of the American Institute, ) 



October 27th, 1859. } 



S. D. Tillman, Esq., in the chaii*. Mr. Haskell, Secretary, pro tern. 



Miscellaneous business having been disposed of, a very eloquent paper 

 on " the Metamorphoses of Iron, or its ores in different geological epochs,'* 

 was read by Dr. R. P. Stevens, 



Setting out with the declaration that modern geology teaches the law of 

 "the stability or instability," he illustrated his position by reference to 

 the continual changes taking place in bodies, leaving it doubtful whether 

 any "molecule" of matter had at present the precise "form," " association," 

 and locality it had originally. 



His position was mostly illustrated by reference to the changes produced 

 by " pseudomorphic," and " metamorphic " action, in the "bosom of the 

 ocean " ; by convulsions of the earth combined with " heat " and " pressure," 

 changing soft deposits into shales and slates ; by igneous action ; and finally 

 by "streams and river courses." 



In continuation, the paper proceeded to show, after stating that the earth 

 has its chemical history, that " iron serves to illustrate its grand epochs." 



Pointing out the two methods of proceeding in geology, namely, begin- 

 ning with " primitive " formations, and proceeding forwards and upwards 

 to those of the present day ; or commencing with the recent to travel back- 

 wards until " we reach the confines of our actual knowledge, and the misty 

 realms of theory and conjecture," he selects the latter. 



He then traces iron through the forms of bog ore, confined to the "post 

 Adamic history of the earth"; brown hjematite which marks the "drift 

 epoch and deposits;" the carbonates of iron, in their varieties of 



1. The "black band;" 



2. The kidney ore, or argillao-carbonate of iron ; 



3. The silico-carbonate, or flint ore of Pennsylvania ; 



4. The limestone ore ; 



5. The septaria, a carbonate with alumina; 



6. A bed of black band, about 40 feet above the lower bed of coal ; 



7. Another bed of the same immediately beneath, and 



8. Another bed of carbonate, 40 feet beneath the coal ; 

 marking the " second great chemical epoch." 



' Passing by the " Devonian, "^he next proceeds to speak of the lenticular, 

 or oolitic ore of Madison county, N. Y., as marking the " Silurian " epoch 

 of geologists. 



He finally passes to the primitive epoch, marked by the " magnetic, the 

 specular, and peroxide" of iron. In speaking of them he "rejects the 

 Plutonic theory of their formation," and " accepts heat, only as a modifying 

 agency." 



From this discussion he draws the " practicallesson " that each geological 

 epoch has, as well as "its remains of organic life, certain mineralogical 

 features by which.it may be identified." 



Mr. Wiard, the inventor of the steam ice-boat, was next called out, and 

 [Am. Inst.] 31 



