PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 469 



manufacturers of Great Britain and the United States, use it for 

 the purpose of preserving their iron ware from the corroding 

 power of oxygen. Pipe layers also use it to prevent the rapid 

 oxygenation of iron. Bitumen is found in the following geologi- 

 cal positions, viz : 



1. In the black slates of the Taconic system, changed into an- 

 thracite. 



2. In the calciferous sandstone as an anthracite. 



3. In the Black river limestone at Montreal, in cavities of the 

 rocks. . 



4. In the Hudson river group of rocks, as bituminous shale. 



5. In the Niagara limestone at Chicago oozing from the rock, 

 giving the white limestone the appearance of having been used 

 in the walls of Babylon. 



6. In the Marcellus shales of Onondaga county, where it is 

 mistaken for coal. 



7. In all the groups of rock that extend upwards to the sub- 

 carboniferous. 



8. In the subconiferous, as petroleum, as Seneca oil in New 

 York, and Venango county, Pennsylvania, two hundred gallons a 

 day. 



9. In the same form in the coal measures at Kanawha, Vir- 

 ginia, and other streams in Ohio and Pennsylvania, also as bitu- 

 minous coal and slate. 



10. In the red sandstone of Virginia, and North Carolina as 

 coal. In the latter State, as bituminous blackband oil. 



11. In the cretaceous strata of Long Island, New Jersey,,, New 

 Mexico, and Utah, as coai or lignite. 



12. In the Tertiary, as lignite in California, and as a dyke, 

 jutting into the sea, encased in Tertiary rocks. 



13. In volcanic rocks — from both extinct and living volcanoes. 



14. In the sands of Trinidad, as a bubbling lake in the mid- 

 dle, but hardened on the edges. 



Mr. Seeley presented a specimen of paper of Japanese manu- 

 facture, for the inspection of the members present. 



DENTISTRY. 



Robert L. Pell being called upon, remarked as follows : 

 Teeth are the hardest structures belonging to humanity ; with- 

 out them man would be unable to articulate a single syllable, 

 and expression to the face would be lost ; they are formed by 



